UnB/IG - DISSERTAÇÕES E TESES DE OUTROS CURSOS
DE PÓS-GRADUAÇÃO NO BRASIL

cpggeo/Curso de Pós-Graduação em Geociências - UFRGS
PhD T H E S E S - (this page)
TESES DE DOUTORADO -(esta página)

[MSc Theses (Stratigraphy)]
[MSc Theses(Marine Geology)]
[MSc Theses(Geochemistry)]
[MSc Theses(Paleontology)]

Área de concentração (Thesis subject):
Estratigrafia (Stratigraphy)
Geologia Marinha (Marine Geology)
Geoquímica (Geochemistry)
Paleontologia (Paleontology)

OBSERVAÇÕES SOBRE O GRUPO TUBARÃO NO RIO GRANDE DO SUL, COM ESPECIAL DESTAQUE À ESTRATIGRAFIA DA FORMAÇÃO ITARARÉ

OBSERVATIONS ON THE TUBARÃO GROUP IN RIO GRANDE DO SUL, WITH SPECIAL EMPHASIS ON THE STRATIGRAPHY OF THE ITARATÉ FORMATION

Zuleika Carreta Corrêa da Silva (1977)

Adviser: Paulo Miranda de Figueiredo Fº

Associated Adviser: Renato Rodolfo Andreis

Abstract

This thesis includes a discussion on the stratigraphy of the Tubarão Group in Rio Grande do Sul State, on the basis of a detailed study of two main areas of its occurrence: Mariana Pimentel­Cerro do Roque and Coxilha do Tabuleiro Quadrangle.

In those two areas the group is subdivided into two formations, Itararé and Rio Bonito. The former includes two facies in Rio Grande do Sul: Mariana Pimentel (new name) and Budó (redefined). These units are contemporaneous and essentially clastic. The Rio Bonito Formation is the only representative of the Guatá Subgroup occurring in the studied areas.

A revision of the palaeontological content of both facies indicates that the Mariana Pimentel facies contains the genera Paracalamites, Glossopteris, Gangamopteris, Buriadia, Gink-gophyllum, Samaropsis, Cornucarpus, Noeggerathiopsis and cfr. Nephrosis. Fossils of the Budó facies are mono and triaxonic spicules, scolecodonts, fish scales and teeth, Orbiculoidea, Langella, Aviculopecten, Paracalamites, Glossopteris, Gangamopteris, Noeggerathiopsis, Botryochiopsis and Chiropteris.

The paleaofloristic assemblages point out to an Early Permian (Sakmarian) age for the Itararé Formation; the age of the Rio Bonito Formation is suggested to be younger, perhaps Artinskian.

The depositional environment of the Budó facies is believed to be shallow marine, whereas it is proposed here a lacustrine environment for the Mariana Pimentel facies. The Rio Bonito Formation includes mainly fluviatile deposits.

DISTRIBUIÇÃO DOS SEDIMENTOS CENOZÓICOS NA REGIÃO METROPOLITANA DE CURITIBA E SUA RELAÇÃO COM A ESTRUTURA GEOLÓGICA E MORFOLÓGICA REGIONAL

DISTRIBUTION OF CENOZOIC SEDIMENTS IN THE METROPOLITAN REGION OF CURITIBA AND THEIR RELATION TO THE REGIONAL GEOLOGIC AND MORPHOLOGIC STRUCTURE

Rosemari Dora Becker (1982)

Adviser: Milton Luiz Laquintinie Formoso

Associated Adviser: João José Bigarella

Abstract

The present contribution is a tentative to integrate the geologic, geomorphologic and sedimentologic features related to the Cenozoic formations from the Curitiba Metropolitan Region. Office, laboratory and field studies allowed new approaches and interpretations concerning the relationship between the geologic structures and the erosive and sedimentary problems.

The morphology of the terrain comprises erosive and sedimentary levels. These features were surveyed concerning the origin of the forms and the role they played in the development of the stratigraphic sequence.

The sedimentological analysis characterized the sedimentary types. The integration of the available data permitted the establishment of correlations between the geologic and geomorphologic features.

The morphology changed accord-ing to the geologic structures and the drainage system pattern. There were recognized in the oriental part of the State of Paraná three main erosion surfaces referred as the pediplanes Pd3, Pd2 and Pd1. Inset in the latter there are two pediment levels: P2 and P1. Below the P1 there are gravel terraces and flood plain terraces. All these levels are polygenetic in nature and related to climatic changes.

The alternation of two main groups of climatic conditions was represented by semiaridity and humidity episodes. These episodes were responsible for the development of the succession of topographic forms and for the deposition of several sedimentary sequences represented by the Guabirotuba, Tinguis and Boqueirão Formations, as well as by the depositon of the alluvial flat deposits and the colluvium­alluvium ramps.

The climatic alternations caused changes in the hydrodynamic and morphodynamic processes, which originated respectively the lateral degradation and the vertical dissection of the terrain.

The source area for the Cenozoic sediments was located around the Curitiba Basin and comprised terrains of different lithologies, which are represented by the crystalline basement, by the Setuva and Açungui groups and by the Camarinha and Guaratubinha Formations.

The Cenozoic sequences are made up of several sedimentary units separated by erosive unconformities visualized through the stratigraphic and geomorphologic approaches. The former paleoclimates from the time of deposition were interpreted from the mineralogic analysis and from the examination of the sedimentary structures and textures.

Pediplanes and pediments were originated from processes causing the lateral degradation of the terrain during semiarid times. At the same time, sedimentary sequences were deposited in the basins of a dissected landscape. These climatic episodes were of a cyclic nature.

In the Curitiba Basin more than a paleoclimatic event happened being responsible for the sedimentary succession. The Guabirotuba Formation was deposited in a desertic environment during the time of the development of the pediplane Pd2, probablyduring the Lower Pliocene. The temperature at this time possibly was somewhat cooler than the present one. The Tinguis Formation was separated from the upper part of the Guabirotuba Fm., and correlated with the development of the pediplane Pd1 and the pediments P2 and P1. The sediments of the Tinguis Fm. represent the reworking of the Guabirotuba sediments. The Boqueirão Fm. was deposited during the Upper Pleistocene in a braided stream environment. Both the Tinguis and Boqueirão Formations were deposited under semiarid conditions.

In Curitiba Basin the mean diameter of the sediments depends of the energy of the environment. Most of the samples of the Guabirotuba and Tinguis Formations, and most of those from the alluvial flat deposits are very poorly sorted, showing that the transport agent was unable to sort the sediment. The Boqueirão Fm. sediments are better sorted, due to transport by a braided stream system.

FÁCIES, AMBIENTES E CARVÕES NA FORMAÇÃO RIO BONITO NO SUL DO ESTADO DO PARANÁ: UMA ANÁLISE ESTRATIGRÁFICA

FACIES, ENVIRONMENTS AND COALS OF THE RIO BONITO FORMATION IN SOUTHERN PARANÁ STATE: A STRATIGRAPHICAL ANALYSIS

José Henrique Popp (1982)

Adviser: Zuleika Carreta Corrêa da Silva

Associated Adviser: Paulo César Soares

Abstract

The results obtained through stratigraphic analysis on a regional scale, in the Rio Bonito Formation (Lower Permian of the Paraná Basin) are presented herein. The survey was performed over an area of about 3,000 km², in the southern region of the State of Paraná.

The main purpose of the research was to analyze the faciologic and depositional parameters of the coal­bearing deposit and the possibility of its economic exploitation.

About 90 well logs and several field sections were studied.

The interpretation of the sedimentary environment was made through the formats (curve shapes) of gamma rays and resistivity logs related to the physical properties of the facies, supplemented by lithologic control from outcrop description and samples from strategically located wells.

The lower member of Rio Bonito Formation (Triunfo Member) was originated in a deltaic province prograding over prodeltaic siltstones of an epicontinental shallow sea.

The upper part of this member is of a retrogradacional nature, being covered by transgressive marine deposits of the Paraguaçu Member.

In the interdistributary bay of the Triunfo Member deltaic plains several peat swamps and marches were formed.

Owing to high clastic influx and low subsidence rate, the peat accumulation was thin, being preserved as coal beds thinner then 50cm with a high ash content.

CARACTERIZAÇÃO DA MATÉRIA ORGÂNICA DISPERSA NOS SEDIMENTITOS DA FORMAÇÃO IRATI, PERMIANO SUPERIOR DA BACIA DO PARANÁ

CHARACTERIZATION OF THE DISPERSED ORGANIC MATTER WITHIN THE SEDIMENTS OF THE IRATI FORMATION, UPPER PERMIAN OF PARANÁ BASIN

Maria Iêda de Almeida Burjack (1984)

Adviser: Zuleika Carreta Correa da Silva

Associated Adviser: Sérgio Archangelsky

Abstract

This thesis deals with the analysis and discussion of the organic matter dispersed within the sediments of the Irati Formation (Upper Permian of Paraná Basin). The data are related to the samples collected in fourteen boreholes from the southern States of Santa Catarina and Rio Grande do Sul. The samples contain, in addition to the Irati Formation, sediments from the top of Palermo Formation and from the middle and lower parts of Serra Alta Formation.

The palynological analysis showed a rich assemblage dominated by striated pollen grains, also containing algal remains and spore grains. In addition to a generic emend and a new combination, three new species are formally proposed: Lueckisporites inflatus, Staurosaccites quadrilobatus and Staurosaccites quadrangularis. Furthermore, there is presented a correlation attempt between micro and macroflora, based on bibliographic data.

The vertical distribution of palynomorphs found in the Irati Formation, through the Permian sediments of Paraná Basin, has made possible the suggestion of a biozonation system, consisting of an assemblage­zone called Lueckisporites­Staurosaccites Assemblage­Zone subdivided into two subzones: Marsupipollenites­Weylandites Assemblage­Subzone (lower position) and Colpisaccites­Falcisporites Assemblage­subzone (upper position).

Relative datings enableb to deduce a Kazanian/Tatarian age for the assemblage­zone which includes the sediments of the Palermo Formation and the Serrinha Member. In reference to the lower assemblage­subzone, which is related to the Palermo Formation sediments and possibly to the basal part of the Irati Formation, an Upper Kazanian age is suggested; as to the upper assemblage­subzone, which incloses the sedimentar sequence between the middle part of Irati Formation and the Serrinha Member, an antiquity related to the Tatarian age can be attributed.

The organoclast analysis under transmitted light has shown the presence of different organic facies. The levels and layers of oil shales are characterized as presenting a sapropelic organic facies, related to the kerogen Type I; vitro­inertinitic organic facies, related to the kerogen Type IIIB or Type IV, are found in the other lithologies (except Lime-stones).

The organopetrographic studies, made under white and ultraviolet light, mainly because of the great abundance of alginite B, allowed the classification of the levels and layers of oil shales as lamosite. The thermal alteration index and the vitrinite reflectance point out to an immature petroleum source rock or within the diagenetic stage. This maturation stage is equivalent to lignite/sub­bi-tuminous coal, according to the coal rank classification.

All the analyzed data made evident a paleoenvironment composed of fresh or brackish water for the deposition of the analyzed lithologies. The genus Botryococcus has contributed decisively to the accumulation of the organic matter.

Finally, in the form of complementary data, the results achieved through the geochemical and fluorometrical analyses are presented.

ESTUDO DA SEQÜÊNCIA CLÁSTICA E CARBONÁTICA DA SERRA DO TONÃ MACURURÉ, ESTADO DA BAHIA

STUDY OF THE CLASTIC AND CARBONATIC SEQUENCE OF THE TONÃ RIDGE, MACURURÉ, BAHIA STATE

José Lins Rolim (1984)

Adviser: Gerardo Eugênio Bossi

Associated Adviser: Benjamin Bley de Brito Neves

Abstract

A systematic analysis of the clastic and carbonatic sequence of the Tonã Ridge (Macururé municipality - Bahia State), a part of the uppermost cover of the North Tucano Basin, was made with the purpose of solving a few stratigraphic problems of the continental Cretaceous of northeastern Brazil. Accordingly, field and laboratory investigations were made, as well as the consultation to the pertinent bibliography.

The first phase consisted of the field reconnaissance, geological mapping, survey of the gravimetric and magnetometric anomalies, sampling, elaboration of detailed stratigraphic sections and measurement of paleocurrent structures.

Conventional studies on sedimentology, petrography, geochemistryand interpretation of sedimentary structures permitted us to rationally interpret the tectono­sedimentary and paleogeographic features which determined the depositional environment as well as a new lithostratigraphical concept in reference to the Marizal Formation.

The nature of the contacts, associated with its properties or lithologic attributes, allowed to rise this unit to the category of a group, comprising two well defined lithosomes: 1) a lower detritic sequence, possibly with one or more formations; 2) a carbonatic sequence, defined as Serra do Tonã Formation, making up the last depositional Early Cretaceous record locally preserved.

TEMPESTITOS DA BACIA DO PARNAÍBA

TEMPESTITES OF THE PARNAÍBA BASIN

Jorge Carlos Della Favera (1990)

Adviser: grau obtido diretamente por defesa de tese

Abstract

Although tempestites - or storm deposits - were only recognized as such in the 1970s, they constitute one of the most frequently occurring facies in sedimentary records. This dissertation examines the tempestites of the Parnaíba Basin of Brazil from the Devonian through the Permian.

We have relied on the holistic paradigm, which presumes that the universe is a dynamic web of related events, in which none of the properties of any one part of the web are fundamental, but rather all properties are a result of the other parts of the whole; it is the overall coherence of the interrelations within the web that will determine its structure. One of the ways in which the holistic view was applied in this study was the use of the "Zoom Method". Its goal was to establish the context, or part of the holistic web, wherein the problem is located, by means of a coordinated examination of observations of different magnitudes. In this approach, relations are thus more important than objects them-selves.

An extensive review of the literature on the state of the art of tempestite models indicates that the facies is abundant in sections that formed in shallow marine or lacustrine environments on muddy shelves. A "classic" tempestite can be recognized through the identification of hummocky cross­stratification, nor-mally found in upwards - fining layers that reveal truncated wave­ripples within. One special type, denominated as "oscillatory turbidite", displays a gradation of internal structures in which the crest spacing of the undulated laminae decreases upwards as their height increases. The genesis of hummocky cross­stratification involves the simultaneous action of unidirectional and oscillatory flows, which generate bi­ or tridimensional migratory bedforms: it is impossible to confuse a hummocky structure with through cross­bedding, contrarily to what has been suggested by some authors. Although the question is still under debate, the determinant process in the formation of these combined flows seems to be the process generated by gradient currents and characterized by superimposed waves in the proximal part and geostrophic currents in the distal. Tempestites can be found at depths ranging from very shallow (supratidal zone) to bathyal.

The distribution of tempestites in relation to the depositional axis, in terms of proximality, produces distinct deposit characteristics. Proximal tempestites display a larger grain size; thick, amalgamated layers; a predominance of swaley over hummocky cross­stratification; a greater frequency of channels; and offshore oriented paleocurrents. Distal tempestites are thin­bedded, and thus often confused with turbidites; this type is further characterized by finer granulation, sole marks, and alongshore paleo-currents.

The primary depositional geo-metry of tempestites is that of lobes or sand sheets. Elongated shapes, corresponding to sand ridges or offshore bars, may later be generated by reworking processes during relative sea­level lowstands.

In the overwhelming majority of cases, the facies sequence coarsens and thickens upwards, and variations in relative sea level are responsible for the formation of this vertical succession.

Despite the debate surrounding the genesis of tempestites (i.e., whether turbidity currents were present as the main depositional agent), there is no question as to the similarity of this structure to turbidites. In this thesis, I have used the turbidite facies of Mutti & Ricci­Lucchi for the characterization and mapping of tempestites.

The relation between tempestites and certain causes, such as hurricanes, winter storms, or tsunamis, is still far from being definitively clarified. In human dimensions, major storms occur very rarely, that is, around once every one thousand years; furthermore, the magnitude and periodicity of episodic geological events, of which major storms are an example, depend on factors that have varied over geological time, thus placing limitations on the use of uniform-itarianism in the interpretation of tempestites.

The tempestites of the Parnaíba Basin were studied within the framework of sequence stratigraphy, a modern stratigraphic methodology. Based on the establishment of fifty­two electric markers and on a number of other parameters, depositional sequences denominated the Devonian, Devonian­Mississippian, Mississippian, Pennsylvanian, and Permian sequences were defined. Tempestites are found to occur principally in the muddy sections of these sequences, in the transgressive interval and base of the regressive interval, near the maximum flood surface of the sequence. Isopach maps reveal tectonic control from ancient lineaments generated in Pre­Silurian precursor rifts. Isolith maps show source areas to have been located mainly to the east of the basin. In terms of facies, proximality, and the constitution of the facies sequence, all character-istics seen in tempestites elsewhere around the world can be identified in the Parnaíba Basin.

There is an excellent global correlation between the depositional sequences of the Parnaíba Basin and those of the Northern Hemisphere, the Amazonas Basin, and Ghana offshore. The level that correlates best is the maximum transgressive surface of the Frasnian, corresponding to a global event of high organic productivity and profound alteration in the hydros-phere­atmosphere relation, in terms of CO2.

It is concluded that the abundance of tempestites in the Parnaíba is the result of the ancient situation of this basin, located in a seaway positioned between the limits of northern part of the African and South American continents and connected to the Thetis paleo­ocean. Similarly to the Cretaceous Western interior Seaway, it is hypothesized that the existence of a subtropical high­pressure cell at the mouth of the Parnaíba Seaway prompted the penetration of hurricanes that superposed themselves on extra­tropical cyclones at high altitudes, thus spawning the major storms (characterized by waves over ten­meter high) that produced the tempestites.

In economic terms and in terms of hydrocarbon exploration, it can be postulated that these tempestites, and mainly those located in the regressive intervals of the sequences, will become an important stratigraphic prospect within the Parnaíba Basin, today at an incipient exploration stage.

GEOLOGIA SEDIMENTAR E PALEOGEOGRAFIA DO NEOPERMIANO E EOTRIÁSSICO (INTERVALO KAZANIANO­SCYTHIANO) DA BACIA DO PARANÁ

LATE PERMIAN AND EARLY TRIASSIC (KAZANIAN­SCYTHIAN INTERVAL) SEDIMENTARY GEOLOGY AND PALAEOGEOGRAPHY OF THE PARANÁ BASIN

Ernesto Luiz Correa Lavina (1991)

Adviser: Mário C. Barberena

Abstract

The end of the Paleozoic and the onset of the Mesozoic were times of remarkable planetary transformations. A trend towards the joining of continental masses modified the Paleozoic paleogeography, formerly characterized by the existence of "small" continents (with the exception of Gondwana). This process culminated with the formation of the Pangea super­continent at the end of the Permian and begining of the Triassic. In parallel fashion, the once well­defined Paleozoic climatic compartimentalization, produced by a high temperature gradient from equator to poles and development of polar ice, gave room to a Mesozoic hot and uniform climate, with no polar ice and exhibiting a low temperature gradient. In this scenario of great changes, the Permian represents a transitional phase. It starts by a generalized glaciation over the southern half of Gondwana, which in association with the compressive tectonic Hercinian episode produced high continents and a sea level eustatically low. As a consequence, the low latitudes of Pangea experienced an extensive desertification. It is possible that the "green house effect", provoked by Hercinian volcanism during Sakmarian time, determined the ice withdrawal in almost all of the gondwanic regions, causing the advance of the sea over the continents, so that a great development of epicontinental seas occurred during Middle Permian time. Owing to a new compressive tectonic episode (Late Hercinian) the borders of Pangea exhibited more or less generalized uplifts, which sectioned the epicontinental seas. It was then accentuated the desertification in the western half of Pangea at latitudes between 30°N and 30°S and monsoonal climates were established in the eastern half, at the promontories of Asia and Australia. During this time, the zones of higher humidity were situated above the 70° latitude. The pos-sibility on an increasing of the "green house effect" during tardi­Hercinian times seems adequate to explain the temperate to cool temperate climate pattern installed in the polar regions, leading to the development of forests and generation of coals.

At the begining of Triassic times, the stabilization of a new climatic pattern allowed the Lystrosaurus fauna to live at high latitudes such as 80°. This pattern of climate and temperature persisted along the duration of Pangea, being supressed only when the super­ ­continent was fragmented in the Upper Jurassic. During Permian times, since the glaciation, and mainly due to the retraction of shallow seas, the faunistic diversity exhibited a sharp decline, considered as the largest ever to occur during the Phanerozoic.

The above mentioned Permian modifications in climate and tectonics affected the area of the Paraná Basin, as testified by its sedimentary facies and depositional systems. The presence of ice characterized the onset of Lower Permian times; later on, associated to the post­Sakmarian transgressions, the following appearance of forests provided the generation of coals in Rio Grande do Sul and Santa Catarina areas. During the episode of maximum flood, a large body of water extended over the whole region of Paraná, Chaco­Paraná and Karoo Basins, where the betuminous shales of Irati, Chacabuco and Whitehill Formations deposited. The area corresponding to this sea was significatively larger then the one nowadays preserved. As a consequence of the large extension and high coastal onlap, the arrival of terrigenous sediments was precluded, causing the generation of a very extended condensed section. Stratification of the water column was then established, determining the presence of a thermocline which separated the colder bottom waters, rich of nutrients, with higher density and oxygen­deficient, from the warmer, well­oxygenized and low­density surface waters. Thus, an abundant life was favoured by the later, whereas anoxic environments at the bottom provided the accumulation of organic elements, leading to the deposition of lipid­enriched shales.

These environmental conditions ceased during the tardi­Hercinian tectonic activity, by the sectioning of the Pacific oceanic arm which regulated the water disposability for the basin. As a consequence, the Whitehill­Irati sea changed to a huge lake (or inner sea), becoming the depositional area for the Serra Alta and Teresina Formations. The decrease of geographic extension and mean deepness broke the stratification of the water column; anoxic conditions were supressed and the bottom waters became only moderately oxigen­deficient. Increasing aridity determined geographic restriction and, later on, the establishment of gently arched regions led to the compartmentalization of the main water body into a series of smaller lakes, though large enough at the begining of the process (Rio do Rasto Formation).

Although strong oscillations in water availableness occurred, the trend to an increasing aridity dominated, culminating with the desertification of the whole Paraná Basin in the Upper Tatarian/Lower Scythian (Buena Vista, Sanga do Cabral and Piramboia Formations). At this time, humid environments were restricted to South Africa, but probably included in a larger­scale semi­arid context.

ESTRATIGRAFIA, SEDIMENTAÇÃO E DIAGÊNESE DOS ARENITOS DA FORMAÇÃO SERRARIA, CRETÁCEO INFERIOR DA BACIA SERGIPE­ALAGOAS, NORDESTE DO BRASIL

STRATIGRAPHY, SEDIMENTATION AND DIAGENESIS OF THE SANDSTONES FROM THE SERRARIA FORMATION, LOWER CRETACEOUS OF THE SERGIPE­ALAGOAS BASIN, NORTHEASTERN BRAZIL

Antônio Jorge Vasconcellos Garcia (1991)

Adviser: Natálio Gamermann

Associated Adviser: Chang Hung Kiang

Abstract

A multidisciplinar analysis of the Serraria Formation allowed a re­evaluation of the pre­rift sequence in coastal and interior basins in northeastern Brazil and western Africa with the resulting new definition of the Afro­Brazilian Depression.

The palaeogeographic characterization of several sedimentological evolutionary phases of the Serraria and Sergi Formations was vital to establish their source areas as well as a better understanding of the distribution of the arboreal vegetation. Silicified wood of this vegetation occurs in those units in Sergipe­Alagoas Basin and in the north part of Tucano Basin.

The prevailing climatic conditions in the Gondwana Continent and types of the sedimentary deposits point out the Afro­Brazilian Depression as a peridesertic region with endorreic and assimetric drainage. Efemerous braided rivers crossed this vast region in periodic torrents and, allied with local eolian and lacustrine deposits, provided the gradual filling of the palaeobasin.

In the north portion of the Depression, the best conditions of atmospheric precipitation allowed the development of a braided fluvial stream over a large extension, from headwaters in the Rio do Peixe region to distal portions in Sergipe­Alagoas Basin. However, in the southern portion, Recôncavo region, a greater distribution of eolian deposits occurred, owing to most intense aridity conditions.

I propose an integrated depositional model which involves the Antenor Navarro Formation of the Rio do Peixe Basin (proximal fluvial facies), the Serraria Formation (intermediate to distal fluvial facies) and the Bananeiras Formation (distal lacustrine facies) of the Sergipe­Alagoas Basin. The Etosha Pan in Namíbia, in a peridesertic situation in respect to Kalahari Desert, and the Eire Lake Depression in Australia are present­day analogous models.

Based on detailed sedimentological analysis the Serraria Formation can be divided into three lithological intervals, from the bottom to the top: 1) interbedded fine­grained sand-stones and shales (AFBPI), transitional to the shales of the Bananeiras Formation, 2) mid- to coarse-grained sandstones and con-glomerates (AMGC), and 3) fine­grained sandstones with intercalation of shales (AFPTI), transitional to the Barra de Itiúba Formation. Mid- to coarse-grained sandstones, called "Caioba Sandstone", also occur interbedded in the latter interval.

The sandy intermediate interval is possible to subdivide into three lithological units, each of them corresponding to an important evolutive aspect: a) a fluvial lower unit of mid­ to coarse­grained sandstones (AMGI), b) an eolian intermediate unit of fine­ to mid­grained sandstones (AE), and c) a fluvial upper unit of coarse­grained sandstones and conglomerates (AGCS). The eolian lithological unit has not been well developed and was strongly affected by erosion processes during the deposition of the AGCS unit.

A better approach on palaeoclimatic and palaeoecologic aspects during the sedimentation of the Serraria Formation is based on the study of the palaeontological material discovered in the Serraria Formation sandstones (silicified wood of gymnospermae and angyospermae) and in the underlying and overlying litho-stratigraphic units (scales of the genus Lepidotes, fragments of a hybodontid shark, and mollusk shells).

The mass balance of the eroded material from the most probably sedimentary source area and the deposited material in the north­central part of the basin allow to speculate that the sedimentation of the Serraria and the Sergi Formation took place under 10 Ma during the Lower Cretaceous, probably the Berrisian.

The petrological analysis of the sandstones permitted the definition of four diagenetic domains. Depositional conditions, burial history and geochemical characteristics of source rocks were responsible for the differentiation of these diagenetic domains.

Diagenetic domains 1, 2, and 3 (Caioba, Atalaia Sul, Aracaju, Carmópolis, Robalo and Japoatã­Penedo sectors), situated at the most distal portions of the depositional system, display ferrous and non­ferrous dolomite as the principal eodiagenetic cement. On the other hand, in domain 4, in the São Miguel dos Campos Platform, the eodiagenetic cement is calcite. On this way, the eodiagenetic fluid conditions varied from saturated alkaline in respect to calcite (median portion of the fluvial system) to saturated dolomite in respect to the dolomite (distal portion of the fluvial system). Such conditions point out to an increase of the Mg/Ca ratio (continental sabkha). The meso-diagenetic carbonate composition has a direct relation to the regional compositional zoning of the eodia-genetic carbonate, i.e., a kind of heritage with respect to the original distribution.

The burial history of the three first diagenetic domains is characterized by uplift phases, with local exposition of the Serraria Formation during the pre­Muribeca unconformity (actually, this unit is exposed in domain 3). Infiltrations of the meteoric fluids during these phases played a very important role on the diagenetic evolution of the sandstones, with the production of: generalized dissolution of feldspars, intraclasts and micas with caolinization; significative removing of the carbonate cements with important production of secondary porosity (until 20%); oxidation of previous ferrous phases (ferrous dolomite and pyrite); and degradation of hydrocarbon compounds. The replacement of subarkoses sandstones by "diagenetic quartz sandstones" (980 2F OL) are formed as a result of high dissolution of framework grains in these domains. After the uplift phases, the lithological units of such domains suffered a new burial phase, when higher temperatures than those of the first mesodiagenesis dominated.

Although diagenetic domain 4 does not show a telodiagenesis during the burial history of the Serraria Formation, a very important mesodiagenetic aspect is described, i.e., a significative albitization of feldspars (plagioclase and K­feldspat), specially at the top of this unit. The sandstone porosity values of domain 4 are around 10%.

Intensity of clay mineral mechanic infiltration during the eodiagenesis (more intense in domains 3 and 4), the crushing of intraclasts, with pseudomatrix production, and the development of secondary quartz overgrowth are other important diagenetic processes for definition of reservoir characteristics of the Serraria sandstones.

In diagenetic domains 1, 2, and 3, organic solutions and hydrocarbons generated from continental and marine source­rocks percolated through Serraria reservoirs. Otherwise, in domain 4, there are just continental source­rocks.

I suggest additional studies with the proposal to improve the presented palaeogeographic and palaeoclimatic models for the pre­rift sequence as well as to get a better approach of the geochemical aspects associated with the diagenetic processes in the Serraria Formation (such as eodiagenetic cementation, telodiagenetic dissolution, albitization, and so forth).

CARACTERIZAÇÃO SEDIMENTAR DE PARTE DO SISTEMA DEPOSICIONAL LEQUES ALUVIAIS DA PROVÍNCIA COSTEIRA DO RIO GRANDE DO SUL

SEDIMENTARY CHARACTERIZATION OF A PART OF THE ALLUVIAL FANS DEPOSITIONAL SYSTEM IN THE COASTAL PROVINCE OF RIO GRANDE DO SUL

Loreci Gislaine de Oliveira Lehugeur (1992)

Adviser: Inês Leonida da Rosa Martins

Abstract

The alluvial fans laid down in the Rio Grande Coastal Province stem from desagregation and decomposition of granit rocks. They display overlapped lobes related to several outflows.

The textural heterogeneity of the sediments is marked by the ample interval that goes from pebbles to clay. The grain size decreases towards the fan distal area, which is better observed in its northern region.

The mineralogical content of the sediments is basically granite, feldspar, mica and clay minerals.

The depositional processes responsible by the transport and deposition of the sediments are the debris flow, current flow and mud flow, with predominance of the first.

The outstanding facies present in the deposits are the conglomeratic sandstones, sandy­clay sedimentswith granules, and clay sediments carrying out massive internal structures with either normal or inverse graded bedding and planar cross­stratification. The bedding internal features are related to depositional mechanism and processes.

The driving energy during the sediment transport and deposition varied according to each studied region, but the fluidity index remained always high.

Sedimentological evidences worked out the occurrence of arid climate intercalated with hot and humid periods during the transport and deposition of the sediments. These climatic alternances are correlated to the Pleistocene glacio­eustatic variations of the sea level.

The alluvial fan system has been stratigraphically recorded as Upper Tertiary - Lower Quaternary.

ANÁLISE ESTRATIGRÁFICA DO TERCIÁRIO INFERIOR DA BACIA DE CAMPOS - UMA VISÃO MODERNA (COM ÊNFASE NA REGIÃO DOS CAMPOS PETROLÍFEROS DE CORVINA E MALHADO)

STRATIGRAPHIC ANALYSIS OF THE LOWER TERTIARY IN CAMPOS BASIN - A MODERN VIEW (WITH EMPHASIS ON PETROLIFEROUS OIL FIELDS OF CORVINA AND MALHADO)

Julio Cesar Scarton (1993)

Adviser: Antonio Manuel Figueiredo

Abstract

The stratigraphy of the Lower Tertiary sedimentary package, in the central area of Campos Basin, offshore the southeastern Brazilian margin, is analyzed in great detail, in order to establish the viability to use the Sequence Stratigraphy concept and methodology to interpret the sedimentary facies; to define depositional paleoenvironments; to explain the abundant presence of glauconite in turbidites and to interpret isotopic data.

The research area, with aproximately 350 km², whose water depth ranges from 100m to 800m, encompasses the Corvina and Malhado oil fields.

The studied interval, pertaining to the Paleocene, Eocene and Early Oligocene epochs, was divided into six third order stratigraphic sequences called P1, P2 and P3 (Paleocene) and EI, EII and EIII (Eocene and Early Oligocene). These stratigraphic sequences are related to relative sea level variations strongly influenced by tectonic and volcanic events. The isotopic studies (13 and 18 O) corroborate the interpretation of a sea level fluctuation.

Analysis of aproximately 255m of cores from 17 wells allowed the identification of eleven descriptive sedimentary facies (Fd - Diamictite facies; Fca - Algalic calcirudite facies; Fcp - Polimitic conglomerate facies; Fci - Intraformational conglomeratic facies; Fcb - Bioclastic calcarenitic facies; Fam - Massive sandstone facies; Fax - Glauconitic sandstone with cross­stratification facies; Fab - Bioturbated sandstone facies; Fal - Laminated sandstone facies; Fp - Pelitic facies; Paf - Bioturbated and interbedded sandstone/mudstone (turbidites reworked by bottom currents - contourites). These facies are arranged in genetic facies scheme. The turbiditic systems could be reworked by botton currents and this fact is evidenced by the exotic character presented by Fab of Faf facies.

The subaqueous gravitational systems are related to the lowstand systems tracts associated to each stratigraphic sequence. In a regional scenario it is inserted in a channel­lobe transition area. The channels show structural (halokinetic) control and were enlarged by turbiditc currents and possibly by bottom currents also.

The paleoecological studies made with benthonic foraminifera and ichnofossils characterize a middle bathyal paleoenvironment for the deposition of stratigraphic sequences and associated turbiditic systems.

PhD T H E S E S - MARINE GEOLOGY:

ASPECTOS DA SEDIMENTAÇÃO NA REGIÃO NORDESTE DA LAGOA DOS PATOS: LAGOA DO CASAMENTO E SACO DO COCURUTO - RS - BRASIL

ASPECTS OF THE SEDIMENTATION IN THE NORTHEASTERN PART OF THE LAGOA DOS PATOS: LAGOA DO CASAMENTO AND SACO DO COCURUTO, RS, BRAZIL

Jorge Alberto Villwock (1977)

Adviser: Luiz Roberto Silva Martins

Abstract

The Lagoa dos Patos had its formation conditioned by the develop-ment of a multiple sandy barrier, under the influence of eustatic oscillations occurred during the Quaternary.

Geomorphologic aspects of the lagoonal margin of this barrier indicate the existence of at least four transgressive and regressive cycles. The accompanying sedimentary pro-cesses caused the compartmentation of the lagoon through the growth of sandy spits, a mechanism which gave origin to the Lagoa do Casamento and Saco do Cocuruto.

The bottom sediments of these lagoonal bodies are sandy and siltic. The sandy facies occur on the marginal and shallow parts, having their textural characteristics influenced by the kind of material derived from the source area, as well as by the nature, intensity and the time related to the action of the sedimentary agents. The siltic facies occupy the central and deeper positions. Sandy - siltic and siltic - sandy facies lay over the surface of the intermediary zones.

Quaternary terrains of the lagoonal margin, reworked during the transgressive cycles, constitute the main source of the lagoonal sediments. The Lagoa dos Patos waters, when entering the Lagoa do Casamento, bring into suspension a part of the siltic material originated from the highlands that border the Coastal Province.

Main agents involved in the sedimentation processes are the wind, waves and lagoonal currents. The water circulation is also influenced by the fluvial systems acting on the region.

The sedimentation is processed within an environment of shallow and fresh waters, lightly acidic, oxidizing at the margins and weakly reducing on the central parts. The benthonic biologic activity is scarse and related to a small fauna of mollusks.

The geomorphological evolution of the area controlled the major aspects of sedimentation in the lagoonal body.

Attempts to environmental characterization based on granulometric analyses evidenced that the methods of Folk & Ward (1957), Passega & Byranjee (1969) e Doeglas (1968) are efectively useful for the description and interpretation of present sedimentary environments, provided that the physical parameters are known. However, their usage as the only criteria for paleoenvironmental determination introduces a bias, since sedimentation on a coastal province is polycyclic and promoted by several defined environments which are moveable in time and space. Very often, the fast reworking of materials deposited under high energy environments is unable of erasing the textural characteristics inherited from the precedent cycle. The larger part of sediments of sandy facies from the lagoonal bottom exhibit properties similar to those deposited in beach and eolian environments.

INTERPRETAÇÃO PALEOAMBIENTAL DA SEQÜÊNCIA PÓS­EVAPORÍTICA DA PORÇÃO SUL DA BACIA DO ESPÍRITO SANTO - ES - BRASIL

PALEOENVIRONMENTAL INTERPRETATION OF THE POST­EVAPORITIC SEQUENCE OF THE SOUTHERN PART OF THE ESPÍRITO SANTO BASIN - ES - BRAZIL

Maria Antonieta da Conceição Rodrigues (1982)

Adviser: Renato Rodolfo Andreis

Associated Adviser: Josué Camargo Mendes

Abstract

The post­evaporitic sequence of the southern part of Espírito Santo Basin, one of the most typical basins of the Brazilian eastern coast, is studied here.

The material of three drilling cores (1­ESS­5, 1­ESS­22 and 1­ESS­23) kindly lent by Petróleo Brasileiro S.A. - PETROBRAS was studied.

The data obtained from the three drillings were integrated into columnar profiles, for a better visualization of the results.

Lithostratigraphic units were characterized, after the lithologic description of the studied sections was accomplished.

Eleven biozones, based on foraminifera, were recognized. One of them is related to the Upper Cretaceous; the remaining ones to the Tertiary.

Palaeoenvironments were established for the lithofaciologic units, according to the most diagnostic features of the studied lithofacies, such as granulometry, sedimentary structures, colours and distribution of the microfossils.

MODELO SEDIMENTAR DO CONE DO RIO GRANDE

SEDIMENTARY MODEL OF THE RIO GRANDE CONE

Inês Leonida da Rosa Martins (1983)

Adviser: Luiz Roberto Silva Martins

Associated Adviser: Carlos Maria Urien

Abstract

The main object of this thesis was the study the sedimentary model of the Rio Grande Cone, located at the Continental Margin of the State of Rio Grande do Sul (Brazil).

Twenty­three cores collected in the region, amounting to 134 meters, were analyzed in respect to textural, mineralogical and depositional properties.

Aspects related to the regional geology, the stratigraphy of the Pelotas Basin, the evolution of the South Atlantic Continental Margin, the oceanic currents and the physical properties of water masses were studied and revised in order to offer a better understanding of the area studied.

The more prominent depositional processes usually at work on the continental slope were analyzed together with the results obtained through the study of the cone sediments.

The Rio Grande do Sul Cone is a deep sea feature of typical sedimentary origin which began to be formed in the Upper Miocene, produced by the accumulation of predominantly pelitic terrigenous material from the drainage of the La Plata River and the highlands of Rio Grande do Sul.

This typical progradational sedimentary sequence was submitted to downslope gravitacional movements (turbidity currents and other movements) and modelling through geostrophic contour currents which are responsible for the conturite beds occurring in all sedimentary cones.

The relationship between the studied depocenter, the drainage responsible for its main sediment supply and the existing dynamics in the sea during the Wisconsin offered strong evidence for the identification of the Quaternary paleogeographic evolution of the South Atlantic Continental Margin.

On the other hand, the physiography and the sedimentary evolution of this area produced a slope sedimentation extremely rich in organic matter.

The present study offers new elements to identify older sedimentary sequences.

CONTRIBUIÇÃO AO ESTUDO DOS SISTEMAS DEPOSICIONAIS HOLOCÊNICOS DO NORDESTE DA PROVÍNCIA COSTEIRA DO RIO GRANDE DO SUL, COM ÊNFASE NO SISTEMA EÓLICO

CONTRIBUTION TO THE STUDY OF THE HOLOCENE DEPOSITIONAL SYSTEMS FROM THE NORTHEASTERN COASTAL PROVINCE OF RIO GRANDE DO SUL, WITH EMPHASIS ON THE EOLIAN SYSTEM

Luiz José Tomazelli (1990)

Adviser: Jorge Alberto Villwock

Abstract

The Holocene depositional systems of the NE part of the Rio Grande do Sul Coastal Province (Lagoon, Eolian and Beach Systems) were studied from two points of view. On the geologic perspective they were treated as sedimentary environments responsible for the generation of an important assemblage of sedimentary facies. On the human point of view they were considered as a complex environment, fragile and dynamic, where multiple processes take place, associated with the sea, land, atmosphere and life.

The Lagoonal System comprises a group of depositional environments and sub­environments (lagoons, lakes, meandering rivers, inter­lagoonal meandering channels, fluvio­lagoonal deltas, "lagoonal­tidal" deltas, swamps) developed on the lowlands between the Holocene barrier and the Pleistocene terrains. The sedimentary processes acting in these environments, the morphologic patterns developed, the distribution of the sediments and the evolution through time are investigated in this study.

The Eolian System was studied with more detail, owing to its great importance. It is controlled by a wind regime of high energy and low directional variability that blows dominantly from the northeast. The sand drift potential was calculated from the velocity and directional data registered at the meteorologic stations. The eolian features were classified on a genetic and descriptive basis and studied in their morphological aspects and internal organization. The free dunes, important elements of the system, show a net migration to the southwest with rates between 10 and 38 m/year, according to determinations conducted directly on land and by aereal photographs analysis.

The Beach System, controlled basically by the wave action, is represented by a long, almost rectilinear and morphologically very uniform sandy beach which shows a dissipative behaviour most of the time. It usually has a "morphological state" that reflects the strong influence of the storms, making the beach profile completely flat and develops a persistent scarp in the frontal dunes. Several evidences show that in this system the erosional processes predominate over the depositional ones.

We tried in this study to know the processes that have acted on these coastal systems since their generation at the end of the great Holocene transgression until now. We have intended to understand their evolution during the Holocene, their nowadays behaviour and their future perspectives. In this context we verified that at the present this coastal region is submitted to a transgressive process that has reverted its previous tendency to progradation. This transgressive event that affects and interconnects all the coastal systems seems to be the most important process working in this coastal region nowadays.

AVALIAÇÃO DAS MUDANÇAS DO NÍVEL DO MAR DURANTE O HOLOCENO NA PLATAFORMA CONTINENTAL ADJACENTE AO RIO DE LA PLATA

EVALUATION OF THE SEA LEVEL CHANGES DURING THE HOLOCENE IN THE CONTINENTAL SHELF ADJACENT TO THE LA PLATA RIVER

Ricardo Norberto Ayup Zouain (1991)

Adviser: Luiz Roberto Silva Martins

Abstract

The sedimentological and miner-alogical study of the superficial bottom samples of sediments of the Rio de la Plata and adjacent continental shelf was developed to characterize the paleogeographic evolution of this area.

Textural parameters were obtained and analyzed by simple and multivariate statistic methods (cluster analysis and discriminant functions). This study allowed to establish the differents dynamic processes developed in the area.

The heavy minerals composition of the sands from the continental shelf adjacent to the Rio de la Plata, was determined by multivariate statistic methods (cluster analysis, principal components analysis and Q­mode factor analysis) in order to examine the causes of the probable dynamic conditions.

The results of the study of the relation between multivariate analysis and traditional analysis with morpho-logical aspects, have demonstrated that much of the continental shelf sand composition is in part relict, reflecting along and cross­coast­shelf sand movement associated with different sources.

The sea level rise and accompanying migration of paleo­coastlines, permitted to establish the Holocene paleographical evolution for this area.

Different positions of the paleo­coastlines level are located about 22/23m, 30­40 and 60­75m deep, and the rise of these different levels was developed previously to 11,000 years B.P. until 6,000 years B.P.

CALCISFERAS E MICROFÁCIES EM ROCHAS CARBONÁTICAS PELÁGICAS MESOCRETÁCEAS

Dias-Brito,D. 1995. Calcisferas e microfácies em rochas carbonáticas pelágicas mesocretáceas. Tese de doutorado, Curso de Pós-Graduação em Geociências, Universidade Federal do Rio Grande do Sul. 3 vol.

DIMAS DIAS BRITO

Orientador: DOUTORADO DIRETAMENTE POR DEFESA DE TESE

BancaExaminadores:
Prof. Dr. Jorge Carlos Della Fávera
Dr. Luiz Antonio Pierantoni Gambôa
Prof. Dr. Paul Edwin Potter
Prof. Dr. Setembrino Petri
Profa. Dra. Yvonne Terezinha Sanguintetti

Data:    /    / 1995

Palavras Chave: calcisferas; calcisferulidos; Pithonelloideae; Cretáceo; rochas carbonáticas pelágicas;microfácies;Atlântico Sul; Brasil; Tétis.

Resumo

Esta tese inclui um estudo global envolvendo as calcisferas mesozóicas (com ênfase especial à subfamília Pithonelloideae Keupp, 1987, dinoflagelados calcários), sua ocorrência em sedimentos carbonáticos pelágicos do Cretáceo médio da Margem Atlântica Brasileira e um Atlas que compreende microfácies e os fósseis destas rochas.
A primeira parte trata de organizar, de forma compreensível, a evolução das pesquisas em torno das calcisferas, especialmente no que se refere aos pitonelóideos (classicamente referidos como calcisferulidos). No que diz respeito a estes organismos, mais de 100 referências foram analisadas, incluindo praticamente todos os artigos publicados desde o século passado, o que permitiu a elaboração de uma síntese exaustiva incluindo sua paleoecologia, estratigrafia e paleobiogeografia. Um grande número de diagramas permite perceber a distribuição estratigráfica e biogeográfica global desta subfamília cretácea e de seus diferentes taxa no intervalo Albiano-Maastrichtiano, andar a andar. A  conclusão mais importante desta revisão é que os Pithonelloideae tiveram seu climax em todo o mundo em simultaneidade com a fase de mar mais alto de todo o Cretáceo, i. e., do neo-Albiano ao Coniaciano. Visualizou-se, por outro lado, a existência de uma forte conexão entre a massa d'água tépida e excessivamente salgada do Tétis mesocretáceo e o apogeu destes organismos oportunistas.
Na segunda parte, dez bacias costeiras, distribuídas nas margens leste e equatorial do Brasil, foram examinadas a partir de dezenove poços. Mais de 1000 lâminas delgadas, obtidas essencialmente a partir de material testemunhado, foram investigadas e mais de 5000 espécimens de calcisferas foram observados com o auxílio do microscópio eletrônico de varredura. As bacias portadoras de carbonatos tropicais extendem-se para o norte, a partir da Plataforma de Florianópolis, constituindo a borda oeste do Atlântico Sul setentrional. A subfamília Pithonelloideae está representada por cinco taxa (Pithonella sphaerica, P. ovalis, P. trejoi, P. cf. P. perlonga e Bonetocardiella conoidea). A abundância destas espécies nos carbonatos pelágicos neríticos destas bacias varia consideravelmente, sendo que a maior produtividade do grupo está registrada em estratos do Albiano superior, sobretudo nas bacias de Campos, Espírito Santo, Santos e Barreirinhas. Em vários níveis deste intervalo eles estão associados a radiolários, evidenciando ressurgências costeiras. Outros resultados importantes incluem o reconhecimento das amplitudes estratigráficas dos Pithonelloideae ao longo da costa brasileira, sua comparação com outras seções distantes, estimativas paleobatimétricas das áreas investigadas e alta incidência de redeposição dos greditos albianos, cujos componentes planctogênicos são essencialmente os mesmos dos chalkstones da Europa e da América do Norte. O estudo da Margem Atlântica Brasilieira também mostrou que o Atlântico Sul setentrional primitivo (neo-Aptiano a Albiano) surgiu como um longo e estreito braço do Tétis, aqui designado "Tétis Sul-Atlantiano". Já em tempos cenomanianos, tal entidade não mais ocorria de forma íntegra. O Tétis, na concepção de um domínio de águas quentes, teve, por outro lado, seus limites globais mesocretáceos aqui ampliados.
O Atlas, com 101 estampas e 634 fotomicrografias, resultou de pesquisas aos microscópio ótico e eletrônico de varredura. Nele, o conteúdo organogênico essencial dos carbonatos pelágicos do Cretáceo médio do Brasil é mostrado, estabelecendo-se para o intervalo Albiano-Turoniano 28 diferentes microfácies. Estas microfácies, incluindo calcários e margas argilosas, são definidas por variações nos teores de material terrígeno e calcário e pela quantidade e variedade dos microfósseis planctônicos. Refletindo diferentes massas d'água, os conjuntos microfaciológicos oferecem um boa alternativa para estudos de bacia que envolvam comparações e investigações paleoecológicas/paleobatimétricas de seqüências carbonáticas mesocretáceas de mar aberto.

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CALCISPHERES AND MICROFACIES FROM MID-CRETACEOUS PELAGIC CARBONATE ROCKS

Key Words: calcispheres;calcisphaerulids; Pithonelloideae; Cretaceous; pelagic carbonate rocks; microfacies;  South Atlantic;Brazil; Tethys.

Abstract

A global study of Mesozoic calcispheres (especially the subfamily Pithonelloideae Keupp, 1987, calcareous dinoflagellates), their occurence in the mid Cretaceous pelagic carbonates rocks of the Brazilian Atlantic margin, and an Atlas of microfacies and fossils and their significance are the subjects of this thesis.
The first part focuses on the widely dispersed literature of Mesozoic calcispheres, particularly the subfamily Pithonelloideae, whose components are classically called "calcisphaerulids". More than 100 references about pithonelloids were reviewed dating from the last century and an exhaustive syntesis was made of their paleoecology, stratigraphic ranges, and paleobiogeography. Many diagrams of global  stratigraphy and biogeography of the Cretaceous subfamily and its different taxa are presented stage by stage from the Albian to the Maastrichtian. The most important conclusion from this review is that the Pithonelloideae climaxed simultaneously all over the world during the highest of all the Cretaceous sea levels in late Albian to Coniacian time. A strong association also exists between the maximum temperature and the salinity of the Tethyan water mass and the acme of the opportunistic  Pithonelloideae.
In the second part, nineteen wells were examinated in ten of Brazil's offshore basins all along its coast. Over 1000 thin sections were made from core samples, and more than 5000 specimens of calcispheres were observed with the S.E.M. The basins having tropical carbonates extend northward from the São Paulo Plateau/Walvis Ridge and belong to the northern part of the South Atlantic Ocean. The subfamily Pithonelloideae is mostly represented by five taxa (Pithonella sphaerica, P. ovalis, P. trejoi, P. cf. perlonga and Bonetocardiella conoidea). These vary greatly in abundance in the neritic pelagic carbonates of Brazil's offshore. They are most abundant in the upper Albian of the Campos, Santos, Espírito Santo and Barreirinhas basins, where there are also many radiolarians and some black shales. Coastal upwelling is infered. Other important results include the stratigraphic ranges of the Pithonelloideae throughout the Brazilian Margin and their comparison with other sections abroad, the bathymetric evolution of each basin, and the high incidence of redeposition of their Albian chalkstones, whose planktogenic content is essentially the same of the European and North American ones. The study of the Brazilian margin also showed that the Tethyan ocean clearly extended south to the São Paulo Plateau/Walvis Ridge during Late Aptian-Albian and that during this time the primitive northern South Atlantic was a long and narrow arm of the Tethys, here termed "the South Atlantic Tethys". The idea of a warm Tethys Ocean was also used to revise its Cretaceous worldwide limits.
The Atlas has 101 plates, 634 photomicrographs, and is based on both thin section and S.E.M. studies and displays all the essential fossils of the Brazilian mid Cretaceous pelagic carbonates. The established 28 different Albian-Turonian microfacies are defined by variations of terrigenous and calcareous material and by the quantity and kind of planktonic microfossils. These new microfacies include the types and  significance of fine-grained limestones and marls and provide a consistent and easy way to estimate the paleobathimetry and paleoecology of mid Cretaceous pelagic carbonates. It is hoped that the new methodology used in this atlas will facilitate more comparative studies of open sea carbonates  everywhere.

BIOCLASTOS DE ORGANISMOS TERRESTRES E MARINHOS NA PRAIA E PLATAFORMA INTERNA DO RIO GRANDE DO SUL: NATUREZA, DISTRIBUIÇÃO, ORIGEM E SIGNIFICADO GEOLÓGICO

Buchmann,F.S.C. 2002. Bioclastos de organismos terrestres e marinhos na praia e plataforma interna do Rio Grande do Sul: Natureza, distribuição, origem e significado geológico. Tese de Doutorado, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, pp.

FRANCISCO SEKIGUCHI DE CARVALHO BUCHMANN
paleonchico@yahoo.com.br

Data da Defesa: 20/12/2002
Area de Concentração: Geologia marinha
Orientador: Prof. Dr. Luiz José Tomazelli
Banca de Examinadores: Prof. Rodolfo José Angulo (UFPR)  ; Prof. Lauro Júlio Calliari (FURG); Prof. Jorge Ferigollo (PUC)

Palavras-chave: Rio Grande do Sul; oceanografia; Pleistoceno; antepraia; megafauna

RESUMO

Fácies marinhas e costeiras associadas a eventos transgressivos-regressivos quaternários ocorrem na Planície Costeira do Rio Grande do Sul e na plataforma continental adjacente. Enquanto as fácies expostas na planície costeira apresentam uma composição essencialmente siliciclástica, as fácies submersas, hoje aflorantes na antepraia e plataforma interna, apresentam, muitas vezes, uma composição carbonática. Formada por coquinas e arenitos de praia fortemente cimentados, estas fácies destacam-se do fundo oceânico como altos topográficos submersos. Os altos topográficos da antepraia têm atuado como fonte de boa parte dos sedimentos e bioclastos de origem marinha encontrados nas praias da área de estudo. Os bioclastos carbonáticos que ocorrem nestes locais caracterizam uma Associação Heterozoa, ou seja, são formados por carbonatos de águas frias, característicos de médias latitudes, e são representados principalmente por moluscos, equinodermos irregulares, anelídeos,
crustáceos decápodos, restos esqueletais de peixes ósseos e cartilaginosos, cetáceos, tartarugas e aves semelhantes à fauna atual. Além destes bioclastos de origem marinha, as praias estudadas apresentam a ocorrência de fragmentos orgânicos provenientes de afloramentos continentais fossilíferos, contendo abundantes restos esqueletais de mamíferos terrestres gigantes extintos, das ordens Edentada, Notoungulada, Liptoterna, Proboscidea, Artiodactila, Perissodactila, Carnívora e Rodentia. A concentração dos bioclastos na praia resultada da ação direta dos processos hidrodinâmicos que atuam na região de estudo (ondas de tempestade, deriva litorânea, correntes, etc). A variação no tamanho médio dos bioclastos encontrados ao longo da linha de costa está relacionada ao limite da ação das ondas de tempestades sobre o fundo oceânico, o qual é controlado principalmente pela profundidade. Os afloramentos-fonte submersos podem ser divididos em holocênicos e pleistocênicos. A tafonomia d os bioclastos pleistocênicos permite argumentar que após o penúltimo máximo transgressivo que resultou na formação do sistema deposicional Laguna-Barreira III (aproximadamente 120 ka) parte dos depósitos lagunares permaneceram emersos e não estiveram sob a ação marinha (barrancas do arroio Chuí, com a megafauna preservada in situ), enquanto que parte dos depósitos lagunares esteve sob ação direta do ambiente praial. Em diversas feições submersas observam-se coquinas contendo fósseis de mamíferos terrestres, indicando o retrabalhamento dos sedimentos lagunares em ambiente praial. As coquinas que apresentam moluscos pouco 10 arredondados e de maior granulometria são aqui definidas, informalmente, como Coquinas do Tipo 1. Como conseqüência da última regressão pleistocênica (iniciada após o máximo transgressivo de 120 ka) estas coquinas ficaram submetidas a uma exposição subaérea. Este fato possibilitou a dissolução diferenciada dos componentes carbonáticos existentes nos depósitos (coquinas e arenitos) e sua recristalização (calcita espática) em ambientes saturados em água doce. A Transgressão Pós-Glacial (iniciada em torno de 18 ka) foi responsável pelo retrabalhamento dos arenitos e coquinas, recristalizando mais uma vez os elementos carbonáticos. Devido ao seu grau de consolidação estes depósitos resistiram à erosão associada à elaboração da superfície de ravinamento e encontram-se atualmente expostos na antepraia e, mesmo, na linha de praia atual. Pelo menos há 8 ka houve novamente um período favorável à precipitação de carbonato de cálcio, ocorrendo a litificação de rochas sedimentares em uma
linha de praia numa cota batimétrica inferior a atual. Neste intervalo de tempo formaram-se as coquinas e arenitos não recristalizados, apresentando fragmentos de moluscos muito fragmentados e arredondados e de menor granulometria, aqui definidas, informalmente, como Coquinas do Tipo 2. A interpretação da tafonomia dos bioclastos de idade holocênica sugere pelo menos duas fácies deposicionais: (a) Fósseis articulados numa matriz areno-síltica, preenchidos por silte e argila, interpretados como originalmente depositados em regime transgressivo no ambiente Mesolitoral (foreshore) para Infralitoral superior (upper shoreface), com baixa ação de ondas. (b) Fragmentos de carapaças e quelas isoladas encontradas numa coquina fortemente cimentada por calcita espática, por vezes recristalizada, interpretados como concentrados na Zona de Arrebentação por ondas de tempestades. A dinâmica costeira atual retrabalha novamente os sedimentos inconsolidados enquanto as rochas sedimentares co nsolidadas (formadas pelas Coquinas Tipo 1 e 2) resistem parcialmente à erosão e constituem os altos topográficos submersos (parcéis) descritos neste trabalho.

BIOCLASTS OF MARINE AND TERRESTRIAL ORGANISMS IN THE RIO GRANDE DO SUL BEACH AND SHOREFACE: NATURE, DISTRIBUTION, ORIGIN AND GEOLOGY

KeyWords: Rio Grande do Sul; oceanography; Pleistocene; shoreface; megafauna

ABSTRACT

Coastal and marine facies associated to transgressive and regressive events throughout the Quaternary are present along the southern Brazilian coastal plain and inner continental shelf. While the coastal plain facies present a siliciclastic composition, the inner shelf submerged facies are mainly carbonatic. Formed by strongly cemented coquinas and sandstones, these features are present as topographic highs over the seafloor, which has been supplying marine bioclasts and sediments to the beaches in the study area. Such bioclasts are characterized as an Heterozoan Association, a cool water carbonate, composed by: mollusks, irregular equinoderms, annelids, decapod crustaceans, skeletal remains of fish, turtles, whales and birds similar to present day ones. Abundant skeletal remains of extinct terrestrial mammals (Edentada, Notoungulada, Liptoterna, Proboscidea, Artiodactila, Perissodactila, Carnívora e Rodentia) occur. The spatial density of the bioclasts alon g the beach results from direct action of hydrodynamic processes acting in the region (storm waves, longshore drift, currents, etc). The submerged outcrops can be divided in holocenic and pleistocenic. The pleistocenic bioclasts taphonomy allows the argument that after 120 ky, part of the lagoon deposits remained under sub aerial exposure, not being under marine influence, while another part of these deposits was. Coquina deposits present terrestrial mammal bones, indicating surf zone reworking. After 120 ky, the coquinas were exposed allowing a differentiated dissolution of carbonate components within the deposits as well as their recrystallization in fresh water environments (coquina type 1). After 18 ky, marine transgression reworked the deposits, recrystallizing once again the carbonate components. Due to their lithification level, these deposits resisted to erosion and are presently outcropping at the shoreface and foreshore. At 8 ky, another carbonate precipitation eve nt occurred (coquina type 2). The holocenic bioclasts taphonomy interpretation suggests two depositional facies: (a) foreshore and (b) upper shoreface. Modern coastal dynamics reworks again unconsolidated sediments, while sedimentary rocks partially resist and constitute the submerged topographic highs described in this work.

PhD T H E S E S - GEOCHEMISTRY:

ASPECTOS GEOQUÍMICOS E AMBIENTAIS DOS CALCÁRIOS DA FORMAÇÃO PIRABAS - ESTADO DO PARÁ

GEOCHEMICAL AND ENVIRONMENTAL ASPECTS OF THE LIMESTONES FROM THE PIRABAS FORMATION - PARÁ STATE

Jaime Simon Almaraz Urdininea (1978)

Adviser: Milton Luiz Laquintinie Formoso

Abstract

In this thesis are studied various characteristics of the limestones of the Miocenic Formation Pirabas that outcrop in the State of Pará, aiming at characterizing the environment of the sedimentation.

Through a previous appraisal of the stratigraphy of the Tertiary sediments in the region, several stratigraphic maps were developed in order to identify the various tectonic units present, and to define that one responsible for the calcareous sedimentation that has been called Bragantina Shelf.

The petrographic study of eighty five samples of limestone, based on the textural and mineralogical composition, has permitted to reconignize the lithological varieties of these sediments; micritic limestones, dolomicritic limestones and micritic (peletal/squeletal/detritic) limestones. The sedimentological characterization of these rocks by using statistical parameters has led to correlate such parameters with the Bissell & Chilingard's classification and to define the probable energitical levels of the Pirabas sea waters as weakly agitated and calm.

The clay­minerals identified through 471 diffractograms of X­rays and by eventually employing absorption spectrography by infrared rays are the following: kaolinite, illite, ferriferous smectite (nontronite), aluminous smectite (?) and in-terestratified: I(10­14M), I(10­14M). It was observed the relation between the qualitative and quantitative distributions of these clay­minerals and the lithologies with which they are associated. To the first two clay­minerals is assigned a detritical origin, the kaolinite depicting the sialitical process of intense pluviosity in the source areas. The aluminous smectites (?) and the interstratified I(10­14M) are believed to be a new formation in marine and brackish environment of shallow waters. The nontronite and the interstratified I(10­14M) are considered as resulting from diagenesis.

The mineralogy of the carbonates, also studied through 491 difractograms of X­rays, with a register speed of 2° 20/min, in six granulometric intervals, has allowed to identify the following minerals: calcite­ ­with­low­magnesium, aragonite, dolo-mite­with­low­magnesium. The format-ion of calcite­with­low­magnesium is attributed to the paramorphical substitution of the aragonite and of the calcite­with­high­magnesium, and the low content of aragonite in the samples is interpreted as a consequence of the preservation of this mineral under the specifically local lithological conditions. The dolomite is always considered as of secundary origin. The low content of magnesium in the calcite and dolimite areas is interpreted as resulting from the low salinity of the Pirabas Sea waters.

The aplication of "Trend Surface" regression analysis to the three chemical varieties of the limestones composition: calcium oxide insoluble fractions and magnesium oxide, demonstrates a relation of the distribution in area between the two first varieties and the paleogeography of the basin. The magnesium oxid, however, does not obey to the model of such analyses; the more pronounced oscillations present themselves in samples from present littoral areas, being these oscillations minor in continental areas.

The study of distribution in an assemblage of seventeen minor elements and traces in samples of fossil carbonaceous shells, limestones, calciferous shales, insoluble fractions of the calciferous rocks and fractionclay has allowed to regonize the "marine chemiofacies" and the "continental chemiofacies" of the source areas, characterized respectively by the two following groups of elements (1) Sr, B. Cu, V and Ni, (2) Zr, Cr, and Ti. The content variations of B/Ga in the clay and insoluble fractions and of Sr in limestones indicate physicochemical variations in the waters of Pirabas Sea, likely related to salinity changes.

The isotopic ratios O18/O16 and C13/C12 determined in twelve samples of calcareous rocks and thirteen samples of fossils permitted to found a temperature interval of the Pirabas Sea waters between 25 and 30°C (77 86°F), besides revealing the salinity changes befalling in the trans-gression­regression cycle responsible by the sedimentation of these limestones.

A cadastre of the limestone outcrops of Pirabas Formation, Pará State, is shown in the appendix.

PETROGÊNESE DOS GRANULITOS E ULTRAMAFITOS DE LUIZ ALVES (SC)

PETROGENESIS OF THE LUIZ ALVES GRANULITES AND ULTRAMAFITES (SC)

Léo Afrâneo Hartmann (1981)

Adviser: Milton Luiz Laquintinie Formoso

Abstract

The Luiz Alves region is underlain by granulitic rocks, predominantly quartzo­feldspathic and mafic gneisses, and in smaller amounts ultramafites, anorthosites and quartzites, besides small basic dikes. Hypersthene is regionally present in the gneisses and ultramafites herein studied. These rocks are slightly foliated and present granoblastic to granulitic texture. The gneisses show major ­ and minor - element compositions typical of medium­pressure granulites; basic to intermediate gneisses predominate. These granulites are impoverished in lithophile elements, particularly SiO2, K2O, Rb and U. The ultramafites have a basic composition. The gneisses and ultramafites were probably submitted to anatexis, turning it more difficult to identify the pre­metamorphic rock­types; a sedimentary origin for the major part of the rock­pile is favored. The granulite­facies metamorphism occurred 2.7 b.y. ago, during the Jequié Cycle. Lower ages obtained in Pièn are probably due to Rb metassomatism during granite emplacement 600 my ago.

ALTERAÇÃO INTEMPÉRICA DE ROCHAS ULTRABÁSICAS EM CLIMA SUBTROPICAL. EVOLUÇÃO MINERALÓGICA E GEOQUÍMICA DE ALGUNS MACIÇOS ULTRABÁSICOS DO RIO GRANDE DO SUL - BRASIL

WEATHERING ALTERATION OF ULTRABASIC ROCKS UNDER A SUBTROPICAL CLIMATE. MINERALOGICAL AND GEOCHEMICAL EVOLUTION OF SOME ULTRABASIC MASSIFS OF RIO GRANDE DO SUL - BRAZIL

Egydio Menegotto (1982)

Advisers: Milton Luiz Laquintinie Formoso e

Jean­Jacques Trescases

Abstract

The purpose of this thesis is to study the weathering of three Pre­Cambrian ultrabasic massifs which occur in Rio Grande do Sul, Brazil. Such massifs comprise mainly the following rock­types: harzburgitic plagioclase (Pedras Pretas), clinopyroxene­hornblende peridotite (Passo do Ivo), meta­dunite and meta­peridotites (Cerro Mantiqueiras). Metamorphism (amphibolitization and chloritization) and serpentinization affected these rocks in varying proportions.

The environment in which the weathering occurs is characterized by a subtropical climate, with well­defined thermal seasons and a mean annual rainfall of 1,350mm, spread throughout the year. The topography is characterized by hills with gentle slopes, some flat­lying surfaces and rare abrupt scarps. The soil is thin, formed by Lithosoils with small portions of Cambisoils and Brunizem. The vegetation is scarce.

Minerals of lowest stability are weathered (olivine, microcrystalline serpentine, pyroxenes and carbonate) in the first stages. In the saprolite facies, the total weathering of anthophylite, fibrous serpentine of the mesh cords, phlogopite and plagioclase occurs, besides being completed the transformation of clinochlore into secundary chlorite. The other amphiboles (cummingtonite, hornblende, trenolite and actinolite), the serpentine of veins, the talc and the spinels (chromite, magnetite and pleonaste) are scarcely weathered, therefore being abundant in the soil.

The weathering products of the mafic silicates are nontronite and amorphous materials. The weathering of plagioclase forms kaolinite and montmorillonite. The amorphous complex is ferric, whenever plagioclase is absent from the rocks and silicic­aluminous­ferric when it is present. The crystallization of the amorphous materials in the soil forms crystalline oxides and hydroxides of Fe, Mn and Al (mainly goethite), structured as oölites.

The soils originated from ultrabasic rocks are smectitic and with Mg++ as the main exchangeable cation, whereas the soils formed by other rocks, in the same area, are kaolinitic with Ca++ as the exchangeable cation. The smectite of these soils is nontronite when plagioclase is absent from the rocks; if there is plagioclase, intermediate terms in a series between aluminous nontronite and ferric montmorilonite, or a mixture of both, will occur.

The geochemical evolution is characterized by the loss ofsoluble elements and the fixing of the residual ones. As a function of the lost amount, calculated through the proportions in the different facies of the residual solid phase, the elements show the following mobility scale:

Mg > Ca > (Na, K) > Si > (Cu, Cr, Ni, Co, V, Mn, Fe) > (Al, Ti, Zr)

The majority of the residual elements are concentrated at the foothills and lower plain surfaces by the colluvial migration of the larger particles (oölites, residual minerals). Some elements are concentrated at the flat­lying surfaces, when the soil is deep, by adsorption onto clay minerals or into organic compounds. Thus, special care must be taken so that prospection work in soils does not lead to erroneous results.

The water of the sources in the ultrabasic areas is magnesian and bicarbonated, with considerable proportions of Si, Na and K. The composition of this water is in agreement with the loss of elements observed in the residual solid phase. However, the mobility of Ca, Na and K is exaggerated, because they are mainly contained in the silicates that weather in the saprolite facies.

The kind of weathering, indicated by the composition of the groundwater, is in agreement with the mineralogical products. This kind of weathering can be called ferrisilicification and it may be associated with some ferruginization periods.

The physico­chemical study confirms the tendency to the hydrolisis of the silicates, except for chlorite, that can be a supergene product. This study also shows that groundwater is in equilibrium with the aluminous nontronite, what explains the formation and the preservation of this mineral, and also confirms the absence of silicifications under the present conditions.

A BIOGEOQUÍMICA NA PROSPECÇÃO MINERAL. APLICAÇÃO DO MÉTODO EM ÁREA MINERALIZADA A COBRE NO RIO GRANDE DO SUL

BIOGEOCHEMISTRY IN MINERAL PROSPECTION. THE APPLICATION OF THE METHOD TO A COPPER­MINERALIZED AREA IN RIO GRANDE DO SUL

Maria do Carmo Lima e Cunha (1982)

Adviser: Milton Luiz Laquintinie Formoso

Abstract

The results of the application of biogeochemical prospecting are presented and discussed. The studied area, Santa Ivone Farm, Bagé, Rio Grande do Sul, is constituted of sedimentites and migmatites cut by pyrite, chalcopyrite, galena, and silver­bearing quartz veins. The native species Schinus lentiscifolius and Schinus dependens (regionally known as "aroeiras") were analyzed for Cu, Ni, V, Cr, Co, Pb and Zr through optical spectrography of ashes from leaves and twigs.

The data were statistically treated in order to determine background and threshold values. The plant density of occurrence, distribution and mechanisms of mineral constituents absorption from the soil are discussed for deduction of the possible relatioships between element concentration in the soil and in the plants.

The biogeochemical results indicate that, particularly for copper, there is a strong dependency of the data on the sampled species and organs, leading to the choice of S. lentiscifolius leaves as the most representative sampling media.

It is suggested that S. lentiscifolius is tolerant to high, though limited, copper concentration in the soils of the studied area. The correlation between the copper content in soil and in plant is found to be significant only when anomalous soils occur, indicating that the element absorption by the plant increases with the element concentration in solutions within the soils.

The author concludes that the biogeochemical method is efficient even in detailed work and in subtropical areas, where erosive agents normally remove the alteration cover. As compared to soil geochemistry, biogeochemistry also reveals the position of subsurface mineralization, and as a result of vertical and lateral extent of the plant radicular system, biogeochemical prospecting expands the volume meaning of each sample, resulting more representative, particularly where soils are less developed and/or transported.

PETROLOGIA E GEOQUÍMICA DO VULCANISMO ÁCIDO MESOZÓICO DA PROVÍNCIA MERIDIONAL DA BACIA DO PARANÁ

PETROLOGY AND GEOCHEMISTRY OF THE MESOZOIC ACIDIC VOLCANISM IN THE SOUTHERN PROVINCE OF PARANÁ BASIN

Ari Roisenberg (1989)

Adviser: grau obtido diretamente por defesa de tese

Abstract

The Mesozoic acidic volcanism of the southern Paraná Basin covers an area of about 45,000 km² and has a minimum volume of 8,900 km³. The field and petrographic studies have demonstrated that the acidic units probably represent a thick ignimbrite sequence with many pyroclastic features. The K­Ar dating indicates that the acidic volcanics are younger than 130 My. and present a contemporaneity with the latest basic flows. The results do not show clearly, as expected, a migration of the magmatic activity through the Paraná Basin and the basic volcanism was widespread in all directions at 150 My. Statistic studies on the geochemical data discriminate two main acidic rock­types, which correspond to the end­members of acontinuous scale between dacites and rhyolites, enriched in potassium. The magmatic modeling gives evidence that the generation of acidic liquids does not involve crystal fractionation and crustal assimilation from the associated basalts. Partial melting (19 to 23% of melting degree) of crustal sources with a composition equivalent to the bulk crust average is consistent in terms of major and trace elements. Simple mixing between the acidic end­members can explain the compositional variability. It is stressed that the heat emanated from basic intrusions combined with regional heating are responsible by the melting of crustal material and can create a limited miscibility with the basalts.

METALOGÊNESE DO OURO DA MINA DE BOSSOROCA, SÃO SEPÉ - RS

METALOGENESIS OF THE BOSSOROCA MINE GOLD, SÃO SEPÉ, RS

Jair Carlos Koppe (1990)

Adviser: Léo Afrâneo Hartmann

Abstract

The Bossoroca Mine gold deposit is a small epigenetic hydrothermal load with medium to relatively high gold contents of approximately 15 g/t. The ore is hosted by volcaniclastic rocks metamorphosed in the greenschist facies. Their age is Upper Proterozoic and they belong to the Campestre Sequence of the Bossoroca Complex.

The Bossoroca Complex comprises two sequences: one contains mafic­ultramafic rocks, essentially volcanic in origin, with komatiitic and tholeiitic composition, associated with rocks of chemical deposition (cherts and iron formations), designated the Arroio Lajeadinho Sequence. The other, named Campestre Sequence, is composed of calc­alkaline rhyolitic to andesitic­basaltic volcaniclastic rocks, associated with chemical sedimentary rocks (cherts and iron formations) and epiclastic rocks. This supracrustal sequence was submitted to greenschist and amphibolite facies metamorphism and to one major deformational episode.

The gold deposit is cnclosed in metamorphosed crystal and fine­ ­grained tuffs without any apparent lithological control. The deposit comprises essentially extension veins or specifically oblique­type shear veins. These veins were formed during phases of brittle and brittle­ductile deformation under conditions of simple shear.

The gold occurs preferentially from among crystals of quartz, calcite or sulfides, either filling fractures or not, and also secondarily as inclusions or as part of the structure of pyrite.

The composition of the mineralizing fluid was characterized through fluid inclusion studies and was essentially represented by the system H2O­CO2 with low salinity (= 1%). The average density of the fluids is 0,82 g/cm³. The average temperature of gold deposition corresponding to the main stages of mineralization, was approximately 247°C. Lithostatic pressures, at the time of emplacement of the mineralizations, was estimated as 500 to 1,300 bars, corresponding to shallow depths of formation.

The isotopic values of Ù13C and Ù18O indicated the presence of homogeneous fluids, stable conditions of pressure and temperature and suggest a metamorphic origin for the fluids responsible for the mineralization.

Based on one of the models presented, the fluids were generated by the granulitization of the lower crust, migrating along regional structures and reaching the upper crust to form the gold deposit. The origin of the gold could be either the lower or the upper crust, extractedfrom the rocks by the fluids generated during granulitization. The gold would have been transported in the form of thio­complexes and its deposition would be due to lowering temperatures, pressure and variation in Eh, pH or oxidation state of the fluid.

SULFETOS EM SEDIMENTOS DETRÍTICOS CAMBRIANOS DO RIO GRANDE DO SUL, BRASIL

SULFIDES IN CAMBRIAN DETRITIC SEDIMENTS OF RIO GRANDE DO SUL, BRAZIL

Marcelo José Ribeiro (1991)

Adviser: grau obtido diretamente por defesa de tese

Abstract

Two sedimentar deposits, both of them lodged into non­carbonated sediments, are analyzed in this thesis.

After a brief history on the development of the cupper element knowledge in Rio Grande do Sul State, a merely descritive part is showed, inclosing the geology from molassic sequences of the Sul­rio­grandense Shield (with emphasis on mineralized sediments), and the proper cupper and lead­zinc mineral-izations.

Connected to the anterior remarks, an interpretative part follows by analyzing these among others matters: the questions on the shallow geochemical effects of the mineralization, inverse zonallity in Minas do Camaquã deposit and the Cu­Pb­Zn­Ag zonallity in Santa Mariadeposit and native silver and silver (including their anomalous concen-trations). In addition, questions on the sulfides formation into the diagenetic evolutive frame of the sediments and the vein ore formation are also discussed.

At last, a general synthesis of the obtained knowledge is made. By using the Cu­Pb­Zn geological history and the comparative analysis on the sedimentar deposits of this elements, it is intended to place the studied deposits into a larger frame, by detaching the noted likeness and discrepances in relation to the usual world remarks. These deposits are also examined accordingly to a generic and foreseeing conceituation. Finally, a short review on the proper Guaritas basin research potential is made.

Petrologia das rochas vulcânicas e hipabissais da Associação Shoshonítica de Lavras do Sul - ASLS, RS

Evandro Fernandes de Lima

Lima,E.F., 1995. Tese (doutorado) - UFRGS de Pós-Graduação em Geociências,338 f.   Porto Alegre, RS, 1995.

  Abstract

The Lavras do Sul Shoshonitic Association (ASLS) is composed of effusive basic to intermediate rocks, pyroclastic deposits, hypabyssal monzonitic to rhyolitic bodies, spessartitic lamprophyres and granitic intrusive rocks. In this study, volcanic and hypabyssal rocks belonging to ASLS, exposed in the Lavras do Sul region, were investigated from a geological mapping, petrographic, mineral and lithochemical point of view, in order to elucidate their origin and evolution. They are stratigraphically positioned after calc-alkaline metagranitoids of Brasiliano age, and are succedded by a post-orogenic oversaturated alkaline magmatism. The alternate character of effusive and pyroclastic activity, the presence of columnar jointing in the effusive terms, and the lack of evidences for a subaqueous volcanic setting, indicates the cyclicity of the explosive-effusive aerial volcanic regime.  The lack of ductil deformation in the rocks of the ASLS in the Lavras do Sul region and their syn-transcurrence positioning in the Dom Feliciano Belt, suggest their late to post-orogenic character. The shoshonitic affinity, as well as the orogenic relationship of ASLS, is indicated by the SiO2-satured character of basaltic terms, as well as by their low-TiO2 content, relatively high amounts of Al2O3, Rb, Ba, Sr and LREE, K2O/Na2O ratio close to 1.0, and moderate HFS-element content. The crystallization of basalts was initiated with olivine, augite, labradorite and ilmenite, with pressures under 10 Kbar, from an evolved magma, as suggested by its low Ni, Cr, and Co contents and mg lower than 0.7.
REE petrogenetic modelling using the basaltic compositions point to primary liquids derived by  melting (F=5 to 10%) of a garnet lherzolitic mantle, enriched by a factor between 6 and 8, in REE and LIL elements. The intermediate volcanic rocks have augite, olivine and Ti-magnetite phenocrysts besides the dominant andesine-labradorite exhibiting a variation of habits ascribed to decompression. Petrogenetic modelling based upon major and trace-element data indicated that the intermediate liquids are probably derived from shoshonitic basalts through olivine+clynopiroxene fractionation. Some assimilation is evident from petrographic evidence, nevertheless its influence on magmatic differentiation is negligible.The intermediate liquids have probably evolved through plagioclase+augite±olivine fractionation up to monzonitic liquids, as indicated by mass balance and trace element modelling, as well as by the presence of cummulatic leucodioritic bodies. Volatile increasing fugacity during the fractionation process culminated with hornblende early stabilization in the monzonitic liquids. The fractionation of this phase together with plagioclase and biotite, leads to rhyolitic compositions similar to the granitic rocks of Lavras Granite Complex nucleous and of rhyolitic dikes belonging to the ASLS, as far as major and trace element, including REE are concerned. The late stages of shoshonitic magmatism are represented by intermediate to acid dykes and spessartitic lamprophyres. The higher amounts of MgO, alkalies, Cr, Ni, and lower of Al2O3, Sr, Zr and Nb observed in the lamprophyres are due to assimilation of calc-alkaline granitoids by volatile-enriched basic magmas of shoshonitic affinity.Isotopic Rb-Sr data obtained in the studied rocks yielded ages close to 653±23 Ma and initial ratios around 0.704. Similar values were determined in the nucleous of Lavras Granite Complex and in the Santo Antonio Monzogranite. As suggested by field relations, younger ages, close to those of alkaline magmatism, may be found by further geochronogical work. According to the data obtained in this study, the evolution of shoshonitic associations, similar to ASLS, may be explained by a model involving: fractionation of olivine and clinopyroxene from a mantellic primary basaltic magma, followed by fractionation of these phases and plagioclase, and eventually by plagioclase and hydrated mafic minerals. This evolution is illustrated in the QAP diagram by the trend parallel to AP for basic and intermediate terms, and then inflecting to quartz-rich liquids. The fractionation of iron-enriched mafic phases causes the Fe/Mg stabilization during the differentiation of shoshonitic magmatism.

INTEGRAÇÃO DE DADOS GEOLÓGICOS, DE SENSORIAMENTO REMOTO, ESPECTRORRADIOMÉTRICOS E GEOFÍSICOS APLICADA À PROSPECÇÃO DE DEPÓSITOS FILONEANOS DE FLUORITA HIDROTERMAL NO SUDESTE DE SANTA CATARINA

Tese de doutoramento, Curso de Pós-Graduação em Geociências, IGEO-UFRGS. Porto Alegre, 235 p.

Rosemary Hoff
rosehoff@pa.cprm.gov.br

Data da Defesa: 18/ 03 / 2002

Area de Concentracao: geoquímica

Orientador: Prof. Dr. Artur Cezar Bastos Neto

Banca Examinadores: Prof. Dr. Luis henrique Ronchi (UNISINOS) Prof. Dr. José Leonardo Silva Andriotti (CPRM) Prof. Dr. Nelson Amoretti Lisboa (UFRGS)

Palavras Chave: Integração de Dados; Sensoriamento Remoto Geológico; Geofísica Aplicada à Prospecção; Espectrorradiometria; Alteração Hidrotermal; Distrito Fluorítico de Santa Catarina.

RESUMO

Os processamentos de imagens orbitais efetuados através de técnicas de sensoriamento remoto geraram informações qualitativas de natureza textural (morfoestruturas). Estas permitiram (1) o reconhecimento de áreas com diferentes padrões estruturais tendo diferentes potencialidades para a prospecção de fluorita, (2) a identificação de novos lineamentos estruturais potencialmente favoráveis à mineralização e (3) evidenciaram prolongamentos extensos para as principais estruturas mineralizadas, (4) às quais associam-se um grande número de estruturas, antes desconhecidas, com grande potencial prospectivo. O aprimoramento de técnicas de classificação digital sobre produtos de razões de bandas e análise por componentes principais permitiu identificar a alteração hidrotermal associada às estruturas, incorporando novos critérios para a prospecção de fluorita. Buscando-se quantificar os dados de alteração hidrotermal, foi efetuada a análise espectrorradiométrica das rochas do distrito fluorítico. Integrando estas informações com dados TM LANDSAT 5, em nível de reflectância, obteve-se a classificação espectral das imagens orbitais, o que permitiu a identificação de estruturas menores com um detalhe nunca antes obtido. Os processamentos de dados aerogeofísicos forneceram resultados sobre estruturas (magnetometria) e corpos graníticos afetados por alteração hidrotermal (aerogamaespectrometria). Estes produtos foram integrados com dados TM LANDSAT 5 associando o atributo textural da imagem orbital ao comportamento radiométrico das rochas. Diagnosticou-se o lineamento Grão-Pará como o principal prospecto do distrito. E levantou-se uma série de dados sobre a compartimentação tectônica da região, a zonação de fácies das rochas graníticas (rocha fonte do flúor) e as alterações hidrotermais associadas ao magmatismo granítico. Isto permitiu a compreensão da distribuição regional dos depósitos de fluorita, adicionando-se um novo critério à prospecção de fluorita, a relação espacial entre a mineralização e a rocha fonte de F. Esta última corresponde às fácies graníticas da borda do Maciço Pedras Grandes.

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Geological, remote sensing, spectrorradiometric and geophysical data integration applied for hydrothermal fluorite veins prospection in southeast Santa Catarina State, Brazil.

KeyWords: data integrated; geological remote sensing; prospecting mining applied geophisic; spectrorradiometry; hydrothermal alteration; Mining Fluorine District of Santa Catarina

Abstract

Digital image processing in orbital images by remote sensing techniques generated qualitative textural information (morfo-structures). These allowed (1) the recognition of areas in different structural patterns with different fluorite search potentialities, (2) identification new structures potentially fluor-bearing and (3) evidence of extensive increase from the principal mineralized structures, (4) It’s associated a great number of structures, before ignored, that have great prospective potential. The accuracy of techniques of digital classification on products of ratio analysis by principal components showed the alteration associated to the structures, incorporating new criteria for the fluorite search. Searching for quantify the alteration, the spectral analysis of the rocks in fluor district was employed. Integrating reflectance information with TM LANDSAT 5 data, obtained the classification of the orbital images, identifying smaller structures in detai l. Geophysical data processing supplied results on structures (magnetometric) and granites alteration affected (aerogamaspectrometric). These products were integrated with TM LANDSAT 5 data, associating textural attribute in orbital image to radiometric behavior of the rocks. The Grão-Pará lineament was diagnosed as the principal into district. Tectonic blocking data, facies zonation in granites (F source rock) and alteration associated to the granite magmatism. This allowed to understanding regional distribution of the fluorite deposits, and defined new criteria to fluorite prospecting, spatial relationship by mineralization and rock source of fluor. This one is the external granitic facies of Pedras Grandes Massif.

PhD T H E S E S - PALEONTOLOGY:

OSTRACODES CENOZÓICOS DA AMAZÔNIA OCIDENTAL

CENOZOIC OSTRACODA OF THE OCCIDENTAL AMAZONIA

Ivone Purper (1977)

Adviser: Irajá Damiani Pinto

Abstract

The present thesis consists of a study on the Cenozoic Ostracoda of the Occidental Amazonia based on three drill cores and one outcrop.

Six new genera and nine new species are described and their significance to paleoecology and stratigraphy discussed. Nearly all the ostracodes studied were new forms, thus confirming previous studies based on mollusks suggesting the fauna to be endemic. Thanatocoenosis has taken place, as evidenced by the presence of reworked material consisting of typically brackishwaterostracodes associated with freshwater forms as well as by the associated presence of Mesozoic and Cenozoic forms. The latter are represented by genera such as Bisulcocypris and Cypridea, Upper Jurassic to Lower Cretaceous forms, together with Cenozoic ostracodes, among which there are some forms probably belonging to an age as late as Pliocene.

The name Pebas Formation is maintained instead of Solimões, even for those beds in the Brazilian side.

FORAMINÍFEROS DOS SEDIMENTOS SUPERFICIAIS E SUB­SUPERFICIAIS (PLIO/HOLOCENO) DA MARGEM CONTINENTAL DO MARANHÃO

FORAMINIFERA FROM THE SUPERFICIAL AND SUB­SUPERFICIAL SEDIMENTS (PLIO­HOLOCENE) OF THE CONTINENTAL MARGIN OF MARANHÃO STATE

Altair de Jesus Machado (1981)

Adviser: Ivan de Medeiros Tinoco

Abstract

One hundred eight species of foraminifera were identified in thirty five samples of superficial bottom sediments and in fourty five samples from two cores collected between Salinópolis and the Piauí/Ceará border, on the North­Northeastern Brazilian Continental Margins. Out of one hundred eight species, twenty three are of planktonic forms.

These sediment samples and cores were obtained during two oceanographic cruises: the "Geomar VIII", which sampled the continental shelf and the continental slope and the "North­Northeastern I", which was restricted to the continental shelf areas.

Studies on samples from core G­008 gave a biostratigraphic zonation with 40cm representing the Holocene deposition, 660cm representing Wisconsian sediments and 20cm representing the X zone, based on the characteristics of the planktonic forms Globorotalia menardii s.l. and Pulleniatia obliqueloculata.

Seven shelf sedimentary facies were distinguished.

The rate of the Holocene sedimentation on the G­008 core in water depth of 2,216m is of 3.6cm/1,000 years and the rate of the Wisconsian sedimentation is of 16.5cm/1,000 years.

OS OSTRACODES E SEU SIGNIFICADO NA INTERPRETAÇÃO DOS EVENTOS CENOZÓICOS NA BACIA DE PELOTAS - TRANSGRESSÕES, REGRESSÕES, PALEOECOLOGIA E BIOESTRATIGRAFIA

OSTRACODA AND THEIR MEANING FOR THE INTERPRETATION OF CENOZOIC EVENTS IN THE PELOTAS BASIN, RS - TRANSGRESSIONS, REGRESSIONS, PALAEOECOLOGY AND BIOSTRATIGRAPHY

Lília Pinto de Ornellas (1981)

Adviser: Irajá Damiani Pinto

Abstract

The present thesis consists of the systematic and paleoecological study of the Post­Miocene ostracodes from seven drillings of Petróleo Brasileiro S.A. (Petrobrás) from the Pelotas Basin, RS, Brazil.

Seventeen genera have been identified and systematically described, presenting a total of twenty­six species, being two new genera and eighteen new species.

The analysis of this faunula provided paleoecological data permitting to recognize and correlate the paleoenvironment of seven intervals, through different associations of ostracodes. It also permitted to determine several fluctuations of the sea level that could have occurred through the Upper Cenozoic as well as to establish four zones: Bradleya delicatula, Cyprideis posteroinflata, Coquimba atlantica and Argenticytheretta levipunctata.

ESTUDO DO MATERIAL DE PAREIASAUROIDEA (REPTILIA, ANAPSIDA, COTYLOSAURIA, PROCOLOPHONIA) DO NEOPERMIANO DO ESTADO DO RIO GRANDE DO SUL, BRASIL

STUDY OF THE PAREIASAUROIDEA MATERIAL (REPTILIA, ANAPSIDA, COTYLOSAURIA, PROCOLOPHONIA) FROM THE LATE PERMIAN OF RIO GRANDE DO SUL STATE, BRAZIL

Dina Celeste Fernandes Araújo (1982)

Adviser: Carlos de Paula Couto

Orientador Substituto: José Fernando Bonaparte

Abstract

This thesis deals mainly with the osteological description of cranial and postcranial materials of a new species of Pareiasaudoidea, Pareiasaurus americanus n. sp.

These materials were collected in outcrops (km 204 and km 204+600m) along the Bagé­Aceguá Highway (BR­153), Rio Grande do Sul State, Brazil, made up of sediments belonging to the upper Armada facies of the Estrada Nova Formation, as defined by Figueiredo Fº (1972).

Skull, scapula­coracoid and right humerus (km 204 outcrop) were designated as the holotype of the new species; associated with a pelvis of a young specimen of the same outcrop, plus postcranial materials (an almost complete axial skeleton, pelvis, dermal scutes and segments of the right anterior and posterior limbs) of the km 204+600m outcrop, it cons-titutes the hypodigm.

The osteological study of the material reveals that P. americanus presents clear affinities with the forms occurring in the Daptocephalus Zone of the Lower Beaufort Series, Karroo System, Africa. In terms of chronocorrelation, this suggests that the relationships of the Armada facies with the Estrada Nova Formation should be revised.

Paleobiogeographical considerations are also presented in this study. Dispersal routes are discussed, particularly the ones in reference to the paleotetrapods of the Paraná and Karroo Basins during the Permian.

A new schema for the phylo-genetic derivation of the pareiasaurs is here presented. It differs in some aspects from Boonstra's (1932c) approach to the subject. As a result of this new schema, an alternative taxonomic arrangement is also proposed for this group of fossil reptiles.

OSTEOLOGIA DO ESQUELETO APENDICULAR DOS LAGARTOS MACROTEIÍDEOS (SAURIA, SCINCOMORPHA, TEIIDAE)

OSTEOLOGY OF THE APPENDICULAR SKELETON OF THE MACROTEIID LIZARDS (SAURIA, SCINCOMORPHA, TEIIDAE)

Lígia Krause (1983)

Adviser: Mario C. Barberena

Associated Adviser: Norma Maria Baptista Gomes

Abstract

A comparative osteological account on the appendicular skeleton of the macroteiid lizards (Ameiva, Callopistes, Cnemidophorus, Crocodilurus, Dicrodon, Dracaena, Kentropyx, Teius and Tupinambis) is presented here.

Structural modifications, as shown by the osteological study, are comparatively analyzed according to their functional implications, particularly in reference to the locomotor habitus.

Osteological study of the scapula did not show the presence of a true fenestra. However, the fenestral area is indicated by a thinner ossification. More significant modifications were observed in the foot of the macroteiids and can be functionally related to the locomotion in different environments.

Intramembral and limb­trunk ratios indicate slow to vary fast quadrupedal walking habitus. Bipedalism, however, can eventually occur associated with high speed.

A brief review of the pa-leontologic record of saurians is presented, allowing some inferences on their dispersal routes, as compared to the present geographic distribution.

PALEOECOLOGIA E BIOESTRATIGRAFIA (FORAMINIFERIDA) DA FORMAÇÃO PIRABAS, ESTADO DO PARÁ

PALAEOECOLOGY AND BIOSTRATIGRAPHY (FORAMINIFERIDA) OF THE PIRABAS FORMATION, PARÁ STATE

Jane Maria Garrafielo Fernandes Martins (1984)

Adviser: Irajá Damiani Pinto

Associated Adviser: Alwine Bertels

Abstract

The present thesis studies the benthonic and planktonic foraminifera from the Miocene Pirabas Formation (Maury, 1925). The study was based on four drilling cores made in northeastern Pará State, Brazil.

Eighty seven taxa are identified and described.

Paleoecologic parameters related to the faunistic trend and the taxonomic composition allowed the characterization of the paleoenvironment as shallow marine and of normal salinity.

The individual analysis of each drilling core, taking into account the generic composition and the diversity of foraminifera, showed alterations in the faunistic assemblage probably due to small fluctuations of the sea level.

From the base to the top of the C­9 drill, three biofacies were individualized, related to shelf, marginal marine and shelf environments,respectively. In the AB­2 drill, two biofacies were recognized. The base was attributed to a shelf environment and the top to a marginal marine one. In the SB­1 drill, from the base to the top, three biofacies were characterized corresponding to shelf, marginal marine and shelf environments.

Based on the planktonic assemblage, the deposition of Pirabas Formation was attributed to Early Miocene, and correlated to the bioestratigraphic N4 Zone of Blow (1969) and the Globorotalia kugleri Zone proposed for the Brazilian Continental Shelf.

Younger Miocene strata were detected and correlated to the N5 Zone of Blow (op. cit.), according to the presence of Globigeniroides quadrilobatus altiaperturus Bolli.

Several taxa cited and described originally for the Pirabas Formation are here summarized.

PALINOLOGIA DE SEDIMENTOS QUATERNÁRIOS DO CONE DE RIO GRANDE, BRASIL

PALYNOLOGY OF QUATERNARY SEDIMENTS FROM THE RIO GRANDE CONE, BRAZIL

Maria Luísa Lorscheitter (1984)

Adviser: Irajá Damiani Pinto

Associated Adviser: Edgardo Juan Romero

Abstract

A palynological analysis of a South Atlantic sedimentary core, situated in the Continental Rise of Rio Grande do Sul, Brazil, in the latitude 33°33'S and longitude 48°28'W was accomplished. This core (T15), 7.50m long, was collected at a 3,200m depth of the water lamina, in the Rio Grande Cone area, during the GEOMAR VII mission. This mission was carried out by the Navy Geology and Geophysics Program (Board of Hydrography and Navigation of the Navy Ministry).

It was made a qualitative and quantitative analysis of the pollinic material contained in 19 samples, collected from the bottom to the top of the core.

The research was divided into two parts. The first one involved a taxonomic study of the pollinic content. The second one was an analysis of the sea level oscillations, lacustrine conditions and floristic changesin the adjoining Coastal Plain, as well as a paleoambiental and paleoclimatic evaluation.

In the taxonomic section 80 pollinic components, found in the various samples, were described and illustrated: fungi (3), chlorophytes (3), pirhophytes (2); histrichospherids (2), bryophytes (2), pteridophytes (14), gymnosperms (4), angyosperms (50), besides scolecodonts, foraminifera resistant to the chemical treatment, and undetermined fragments of vegetal tissue.

Sea level oscillations were initially detected through percentual relations between marine organisms and pollen and spores. CaCO3 variations were employed as an additional datum. Thus, the Early Würm, the Würmian Interstadial, the Late Würm and the Holocene were made clear.

Subsequently, an analysis of the Coastal Plain lacustrine conditions, by means of the relations between the pollen and spores of terricolous vegetals, and of fresh water elements was developed. The results provided evidences of humid and dry etapes.

Finally, floristic changes through the percentual relations among the different pollinic elements of the adjoining continental flora were studied. The changes displayed by the sea level oscillations, by the flora and the different lacustrine conditions in the distinct phases of the Glacial Würm and of the Holocene, served as the basis for paleoenvironmental interpretations.

Based on this information, a paleoclimatic reconstruction of Rio Grande do Sul Coastal Plain and probably of Uruguay and also Buenos Aires Province (Argentina), during the last Pleistocene glacial stage was tried.

OSTRACODES DO SISTEMA LAGUNAR DE TRAMANDAÍ, RS, BRASIL. SISTEMÁTICA, ECOLOGIA E SUBSÍDIOS À PALEOECOLOGIA

OSTRACODA OF THE TRAMANDAÍ LAGOONAL SYSTEM, RS, BRAZIL. SYSTEMATICS, ECOLOGY AND PALAEOECOLOGICAL SUBSIDIES

Norma Luiza Würdig (1984)

Adviser: Irajá Damiani Pinto

Abstract

Twenty­seven species of ostracodes, including two new genera and five new species are described from the Lagoonal System of Tramandaí, in the State of Rio Grande do Sul, Brazil.

Ecological data on the lakes and lagoons, such as physico­chemical parameters, morphometric characteristics, vegetal communities and factorswhich control their dynamics are presented.

The overall influence of the data on the distribution and abundance of the ostracode fauna is discussed.

Results of laboratory tests of ostracode tolerance to salinity and conductivity are presented.

REVISÃO DOS TRILOBITAS CALMONIÍDEOS E COMUNIDADES FAUNÍSTICAS DA FORMAÇÃO PONTA GROSSA, DEVONIANO, NO ESTADO DO PARANÁ

REVISION OF THE CALMONIID TRILOBITES AND THE FAUNISTIC COMMUNITIES OF PONTA GROSSA FORMATION, DEVONIAN OF PARANÁ BASIN

Marlene Terezinha Barcellos Popp (1985)

Adviser: Irajá Damiani Pinto

Associated Adviser: Bruno Alberto Baldis

Abstract

The distribution of Devonian trilobites along the Ponta Grossa Formation in the State of Paraná as well as their relations to other South America faunas are the main concern of this thesis.

The recognition of the Malvinocafrica Province in South Africa and in the Malvinas Islands is also established, together with the suggestion for a Brazilian Province or a Paraná Subprovince and also for an Amazonian Province or Subprovince.

For this aim, studies were performed concerning the revision of trilobites described and determined by Clarke (1913), such as: Calmonia signifer, C. subseciva, Pennaia pauliana and Metacryphaeus australis. Some new forms are herein described, as follows: Calmonia paranaensis n.sp., Jaguaraivaspis salamunii n.g., n.sp., Metacryphaeus sedori n.sp., M. granulata n.sp. and Parabainella brasiliensis n.g., n.sp., all of them belonging to the subfamily Calmoniinae.

For the first time, mention is made about the subfamily Acastavinae, represented by Brunaspis sandominguensis n.g., n.sp., as well as to the subfamily Acastinae, represented by Paranacaste pontagrossensis n.g., n.sp.

It was also possible to perform an analysis on the paleoenvironmental variation of the Ponta Grossa Formation, based on the recognition of Brachiopoda and associated lithologies.

A transgressive­regressive cycle is identified with the maximum transgression corresponding to the Tibagi Member, which allows twice the record of the same paleoecological conditions: the first one in the Jaguariaíva Member, and the second in the São Domingos Member.

FORAMINÍFEROS DA MARGEM CONTINENTAL BRASILEIRA. FOZ DO RIO AMAZONAS AO CABO ORANGE. TAXONOMIA, ECOLOGIA E FACIOLOGIA

FORAMINIFERA FROM THE BRAZILIAN CONTINENTAL MARGIN, FROM THE MOUTH OF AMAZONAS RIVER TO ORANGE CAPE. TAXONOMY, ECOLOGY AND FACIOLOGY

Itamar Ivo Leipnitz (1987)

Adviser: Jorge Alberto Villwock

Associated Adviser: Ivan de Medeiros Tinoco

Abstract

The present study deals with planktonic and benthonic foraminiferal fauna obtained from recent sediments of the Northern Brazilian Margin, between the mouth of the Amazon River and the Orange Cape, by means of the Oceanographic Operation Geomar II and III.

Two methods were used to characterize the fauna: the Drooger & Kaaschieter and Schott. A supplementary methodology, here characterized as "Special Fauna", was applyed to both Geomar Operations; it is a selective process by which specimens larger than 2mm are picked up from the sediments for studies of benthic biology.

Two hundred taxa were identified; 16 planktonic and 184 benthonic, forming 94 genera and 12 superfamilies. Through a quali­ ­quantitative analysis it was possible to observe that in the substract of the Amazonic Facies there is a fauna of restrict species. As the substract is being enriched by sand, there is an increase in the number of taxa. In the sediments of the Sandy Facies there is a fauna rich in species.

The presence of encrusting taxa in this substract contradicts the idea of the existence of a movable substract and suggests its characterization as a relict sand. In the substract of the Biodetrital Facies the fauna is quali­quantitatively rich enough. In the substract of the Slope Facies it was observed a great number of planktonic forms, the benthonic assemblage being dominated by 4 species.

From the benthonic assemblage only Amphistegina lessonii D'Orbigny, 1826 and Spiroplectammina floridana (Cushman), 1922 were constantly present in the sediments; other 14 species were additional and the reming 168 occasional.

The constant presence of Amphistegina lessonii D'Orbigny, 1826 and Spiroplectammina floridana (Cushman), 1922 and the disappearance of Archaias angulatus (Fichtel et Moll), 1778 and Peneroplis spp. suggest that the Subprovince of Northeastern Brazil admits two distinct areas.

Taking into consideration the two methods above mentioned, the values found for determining frequency, constancy, dominance, abundance and specific diversity are the same. It is suggested, however, the use of additional data concerning the benthonic population.

PALEONTOLOGIA DOS BRACHIOPODA - LINGULIDA, STROPHOMENIDA, SPIRIFERIDA, TEREBRATULIDA - DEVONIANOS DA SERRA DE ATIMÃ E ARREDORES, MATO GROSSO, BRASIL

PALEONTOLOGY OF THE LINGULIDA, STROPHOMENIDA, SPIRIFERIDA AND TEREBRATULIDA DEVONIAN BRACHIOPODS FROM SERRA DE ATIMÃ AND ITS SURROUNDINGS, MATO GROSSO, BRAZIL

Raquel Quadros (1987)

Adviser: Irajá Damiani Pinto

Associated Adviser: Francisco Eudoro Nullo

Abstract

The outcrops of the Devonian sequence in the Atimã mountain and adjacent area in Chapada dos Guimarães municipality, State of Mato Grosso, Brazil, comprise the Furnas and Ponta Grossa Formations. The base and the top are characterized by a local unconformity. In this area five new outcrops were discovered; the fossiliferous levels of these outcrops are situated mostly at the base of the Ponta Grossa Formation.

A found fossil fauna comprises brachiopods, pelecypods, gastropods, tentaculits, trilobites, fragments of echinoderms and fossils traces; there is a predominance of brachiopods represented by Lingulida, Strophomenida, Spiriferida and Terebratulida making a total number of twelve genera, ten species and two forms with no denomination.

From the total fauna of brachiopods, Craniops trombetana (Clarke, 1889), Australostrophia mesembria (Clarke, 1913), Notiochonetes falklandica (Morris e Scharpe, 1846), Coelospira sp. Hall, 1894, Australospirifer iheringi (Kayser, 1900), Derbyina whitiorum Clarke, 1913, Podolela sp. Kozlowski, 1929 e Schuchertella sp. are registered for the first time in the State of Mato Grosso. One emend for the genus Derbyina is proposed; a new species of Chonostrophiidae is described for the Ponta Grossa Formation, Chonostrophia andina.

Most of these taxa include specimens of strongly malvinocafric characteristics, so that the study of brachiopods permitted to re­established that faunistic affinity.

An older age for these Devonian deposits with a macrofauna of invertebrates is suggested for the first time. The fauna of brachiopods indicates a Late Siegenian - Early Emsian stage.

PALEOPATOLOGIA COMPARADA DE VERTEBRADOS. O HOMEM DE LAGOA SANTA, O HOMEM DO SAMBAQUI DE CABEÇUDA E MAMÍFEROS PLEISTOCÊNICOS

VERTEBRATE COMPARATIVE PALAEOPATHOLOGY. LAGOA SANTA MAN, CABEÇUDA SAMBAQUI MAN AND PLEISTOCENE MAMMALS

Jorge Ferigolo (1987)

Adviser: Mario C. Barberena

Abstract

This thesis comprehends a proposal for a new comparative and interdisciplinary approach on Palaeopathology. Pathologies present in Man and in Pleistocenic mammals of the Orders Edentata, Notoungulata, Litopterna and Artiodactyla are comparatively described and discussed. The diseases detected were: dentary, mainly periapical lesions related to the exposition of the pulpar cavity; degenerative ones, like osteoarthritis; nutritionary, represented by the Park­Harris lines; traumatic and neoformations (external auditory canal "osteomas"). Vertebral column alterations related to the neotenic characters of Man and other mammals were also detected. For some alterations such as intervertebral osteophytes and bridges a new interpretation in adaptative terms is suggested, in contradistinction to the usual ones. In the comparisons between the two human populations (Lagoa Santa Man, and Sambaqui de Cabeçuda Man), some significant differences were found, such as those in the nutritionary, neoformative and osteoarthritic diseases. The nutritionary differences are related to better nutritionary conditions in the Sambaqui de Cabeçuda Man, a coastal population. The other differences were probably related to life conditions and habits. Whereas in the human material the old age manifestations prevailed along with a great number of dental lesions, osteo­arthritis largely predominated in the palaeomastozoological material. In this material dental pathologies were very rare, except for the enamel hypoplasias found in the toxodontids (Order Notoungulata). Some diseases were described for the first time for a palaeomastozoological material, as for example the Scheuermann Disease, the "Schmorl hernia", osteochondritis dissecans, and the enamel hypoplasias. Anomalies and infections were very rare in the total material examined. It is proposed in this work to deepen the palaeopathological studies to avoid mistakes in Palaeontology, and to obtain a better understanding concerning some life habits. At the same time, Comparative Anatomy, Evolutionary Theories and Comparative Palaeopathology should be brought nearer for a better understanding of the lesions nature.

DIATOMÁCEAS DA TURFEIRA DE ÁGUAS CLARAS, PLANÍCIE COSTEIRA DO RIO GRANDE DO SUL: TAXONOMIA, ASPECTOS ECOLÓGICOS E SUBSÍDIOS À PALEOLIMNOLOGIA

DIATOMACEAE FROM THE ÁGUAS CLARAS PEAT, COASTAL PLAIN OF RIO GRANDE DO SUL: TAXONOMY, ECOLOGICAL ASPECTS AND PALAEOLIMNOLOGICAL SUBSIDIES

Vera Lúcia Maróstica Callegaro (1988)

Adviser: Yvonne T. Sanguinetti

Associated Adviser: Hermes Moreira Filho

Abstract

This thesis aims at examining the diatom flora from Águas Claras peat, located in the Coastal Plain of the State of Rio Grande do Sul.

The study of the horizontal distribution was based on the analysis of surface samples from six points along the bog. The vertical distribution resulted from the analysis of 20 samples from a continuous one­meter­deep profile comprising the peat layer.

A total number of 54 specific and infra­specific taxa resulted from this study; these taxa are grouped in 5 families and 11 genera. Naviculaceae accounted for 54.5% of the genera listed. The genera with the highest number of species and varieties were Eunotia and Pinnularia. Eleven of the identified taxa are new citations for the State of Rio Grande do Sul.

The analysis of the information content (I) showed two associations in the superficial layers: A1 and A2. The Jaccard index indicated 33.7% similarity among the species of the A1, and 27.8% of the A2 association points. The ecological preferences of the abounding species in A1 and A2 associations characterize the existence of a lentic, oligohaline, acid and oligotrophic environment. The separation of A1 and A2 groups seems to be influenced by pH fluctuations in the environment, probably due to the lateral variations of the vegetable distribution.

The qualitative and quantitative analysis of the diatoms present in the sedimentary sequence studied showed some association alterations from the bottom to the top. The evolution of the sedimentation environment was evidenced in the frequence variations of Eunotia lineolata Hustedt var. lineolata: the higher frequency values pertain to shallower water, lower pH and higher temperature.

The ecological conditions recorded in the study of diatoms in Águas Claras suggest regional climatic variations with some water level fluctuations; they also show a typical lentic, acid, fresh water environment in accordance with the genesis of the peat.

PALINOLOGIA, BIOESTRATIGRAFIA E PALEOECOLOGIA DO NEOPALEOZÓICO DA BACIA DO PARANÁ NOS ESTADOS DO RIO GRANDE DO SUL E SANTA CATARINA, BRASIL

LATE PALEOZOIC PALYNOLOGY, BIOSTRATIGRAPHY AND PALAEOECOLOGY OF THE PARANÁ BASIN IN RIO GRANDE DO SUL AND SANTA CATARINA STATES, BRAZIL

Marleni Marques Toigo (1988)

Adviser: grau obtido diretamente por defesa de tese

Abstract

In the present thesis the microflora contained in the Late Paleozoic sediments from the Paraná Basin is described and analyzed. The Sporopollinic associations obtained from drill samples and from outcrops of the main coalfields in the State of Rio Grande do Sul and southern part of Santa Catarina State were identified.

The sedimentary sequence taken into consideration comprises the following lithostratigraphic units: Itararé Group, Guatá Group (Rio Bonito and Palermo Formations) and Passa Dois Group (Irati Formation).

The palynological content here studied is represented by Triletes and Monoletes spores, related to PTERIDOPHYTA, Monosaccites, Disaccites and Striatiti pollen grains belonging to GYMNOSPERMAE, besides ALGAE (Botryococus braunii), Incertae sedis forms probably related to ALGAE and marine microfossils (ACRITARCHA).

Based on the vertical and lateral distributions of Monosaccites, Disaccites and Striatiti pollen grains and the relative abundance of the identified taxa, a biostratigraphic zonation is here proposed.

The palynobiostratigraphic system includes two Interval Zones, here denominated Cannanoropollis korbaensis Zone and Lueckisporites virrkkiae Zone. The former is subdivided into three Interval Subzones: Protohaploxypinus goraiensis, Caheniasaccites ovatus and Hamiapollenites karrooensis.

Previous papers on the palyno-stratigraphy of the Paraná Basin (Neopaleozoic) were taken into consideration to offer this new interpret-ation both of the biostratigraphy and paleoecology of this gondwanic sequence.

An age corresponding to the Early Permian (Sakmarian/Kungurian) to Late Permian (Kazanian/Tatarian) interval was attributed to the microflora, by comparison to other sporopollinic associations from the Paraná Basin as well as from other Gondwana regions.

Different types of paleoenvironments were identified: lacustrine, lacustrine/paludal and marine.

The paleoenvironments were determined by the analysis of the floristic associations, the relationship between the macro and microflora, the preferential habitats of the vegetation which originated the spores and pollen grains as well as of the presence of marine palaeo-microplankton.

PADRÕES EPIDÉRMICOS DA FLOR GLOSSOPTERIS NA JAZIDA DO FAXINAL (FORMAÇÃO RIO BONITO, KUNGURIANO, RS): IMPLICAÇÕES TAXONÔMICAS, BIOESTRATIGRÁFICAS, PALEOECOLÓGICAS E PALEOGEOGRÁFICAS

EPIDERMIC PATTERNS OF THE GLOSSOPTERIS FLORA IN THE FAXINAL COALFIELD (RIO BONITO FORMATION, KUNGURIAN, RS): TAXONOMICAL, BIOSTRATIGRAPHICAL, PALAEOECOLOGICAL AND PALAEOGEOGRAPHICAL IMPLICATIONS

Margot Guerra­Sommer (1988)

Adviser: grau obtido diretamente por defesa de tese

Abstract

This thesis presents an analysis of the oryctocenosis proceeding from "Tonstein" associated to a coal layer in Faxinal Coalfield (Rio Bonito Formation, State of Rio Grande do Sul, Brazil).

The taphocenosis, preserved as coalified compression, is primarily composed of foliar organs. There is a predominance of Glossopteridales corresponding to the species Glossopteris brasiliensis n. sp., Glossopteris similis­intermittens n. sp., Glossopteris papillosa n. sp., and Glossopteris rio­grandensis n.sp. There are very few isolated reproductive structures of the species Plumsteadia sennes Rigby and seeds described as Platycardia sp. Leaves of Cordaitanthales are very important elements, belonging to a single species, Rufloria gondwanensis n. sp. Fragments of sterile fronds, characterized as PTERIDOPHYLLA (sensu Boureau & Doubinger, 1975), corresponding exclusively to Sphenopteridales (Sphenopteris cf. Sph. ischanovensis, Sphenopteris sp.), are very seldom represented.

As a result of numerical taxonomy, the possibility of the existence of two large groupings for the Glossopteridales examined was assumed.

Geochemical analyses (Total Organic Carbon, Rockeval Pyrolysis, Organic Petrography, Soxllet Extraction, Liquid Chromatography, Gaseous Chromatrography of Paraffins, Esteranes and Trepanes, Carbon Isotopes) were made on the carbonified material originating from the Glossopteridales, for a preliminary geochemical characterization of the group.

Paleobotanic data indicate that the Rio Bonito Formation in Rio Grande do Sul seems to comprise different biostratigraphic intervals. The basal paleofloristic associations would have been deposited coetaneously with those of the Itararé Group and are compositionally very similar to the flora found in this unit. The depositional interval of these associations would correspond to the Artinskian. Yet the association found in the Faxinal Coalfield would have been deposited on a younger interval, corresponding to the Kungurian. The interval corresponding to the totality of the Rio Bonito Formation in Rio Grande do Sul would be Artinskian­Kungurian in age.

A likely correlation of the Taphoflora analyzed in this research with the Argentinean Glossopteris Zone (Sauce Grande and Islas Malvinas Basins) is indicated. However, the total content of the Rio Bonito Formation in Rio Grande do Sul also suggests significant correlations with the Gangamopteris Zone (Paganzo Basin). Safe correlations with taphofloras of other Gondwanic provinces cannot be established.

The evidence that the Cordaitanthales found in the association are related, because of their epidermic patterns, to Rufloria Meyen, the typical Angara form, led to some hypotheses. Migration is considered to be the most plausible reason for the presence of this form in the association. This hypothesis is supported by paleographic maps (Smith et al., 1981) which show, in the Permian, a continental alignment that would render migration possible.

Hypoautochthonous deposition in a body of very calm water derived from a mesophilous environment, cor-responding to forests developed in swamps, is assumed for the association. The sculpturing of the epidermic tissues, especially of the Glossopteridales, contrastively suggests adaptations to xeromorphic conditions which are different from the ones indicated by other parameters. Several causes are suggested for the evidences, based on studies on present day flora, mainly related to character-istics of soil composition, which can be responsible for xeromorphic features in plants.

The parameters obtained in the epidermic analysis associated with the compositional data on oryctocenosis and evidences of the relation plant­insect suggest a temperate paleoclimate with one mild cyclical period. The indication of the interaction plant­insect, given by the presence of damaged leaf margins, seems to suggest an already specialized feeding habit, herbivorous, for specific groups of insects in the Kungurian, and adaptation to weather severity, perhaps through diapause.

ASSEMBLÉIAS DE CONODONTES DO CARBONÍFERO DA BACIA DO PARANÁ

CARBONIFEROUS CONODONT ASSEMBLAGES OF THE PARANÁ BASIN

Valesca Brasil Lemos (1990)

Adviser: Ivone Purper

Abstract

Carboniferous samples from wells drilled in the Amazon Basin (Eastern Amazon region) and Solimões Basin (Western Amazon region), Brazil, were processed for conodont bioe-stratigraphic studies.

The depositional sequence begins at the base with a cross­bedded sandstone of the Monte Alegre Formation of fluvial­aeolian origin, with marine carbonates intercalated. A pronounced unconformity exists at the base of the Monte Alegre Formation which, in most of the area, was deposited over pre­Carboniferous sediments in general of Devonian age.

This formation is overlain conformably by the Itaituba Formation which consists of interbedded carbonates, evaporites and shales, grading upwards to the Nova Olinda Formation with similar composition, but predominantly evaporitic. Black shales are the result of maximum inundation of the basin duringthe cyclic transgressions and constitute excelent bed markers. Evaporites represent regressive events followed by dessication.

Conodont assemblage zones were established for the Carboniferous section.

The Neoghathodus symmetricus/ Rhachistognathus muricatus Zone (Morrowan in age) is referable to the Monte Alegre Formation and lower part of Itaituba Formation. The Diplognathodus orphanus/ Diplognathodus coloradoensis Zone, recorded in the middle and upper parts of Itaituba Formation, helps to date this zone as of Atokan age.

Sampling problems do not allow a reliable interpretation of Desmoinesian and Missourian intervals. A Strepto-gnathodus elongatus / Idiognathodus ellisoni Zone was recorded at the base of the Nova Olinda Formation.

PRESTOSUCHUS CHINIQUENSIS HUENE 1942 (REPTILIA, ARCHOSAURIA, THECODONTIA, PROTEROSUCHIA, RAUISUCHIDAE) DA FORMAÇÃO SANTA MARIA, TRIÁSSICO DO ESTADO DO RIO GRANDE DO SUL, BRASIL

PRESTOSUCHUS CHINIQUENSIS HUENE 1942 (REPTILIA, ARCHOSAURIA, THECODONTIA, PROTEROSUCHIA, RAUISUCHIDAE) FROM THE SANTA MARIA FORMATION, TRIASSIC OF RIO GRANDE DO SUL STATE, BRAZIL

Sérgio Alex Kugland de Azevedo (1991)

Adviser: Mário C. Barberena

Abstract

The cranial and partial postcranial osteology of Prestosuchus chiniquensis Huene 1942 is described here. The material was collected in sediments of the Santa Maria Formation (Ladinian of Rio Grande do Sul State, Brazil).

A carnivorous­predatory habitus for this species is clearly indicated by the morpho­functional characteristics of the masticatory apparatus.

From a paleoecological point of view, it can be said that Prestosuchus chiniquensis was the main occupant of the carnivorous­predatory niche during the Middle to Late Triassic transition.

This temporal transition also indicates the decline of the paleoecological role played by this huge thecodont, since sedimentary and some tectonic evidences point to a change to more drastic (drier climate) condictions in the paleoenvironment. New forms seem to have had better opportunities of survival in the Late Triassic paleoenvironment.

Thecodont taxonomy has been the subject of an extended discussion among the authors dealing with this group. As controversies still remain, and until they are clarified in face of more abundant materials, we decided, for the purposes of the present work, to follow the taxonomic proposition of Bonaparte (1982).

OS RINCOSAUROS SUL­AMERICANOS E SUAS RELAÇÕES COM OUTROS REPRESENTANTES DO GRUPO

THE SOUTH AMERICAN RHYNCHOSAURS AND THEIR RELATIONSHIPS TO OTHER REPRESENTATIVES OF THE GROUP

César Leandro Schultz (1991)

Adviser: Mário C. Barberena

Abstract

This thesis intends to present a review on the knowledge on fossil rhynchosaurs, particularly the South American forms. The parallel revision of the fossil materials and the papers written about them, on the light of today's concepts upon paleobio-geography, paleoclimatology and specially taphonomy (whose influence on the resultant morphology of the fossil bones is stressed), pointed to the necessity of changes in some of the ideas currently accepted. Among the fossil materials attributed to the genus Scaphonyx, the single only genus until now established to South America, some modifications in their taxonomic status are needed. Most of them belonged in reality to the genus Hyperodapedon. On the other hand, comparison between specimens of Scaphonyx fischeri and Scaphonyx sanjuanensis revealed a lack of diagnostic characters for justifying the existence of two species. Thus,the second must be considered a synonym of the first. By its side, the third species of the genus, Scaphonyx sulcognathus, presents morphological features that strongly indicate that it must be considered a new genus, which should belong to a subfamily different from the one to which Scaphonyx belongs. However, rhynchosaurian classification at sub-family level is not sufficiently clear today; therefore, propositions in this sense should be posponed for a while. The presence of the first pre­Carnian rhynchosaurian form ("Mariante Rhynchosaur") is also here reported and discussed. Several data obtained from the most recent collected South American rhynchosaurs, dealing with dentition, jaw mechanics and composition of paleofaunas, were integrated to discuss their implication on paleo-ecological and biostratigraphical interpretation.

PALINOLOGIA DO GRUPO ITARARÉ NO RIO GRANDE DO SUL

PALYNOLOGY OF THE ITARARÉ GROUP IN RIO GRANDE DO SUL

Maria Elice Rosa Dias (1993)

Adviser: Marleni Marques Toigo

Abstract

This thesis refers to a study of the microflora registered in samples of a sedimentary sequence correspondent to Itararé Group in Rio Grande do Sul State.

The qualitative and quantitative analysis of the microfloristic associations as well as the taxonomy of one hundred thirty three (133) taxa occurrent in the Herval, Dom Pedrito, São Sepé, São Gabriel, Cachoeira do Sul, Gravataí and Rio Pardo areas are presented.

The sporopollinic association identified is constituted of spores of PTERIDOPHYTA (FILICOPHYTA, LYCOPHYTA and rare SPHENOPHYTA), pollen grains of GYMNOSPERMAE (CONIFEROPHYTA, CORDAITOPHYTA and PTERIDOSPERMOPHYTA), ALGAE (Botryococcus and Tasmanites), ACRITARCHS and elements related to ALGAE (Portalites).

The interpretation in relation to the paleoclimate, paleoecology and also the paleogeographic reconstitution of some of the areas analyzed is made (Candiota and Leão­Capané mine regions).

The extension of the marine environment that existed during the deposition of this unity in the south of Paraná Basin is inferred through the register of the marine microfossils in several searched areas.

The age of these sediments correspond to Sakmarian/Artinskian (H2 to I1 intervals of Daemon & Quadros, 1970 and Cannanoropolis korbaensis Zone, as well as to Protohaploxypinus goraiensis and base of Caheniasaccites ovatus subzones of Marques­Toigo, 1988).

MOLUSCOS CENOZÓICOS DE SUB­SUPERFÍCIE EM IMARUÍ, SANTA CATARINA, BRASIL: PALEOECOLOGIA, TRANSGRESSÕES E REGRESSÕES

SUB­SUPERFICIAL CENOZOIC MOLLUSKS IN IMARUÍ, SANTA CATARINA, BRAZIL: PALAEOECOLOGY, TRANSGRESSIONS AND REGRESSIONS

Vera Lúcia Lopes Pitoni (1993)

Adviser: Ieda Regina Forti Esteves

Abstract

The taphocoenosis of mollusks is studied in the area around Imaruí lagoon, State of Santa Catarina, Brazil. It was obtained from data of drilling cores, with the purpose of characterizing the paleoenvironment and identifying records of Holocene fluctuations of the relative sea­level that occur along the coast of Brazil.

One hundred and nine strata of 15 drilling cores were analyzed by sorting, identifying, counting and characterizing the Mollusca taxa and the paleobiota that comes along. For the paleoecological study the follow-ing criteria were adopted: Index of Specific Diversity of Mollusks, Relative Abundance of the Counted Paleobiota, Dominant Mollusks, Preservation State of Dominant Mollusks, Present Habitat of the Paleobiota that comes along, Present Investigation of the Mollusks in Neighboring Areas, Identification of the Sedimentation Environment and Cluster Analysis.

Seventy­five Mollusca species were identified. At present, 63 of them occur in the Caribbean Province. Eleven of them have their more austral register in that territory, 16 in Santa Catarina and 6 in Rio Grande do Sul, Brazil. The taxa of dominant Mollusks with the greatest number of registers Codakia pectinella, Finella dubia, Gouldia cerina are found within that area. The only exception is Heleobia australis nana, which has its more austral limit in Rio Grande do Sul and the more septentrional limit in São Paulo.

Four facies can be found in the depositional environments: sandy­muddy, sandy, muddy­sandy and muddy. An energy variation is recorded in eight drilling cores with coarser sediments ocurring during the maximum transgressive phase and fine sediments during the regressive phase. Two environmental cycles are detected: the marine cycle and the lagoonal one. The first one coincides with a transgressive phase and the second one with a regressive phase.

Based on previous datafrom a nearby shell bank, it is possible to correlate the evidences with an event of more or less 5,100 years B.P. from a initial transgressive moment to a maximum transgressive one.

This characterizes an increase of the oceanicity with gradual decrease of this influence - transgressive to regressive - until the establishment of a typical lagoonal environment with a clear evidence of continentality.

MALACOFAUNA, PALEOECOLOGIA E BIOFÁCIES DE SEDIMENTOS HOLOCÊNICOS DA PLANÍCIE COSTEIRA DE IMBITUBA E IMARUÍ, SANTA CATARINA, BRASIL

MALACOFAUNA, PALAEOECOLOGY AND BIOFACIES OF HOLOCENE SEDIMENTS FROM THE COASTAL PLAIN AT IMBITUBA AND IMARUÍ, SANTA CATARINA, BRAZIL

Inga Ludmila Veitenheimer Mendes (1993)

Adviser: Ieda Regina Forti Esteves

Abstract

A study of the D'Una river, belonging to the municipalities of Imaruí and Imbituba, Santa Catarina, Brazil, is conducted from drilling holes samples, based on the taphocenosis of mollusks and the accompanying paleobiota. Its aim is to identify paleoenvironments and to correlate them with oscillations of the sea level which happened along the Brazilian coast during the Holocene.
The present study analyzes strata obtained from 25 drilling holes. The selection, identification, counting and characterization of Mollusca taxa, basic group of the study, and the accompanying paleobiota were carried out. For the paleoecological analyses, the following parameters and ancillary elements were used: Mollusk Specific Diversity Index, Relative Abundance of Faunal Groups, Dominant Mollusks, Preservation State of Dominant Mollusks, Present Habitat of Dominant Mollusks, Present Habitat of Accompanying Fauna, knowledge of present mollusks found in nearby areas and identification of successional biofacies and Cluster Analysis.
Eighty six Mollusca species are identified. From those, 20 have in the Caribbean Province of São Paulo State their southernmost present record, whereas three of them have the State of Rio Grande do Sul (Brazil) as their northernmost present record. Regarding the accompanying paleofauna, are registered species of Foraminifera, Porifera, Cnidaria, Cirripedia, Ostracoda, Echinoidea and Pisces. The Index of Specific Diversity varies from zero to 3.3060. The predominant taxa of Mollusca are: Crepidula spp., Caecum spp., Finella dubia, Heleobia australis nana, Odostomia spp., Petaloonchus sp., Acteocina spp., Parvanachis spp., Anomalocardia brasiliana, Corbula spp., Codakia pectinella, Dosina concentrica, Gouldia cerina, Mytilidae and Ostreidae. Identified successional biofacies are connected to the oscillations of the sea level during the Holocene.
Two transgressions related to D'Una river area under study can be identified. According to the time analysis of shells from shell­middens and mollusk shell banks submitted to radiocarbon, it is possible to establish an older event with 5,100 years B.P. (sequences IV, V and VI) and another one with 3,600 years B.P. (sequences VIII, IX, X and XI). The depositional environments during the transgressions are characterized as lagoonal or estuarine and shallow coastal sea of low energy, the latter being represented by bays or bights. The predominant average temperatures at the time of transgressive events were probably higher than the present ones.

MORFODINÂMICA E EVOLUÇÃO DE CAMPOS DE DUNAS TRANSGRESSIVOS QUATERNÁRIOS DO LITORAL DO RIO GRANDE DO SUL

Caroline Thaís Martinho (2008)

Adviser: Sérgio Rebello Dillenburg

Resumo

O trecho do litoral do Rio Grande do Sul entre Torres e Mostardas apresenta três tipos diferentes de barreiras: progradantes, agradantes e retrogradantes, e campos de dunas transgressivos se desenvolvem sobre todas elas. Contudo, o tamanho e a morfologia desses campos variam ao longo da costa, apresenta mudanças nas últimas décadas. Este trabalho analisou os fatores responsáveis pelas variações espaço-temporais na morfologia dos campos de dunas e compreender sua evolução ao longo do Holoceno médio e tardio (últimos 5000 anos A.P.).
De Mostardas a Jardim do Éden, as altas energia de ondas e taxas de transporte longitudinal de sedimentos (TLS) provocam a erosão da linha de costa e a conseqüente retrogradação da barreira. Essa erosão disponibiliza maior volume de areia para o transporte eólico. Desse modo, o alto aporte sedimentar juntamente com a baixa umidade e o alto potencial de deriva (PD) eólica, observados nessa região, são responsáveis pela formação de grandes campos de dunas.
De Atlântida Sul a Torres, trecho adjacente às escarpas da Serra Geral, a umidade é alta, devido à precipitação orográfica e o PD eólica é menor devido à barreira topográfica. A baixa energia de ondas e a desaceleração do TLS, observados nessa região, criam balanço positivo de sedimentos, promovendo a progradação da barreira. Contudo, a baixa energia de ondas não tem capacidade de transportar grandes volumes dessa areia para o estirâncio e pós-praia. Assim, apesar do balanço positivo e do caráter progradante da barreira, o volume de areia disponível para o transporte eólico é menor. Com o baixo aporte sedimentar, alta umidade e baixo PD eólica, os campos de dunas dessa região são mais estreitos e restritos.
Variações climáticas foram observadas ao longo das últimas décadas. De 1948 a 2003 a precipitação aumentou e o PD eólica diminuiu de 1964 a 1988. Os campos de dunas de Atlântida Sul a Torres, menores e com menor volume de areia, responderam rápido ao aumento da precipitação e decréscimo no PD eólica, e encontram-se em estágio avançado de estabilização. Os campos de dunas de Mostardas a Jardim do Éden, maiores e com maior volume de areia levaram maior tempo para iniciarem sua estabilização e crescimento da vegetação. Quanto maior o volume de areia e o tamanho do campo de dunas, maior será o intervalo de tempo para sua estabilização.
O estudo da evolução dos campos de dunas foi realizado a partir de análise estratigráfica. Analisando as idades 14C de paleossolos e informações sobre paleoclima observou-se que os três períodos principais de formação de solo (de 4820 a 3970 anos cal A.P.; em 2760-2460 anos cal A.P.; e de 1570 a 710 anos cal A.P.) coincidem com períodos de clima mais úmido. Este fato indica que o clima pode estar controlando a evolução dos campos de dunas desde pelo menos 5000 anos A.P.. A partir de informações estratigráficas, idades de paleossolos e descrição de fácies, 10 fases de ativação e estabilização eólica foram reconhecidas no litoral médio do RS.
 

MORPHODYNAMICS AND EVOLUTION OF QUATERNARY TRANSGRESSIVE DUNE FIELDS OF THE STATE OF RIO GRANDE DO SUL LITORAL

Abstract

The Rio Grande do Sul coastal stretch between Torres and Mostardas present three different types of barriers: progradational, aggradational and retrogradational, and transgressive dunefields have developed over all of them. Nevertheless, the size and the morphology of these dunefields vary along the coast and have been changing over the last decades. The aim of this study is to analyze the factors responsible for the spatio-temporal variations in the dunefields morphology and to understand their evolution through mid and late Holocene (last 5000 yrs BP).
From Mostardas to Jardim do Éden, the wave energy and the longshore sediment transport (LST) promote the coastline erosion and, consequently, the barrier retrogradation. The erosion increases the volume of sand available to the aeolian transport. Thus, the large sand supply along with the observed low humidity and high wind drift potential (DP) are responsible for the formation of large transgressive dunefields.
From Atlântida Sul to Torres, coastal stretch adjacent to the Serra Geral scarps, the humidity is higher due to the orographic precipitation and the wind DP is lower due to the topographic obstruction. The low wave energy and the decrease of the LST, observed in this region, create a positive sediment imbalance, promoting barrier progradation. Nevertheless, the low wave energy is not capable to transport large volumes of sand to the foreshore and backshore. Thus, despite the positive imbalance and the progradational character of the barrier, the volume of sand available to aeolian transport is lower. With low sand supply, high humidity and low wind DP, the dunefields in this area are narrow and restrict.
Climatic changes were observed through the last decades. From 1948 to 2003 the precipitation has increased and the wind DP has decreased from 1964 to 1988. The dunefields from Atlântida Sul to Torres, smaller and with low sand volume, have responded faster to the increase in precipitation and the decrease in the wind DP, and nowadays are in an advanced stabilization stage. The dunefields from Mostardas to Jardim do Éden, larger and with high amount of sand, have taken longer to initiate the stabilization processes and vegetation growth. The larger the sand volume and the dunefields size, the longer it will be the time period to stabilize it.
The study of the dunefield evolution was realized by stratigraphic analysis. Analyzing the 14C ages from paleosol layers and the paleoclimatic information, it was observed that the three main soil formation periods (from 4820 to 3970 cal yrs BP; in 2760-2460 cal yrs BP; and from 1570 to 710 cal yrs BP) coincide with periods of wetter climate. This fact indicates that the climate might be controlling the dunefield evolution since at least 5000 yrs BP. From stratigraphic information, paleosol ages and facies description, 10 phases of aeolian activation and stabilization were recognized in the RS mid littoral.