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

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GEOLOGIA E ESTRATIGRAFIA DO GRUPO TUBARÃO - FOLHA BARÃO DO TRIUNFO, MUNICÍPIO DE GUAÍBA - RS

GEOLOGY AND STRATIGRAPHY OF THE TUBARÃO GROUP - BARÃO DO TRIUNFO QUADRANGLE, GUAÍBA MUNICIPALITY - RS

Zuleika Carreta Correa da Silva (1970)

Adviser: Paulo Miranda Figueiredo Filho

Abstract
This dissertation deals with the geological mapping and the stratigraphy of the sedimentary rocks of Tubarão Group in Barão do Triunfo Quadrangle, Rio Grande do Sul State.

The sedimentary sequences are related to Itararé Sub­Group and Rio Bonito Formation, which belongs to Sub­Group Guatá.

Fossilized leaves of both Glossopteris and Gangamopteris Floras showed that the rocks of Tubarão Group are of Lower Permian age.

The sediments were considered to be formed in a fluvio­lacustrine environment and the rocks of Sub­Group Itararé are related to a glacial climate.

The evaluation of clay resources in the area of Potreiro Grande indicated that kaolinite is worth exploiting.

FORMAÇÃO ROSÁRIO DO SUL

ROSARIO DO SUL FORMATION

Natálio Gamermann (1971)

Adviser: Paulo Miranda Figueiredo Filho

Abstract
The limit between Permian and Triassic rocks is a rather controversial aspect of the stratigraphy of the Gondwana of the Paraná Basin.

In Rio Grande do Sul State the controversy lies on the identification of the beds situated between the Estrada Nova and Botucatu Formations. These beds have been interpreted as different units, thus receiving different names.

The Santa Maria fossiliferous beds, which occur only and locally in Rio Grande do Sul, are also included in this stratigraphic problem.

The identification of the Rosário do Sul Formation in the geologic column of Rio Grande do Sul not only solves the problem of plurality of names and interpretations, but also unifies the litho­stratigraphy, establishing type­sections and describing the characteristics of the adjoining formations. As a result, the limits of the Rosário do Sul Formation can be easily recognized.

The Rosário do Sul Formation includes all the red beds situated between the Estrada Nova and Botucatu Formations. It is subdivided into two facies; one is tipically fluvial, with flood plain characteristics, and the other is a fossiliferous facies, with lacustrine sediments, of restricted occurrence, known as Santa Maria. Based on the paleofauna of this facies, a Triassic age was determined for the Rosário do Sul Formation. The upper and lower contacts of this formation are, respectively, with the Botucatu Sandstone and the Estrada Nova Formation and exhibit a transitional nature.

The Rosário do Sul Formation can be genetically and temporally correlated with the Pirambóia Beds, whose best exposures can be seen in São Paulo State. Considering that Pirambóia is, in fact, thicker than it has usually been described, and that it is a unit which can be mapped, it is suggested here that further studies be made on these aspects, so as to bring the Pirambóia facies to a Formation status into the São Bento Group.

CONTRIBUIÇÃO À GEOLOGIA DA REGIÃO DE SANTA MARIA, RS

CONTRIBUTION TO THE GEOLOGY OF THE SANTA MARIA AREA, RS

Carlos Alfredo Bortoluzzi (1972)

Adviser: Paulo Miranda de Figueiredo Filho

Abstract
The region surrounding the city of Santa Maria (Rio Grande do Sul State, southern Brazil) was surveyed, so that the present dissertation could offer up­to­date evidences and conclusions on the stratigraphical characteristics of the Santa Maria Formation (Triassic) in its type­area.

As this formation comprises some of the most conspicuous sediments of the Gondwana sequence in Rio Grande do Sul State, it was also decided to study its stratigraphic relationships to the other units of the São Bento Group in the same area, from stratigraphic, sedimentological and structural points of view.

Surface geologic studies were complemented by data provided by sedimentological, petrographic and clay mineralogy (XRD) analyses. The obtained results led to the following conclusions:

a) the São Bento Group in Rio Grande do Sul State comprises four geologic formations, from bottom to top: Rosário do Sul s.s., Santa Maria, Botucatu and Serra Geral;

b) the Rosário do Sul Formation (sensu Gamermann, 1970) must have its stratigraphic range restricted, so as to include only fluvial clastic sediments exhibiting through cross­bedding and lying between the Estrada Nova (Permian) and Santa Maria (Triassic) Formations; in reference to this, it is here proposed that it should be named Rosário do Sul Formation (s.s.);

c) the Santa Maria Formation should be mantained as a valid lithostratigraphic unit, which exhibits a lower part, made up of conglomerates, sandstones, siltstones and shales with the Thïnnfeldia- ­Dicroidium flora, and an upper part, mainly siltic, associated with a well­known reptilian paleofauna;

d) the contact between the Rosário do Sul (s.s.) and Santa Maria Formations is conformable, but the latter exhibits an unconformable contact with the overlaying Botucatu Formation;

e) within the studied area, the Botucatu Formation can be divided into a sandy/muddy lower unit, of fluvial­lacustrine origin, which gradually passes upward into the eolian upper unit;

f) the contact between the Botucatu Formation and the Serra Geral basic lavas is locally unconformable.

CONTRIBUIÇÃO À PALEONTOLOGIA ESTRATIGRÁFICA DO GRUPO PASSA DOIS NO RIO GRANDE DO SUL

A CONTRIBUTION TO THE STRATIGRAPHIC PALEONTOLOGY OF THE PASSA DOIS GROUP IN RIO GRANDE DO SUL

Maria do Carmo Lima e Cunha (1972)

Adviser: Paulo Miranda de Figueiredo Filho

Abstract

The present dissertation deals with the study of the fossil content of four geologic profiles made up of sediments belonging to the Passa Dois Group (Permian of Rio Grande do Sul State, southern Brazil) and including the four facies established for this group by Figueiredo Fº (1971).

The combined faciological and paleontological observations revealed the following data:

a) the identified fragments of crustaceans (Liocaris) and vertebrates (mesosaurid reptiles) are found in the calcareous lenses of the lower facies of the Irati Formation;

b) fragments of crustaceans (Pygaspis) and plants (Glossopteris Flora) occur, as imprints, in the pirobituminous shales of the lower facies of the same formation;

c) teeth and fish scales (Palaeoniscidae) occur in siltstones at the base of the lower facies of the Estrada Nova Formation;

d) bivalvian mollusks (Cowperesia?), identified in calcareous concretions, septaria­like, associated to sand beds of the upper facies of Estrada Nova Formation, are for the first time registered in Rio Grande do Sul State; plants of the Glossopteris Flora occur at the bottom of this facies.

CONTRIBUIÇÃO À ESTRATIGRAFIA E SEDIMENTOLOGIA DA FORMAÇÃO CAMARINHA (PRÉ­DEVONIANO DO ESTADO DO PARANÁ)

A CONTRIBUTION TO THE STRATIGRAPHY AND SEDIMENTOLOGY OF THE CAMARINHA FORMATION, PRE­DEVONIAN OF PARANÁ STATE

José Henrique Popp (1972)

Advisers: João José Bigarella,

Paulo Miranda de Figueiredo Fº e

Riad Salamuni

Abstract

Main stratigraphical and sedimentological features of the Camarinha Formation (Pre­ ­Devonian) are presented in this dissertation.

Stratigraphy is discussed based on three typical sections.

Primary sedimentary structures are described in detail, aiming to solve the problem of the origin of the Camarinha deposits.

The data gathered suggest depositional conditions of the "molasse" type.

MAPEAMENTO GEOTÉCNICO DE MORRETES E MONTENEGRO (RIO GRANDE DO SUL - BRASIL)

ENGINEERING GEOLOGICAL MAPS OF MORRETES AND MONTENEGRO (RIO GRANDE DO SUL, BRAZIL)

Flávio Koff Coulon (1973)

Adviser: Paulo Miranda de Figueiredo Filho

Abstract

By means of its text and evidences gathered from maps of the Morretes and Montenegro quadrangules, this dissertation aims at establishing some general criteria for the elaboration of engineering geological maps at a regional scale in Rio Grande do Sul State, Brazil.

In the presented maps, which cover a type­area in this State, some engineering geological types of material were individualized and identified by a special notation composed of symbols (letters and numbers), regardless its location in the area.

In order to use adequately the information contained both in the text and maps, a throughout understanding of the mapping code isneeded; thus, it was sufficiently detailed and explained.

The major engineering geological data of this study were collected during highway surveys and in several Offices related to them. However, the detailed information offered by the text and maps, may also be adopted for different specializations within Applied Geology.

In the first part of the text, the present status of engineering geological mapping in several countries is discussed. There was no intention of establishing comparisons in doing so, but only of reporting on the ways and the basic conceptions that each country is giving to this type of mapping.

ESTUDO DOS ARENITOS "INTERTRAPPS" DA FORMAÇÃO SERRA GERAL NA REGIÃO DE SANTA MARIA

"INTERTRAPP" SANDSTONES OF THE SERRA GERAL FORMATION IN THE REGION OF SANTA MARIA

Péricles Veiga (1974)

Adviser: Paulo Miranda de Figueiredo Filho

Abstract

The mapping of an area near the city of Santa Maria, Rio Grande do Sul State, and detailled geologic profiles are presented.

The presence of at least four basaltic lava flows of the Serra Geral Formation was detected. Three intertraps of eolian sandstones, with thicknesses varying from 30cm to 50m, were found between the basaltic levels.

Sedimentary analyses were carried out in the intertrap sandstones, as well as in the eolian sandstones of Botucatu Formation, which occur immediately below the Serra Geral Formation.

We can conclude that the intertrap sandstones are intimately related to the eolian sandstones of the Botucatu Formation, and they represent a continuation of the sedimentation during the first lava flows. Consequently, we can consider that the contact Botucatu­Serra Geral is in agreement with the time of deposition and the Botucatu Formation is contemporaneous with the first basaltic flow of the region, which presents, by K/Ar process, approximate ages of 120 m.a., according to personal information by Dr. U. G. Cordani, of the Institute of Geochronology (São Paulo University), who analyzed five simples of the extrusive rocks of the Santa Maria area.

ASPECTOS GEOGRÁFICOS E GEOLÓGICOS DA REGIÃO METROPOLITANA DE PORTO ALEGRE (NORTE)

GEOGRAPHIC AND GEOLOGIC ASPECTS OF THE NORTH METROPOLITAN REGION OF PORTO ALEGRE

Enio Medeiros Ramos (1975)

Adviser: Paulo Miranda de Figueiredo Filho

Abstract

The present dissertation aims to provide the continuity of the geologic mapping of the northern region of Porto Alegre, the capital of Rio Grande do Sul State. It was thus provided the joining of the Morretes and Montenegro Quadrangles to the Gravataí and Taquara Quadrangles. The geology of the São Leopoldo and Novo Hamburgo Quadrangles is described.

The surveyed area constitutes the physical basis of the northern metropolitan region of Porto Alegre and, owing to the diversity of industrial and commercial activities it lodges as well as its high populational density (the largest in the State), the geoeconomical importance of this area is obviously very great.

CONTRIBUIÇÃO AO ESTUDO DAS ESTRUTURAS SEDIMENTARES NA FORMAÇÃO RIO BONITO - ESTADO DE SANTA CATARINA

CONTRIBUTION TO THE STUDY OF SEDIMENTARY STRUCTURES IN THE RIO BONITO FORMATION - SANTA CATARINA STATE

Ana Emília Mendes Piccoli (1975)

Adviser: Paulo Miranda de Figueiredo Filho

Abstract

This dissertation deals with the Rio Bonito Formation in relation to its sedimentary structures and environmental significance. The study was based on the analysis of nine cores from the coal basin located in the southern part of the State of Santa Catarina. The drill holes were alligned in a North­South direction. Outcrops were also studied for comparative purposes.

The base of this formation consists mainly of arkosic and feldspatic sandstones. The medium part contains siltstones and shales, partly carbonaceous in nature. The top consists mainly of quartzitic sandstones associated with the upper coal seams; the sandstones are finer than those occurring at the base.

The Barro Branco coal seam is continuous all over the studied area. Other coal seams are limited to isolated zones in the basin and probably represent topographic lows in the sedimentary environment.

Several kinds of sedimentary structures occur in the Rio Bonito Formation. The stylolites found may be used in determining stratigraphic levels. Stylolites occurring bellow the lower coal seams are filled with calciferous material. Those above the lower coal seams are filled with argilo­carbonaceous material.

The top layers of the Rio Bonito Formation are similar to the Palermo layers; both have dark siltstones with flaser structures and bioturbation. The contact between the two formations is gradational.

The sediments of the Rio Bonito Formation studied here were deposited in a typical deltaic environment. This is indicated by the sedimentary structures and lithologies present in that area. The absence of marine levels and fossils denies a marine delta hypothesis.

GEOLOGIA DO HOLOCENO COSTEIRO DA ÁREA DE RIO GRANDE, RS

GEOLOGY OF THE COASTAL HOLOCENE OF RIO GRANDE AREA, RS

Moanilda Fróes Godolphim (1976)

Adviser: Paulo Miranda de Figueiredo Filho

Abstract

This dissertation represents an attempt to identify the elements that permit the division of Holocene in the Coastal Plain of Rio Grande do Sul State by the use of morphological criteria in order to determine its stratigraphy.

The Holocene transgression moved the shoreline across the exposed upper surface of the Pleistocene barrier to a position several kilometers inland of its present position. During the last six thousand years, the shoreline has regressed by the deposition of a sheet­like body of littoral sand.

During this depositional regression, the sea­level has changed and each small oscillation built a deposit of sand ridges. The sand ofthe individual ridges coalesced to form a sheet sand with a furrowed upper surface.

It was possible to ascertain the correspondence between the seven series of beach­ridges and the small sea­level flutuation that occurred at the same time.

The Holocene deposits were treated in terms of their original environments and their morphologic features, what allowed the establishment of geomorphological criteria.

These criteria were used for age differentiation of Holocene successions and led to the determination of the Holocene stratigraphic sequences in the Coastal Plain of Rio Grande do Sul.

GEOLOGIA E PALEOGEOGRAFIA DA RESTINGA DA LAGUNA DOS PATOS - RS

GEOLOGY AND PALEOGEOGRAPHY OF THE LAGUNA DOS PATOS SAND BAR - RS

Flora Zeltzer (1976)

Adviser: Renato Rodolfo Andreis

Abstract

The purpose of this research is to analyze the geological and paleontological aspects of the Patos Lagoon's Sand Bar, which consists of a sandy ribbon that separates the Patos Lagoon from the Atlantic Ocean.

The geological and geomorphological mapping of the Northeast part of the State Coastal Province as well as the analysis of the mechanisms that have created it revealed the following aspects:

- The Sand Bar is constituted of a sequence of multiple barriers whose origin is related to the relative level fluctuations of the sea during the Quaternary Era, and also to the climate and supplying rate of sedimentary materials.

- The vestiges of transgressions that occurred gradually in a decreasing height level were denominated: Viamão, Palmares, and Mostardas (Pleistocene); Desertas, Conceição, and Bojuru (Holocene), according to Godolphim 1976.

This dynamics allied to climate changes seems to have helped the development of depositional environments (marine, lagoon, and aeolian) characterized by their own sedimentation, which has lasted until the present days.

The research showed the possibility of correlation with similar events observed in other areas of the State Coastal province as well as in much further areas.

PALEOAMBIENTES DA FORMAÇÃO PALERMO NO SUDESTE DO ESTADO DE SANTA CATARINA - BRASIL

PALEOENVIRONMENTS OF THE PALERMO FORMATION IN THE SOUTHEASTERN PART OF SANTA CATARINA STATE - BRAZIL

Nirlei Troller Habekost (1976)

Adviser: Renato Rodolfo Andreis

Abstract

This dissertation deals with sedimentary structures. Specifically, it attempts to reconstruct the environment in which the sedimentary structures of the sediments of the gondwanic Palermo Formation, in the southeastern part of the State of Santa Catarina, Brazil, were formed.

Six cores were studied and described in detail. The cores came from the four areas studied by DNPM and CPRM, as reported in "Relatório Integrado do Projeto Carvão de Santa Catarina" (Complete Report of the Santa Catarina Coal Project). The six cores were drawn at about equal distances along an approximately north­south line, between the localities of Capivara Alta (Lauro Müller) and Lagoa dos Bichos (Araranguá).

In the study area, the Palermo Formation is made up mainly of sandy siltstones and siltstones. Fine sandstones are found less frequently. The gray hues of the sediments are predominant.

In general, mechanical (many kinds of laminations, flasers, etc.) and biogenic (only bioturbation) structures are the most common, while the chemical ones are rarer.

The abundance of the primary sedimentary structures made possible the determination of the areal and vertical distribution of the types referred to, based on sequence deposition cycles.

It was concluded that the sediments of the Palermo Formation in southeastern Santa Catarina were deposited in a transitional environment, probably a tidal flat related to the intertidal zone.

ESTUDO GEOLÓGICO DA REGIÃO DE PEDRA BRANCA, BAGÉ, RIO GRANDE DO SUL, COM ENFOQUE ESPECIAL A OCORRÊNCIAS DE MÁRMORE

GEOLOGICAL STUDY OF THE PEDRA BRANCA AREA, BAGÉ, RIO GRANDE DO SUL, WITH SPECIAL EMPHASIS ON THE MARBLE OCCURRENCES

Nelson Amoretti Lisboa (1977)

Adviser: Renato Rodolfo Andreis

Abstract

A geologic study of the Pedra Branca region - an area of about sixty square kilometers, located at the northeast of Bagé, in the State of Rio Grande do Sul, was made. Special interest is given to the marble occurrences, which constitute, along with quartzites and migmatites, the pre­Cambrian Cambaí Group.

Two different types of occurrences were found. One of them, named Jazida da Chácara do Cotovelo, with about 200 acres, is here particularly detailed, owing to its economical aspects.

PALEOCORRENTES DA FORMAÇÃO BOTUCATU ENTRE OS GRAUS DE JAGUARI E SÃO FRANCISCO DE ASSIS E ALGUMAS CONSIDERAÇÕES ESTRATIGRÁFICAS SOBRE O GRUPO SÃO BENTO - RS

PALEOCURRENTS OF THE BOTUCATU FORMATION BETWEEN THE JAGUARI AND SÃO FRANCISCO DE ASSIS DEGREES AND SOME STRATIGRAPHICAL CONSIDERATIONS ON THE SÃO BENTO GROUP, RS

Issa Chaibem Jabur (1979)

Adviser: Renato Rodolfo Andreis

Abstract

The research that has been carried out in the southwestern sector of the State of Rio Grande do Sul represents, first of all, an attempt to collect by means of statistical presentations, information about the preferential course of the winds responsible for the sedimentation of sand dunes in the Botucatu desert.

Similarly, the compilation of data, necessary for the interpretation of azimuthal values and useful in determining the dominant currents in the geographical area under analysis, has resulted, in stratigraphic terms, in defining the progression underlying the Aeolian deposits.

This study has been extended in order to comprise to the relationships of subjacent lithologies, foreseeinggreater unity among different groups engaged in field work.

Based upon the observations in the field, the denomination "Caturrita" Formation has been applied to the sediments with fluvial characteristics underlying the aeolian sandstones of the Botucatu Formation.

This research is also related to the study of the geological sections drawn in the States of São Paulo and Paraná, making it possible to appreciate to a fuller extend the extension of the adopted stratigraphic divisions and the possible correlations between the units under study and their image farther north of the basin.

CONTRIBUIÇÃO À ESTRATIGRAFIA DA REGIÃO DE GRAVATAÍ - RIO GRANDE DO SUL - BRASIL

CONTRIBUTION TO THE STRATIGRAPHY OF THE GRAVATAÍ REGION - RIO GRANDE DO SUL - BRAZIL

Henrique Carlos Fensterseifer (1979)

Adviser: Paulo Miranda de Figueiredo Filho

Abstract

This dissertation deals with the study of the lithologic features, geological­structural aspects, and the relation among the different lithostratigraphic units of the Gravataí region, near Porto Alegre, Rio Grande do Sul State.

Pre­Cambrian units, related to the Sul­Riograndense Shield, Late Paleozoic to Late Mesozoic units, comprising the Paraná Basin sequences, as well as Cenozoic units, characterized by sediments of the Patos Group, and Recent sedimentary deposits were recognized.

The Pre­Cambrian units are represented by heterogeneous migmatites, gnaisses, and granites of the Cambaí Group (Middle to Pre­Cambrian). The contacts of these lithologies have not been observed.

The sedimentary sequences of the Paraná Basin - Late Paleozoic to Late Mesozoic - are represented by the Rio Bonito and Palermo Formations, Guatá Sub­Group, Tubarão Group; the Irati and Estrada Nova Formations, Passa Dois Group; and the Rosário do Sul and Botucatu Formations, São Bento Group. The Serra Geral Formation, São Bento Group, is represented by diabase intrusives. Some of the studied formations present lithological variations and stratigraphic changes have also been registered.

The Rio Bonito Formation presents two distinct depositional intervals: 1) a lower (basal) interval represented by fluviatile, lacustrine or lagoonal, paludal, and deltaic facies; and 2) an upper interval characterized by a transgressive lagoonal facies.

The Tiaraju (lower) and Valente (upper) facies as well as a sandy facies - atypical and stratigraphically situated between the other two facies, were determined for the Estrada Nova Formation.

The upper and lower contacts of the Rosário do Sul Formation are discussed and the possible occurrences of the Caturrita Member, Botucatu Formation, are analized.

Finally, a correlation between the Gravataí and Graxaim Formation was established, and some considerations on the paleo-environmental characteristics and on the stratigraphic relations of both formations concerning the Guaíba and Itapoã Formations were made.

ESTRATIGRAFIA DO GRUPO SÃO BENTO NA REGIÃO DE SANTA MARIA E PALEOCORRENTES DA FORMAÇÃO BOTUCATU

STRATIGRAPHY OF THE SÃO BENTO GROUP IN THE REGION OF SANTA MARIA AND PALEOCURRENTS OF THE BOTUCATU FORMATION

Edgardo Ramos Medeiros (1980)

Adviser: Renato Rodolfo Andreis

Associated Adviser: Gerardo Eugênio Bossi

Abstract

A stratigraphic review was made in Santa Maria region, Rio Grande do Sul State, Brazil, where the Rosario do Sul, Santa Maria, Botucatu and Serra Geral Formations were studied in some detail.

The Alemoa and Passo das Tropas facies of the Santa Maria Formation (Bortoluzzi 1974) were considered as members. On the other hand the Caturrita Member of the Botucatu Formation was individualized as Caturrita Formation.

The statistic methods were used in the study of paleocurrents of the Botucatu Formation. The Agterberg & Briggs (1963) permitted to obtain a mean of N24° E for the main direction of the wind.

The statistic data showed that the dunes of the Botucatu desert in Santa Maria region were Barchans.

AS FORMAÇÕES RIO DO SUL E RIO BONITO NO SUDESTE DO ESTADO DO PARANÁ - PALINOLOGIA, IDADES E SUBSÍDIOS PALEOECOLÓGICOS

THE RIO DO SUL AND RIO BONITO FORMATIONS IN SOUTHEASTERN PARANÁ STATE - PALYNOLOGY, AGES AND PALAEOECOLOGICAL SUBSIDIES

Sérgio Luiz Thomaz (1980)

Adviser: Renato Rodolfo Andreis

Abstract

This dissertation refers to palynological studies of some samples from the boreholes 1­PP­12­PR, 1­PP­16­PR, 1­IV­03­PR and 1­PP­17­PR, located in the southeastern part of the State of Paraná; this region includes the areas of São Mateus do Sul and Ipiranga.

A synthesis of the lithostratigraphy is presented in order to understand the palaeoenvironment of sedimentary rocks under investigat-ion.

An informal subdivision of the Rio Bonito Formation in lower sequence and upper sequence, owingto the interfingering of the sedimentary bodies of rocks is used, according to Pilatti (1980), who studied the sedimentary structures of the same sequence.

The vertical distribution of twenty four guide palynomorphs allows the setting up of the biostratigraphic table. The occurrence of a Scolecodont is registered.

The sedimentary sequence studied corresponds to the bioestratigrapahic intervals H3 and K (Daemon & Quadros, 1970), and geochronologically, from Artinskian to Kungurian age.

A FORMAÇÃO RIO BONITO NO SUDESTE DO ESTADO DO PARANÁ - ESTRATIGRAFIA E PALEOAMBIENTES

THE RIO BONITO FORMATION IN SOUTHEASTERN PARANÁ STATE - STRATIGRAPHY AND PALAEOENVIRONMENTS

Fernando Pilatti (1980)

Adviser: Renato Rodolfo Andreis

Abstract

This dissertation presents a study which focuses upon the Rio Bonito Formation, located in the southern part of the State of Paraná, through the geologic examination of cores obtained in drilling for the prospection of coal deposits.

In the Rio Bonito Formation two sedimentary sequences can be distinguished. In the lower sequence predominate sandstones, which range from fine to medium­grained, locally coarse­grained, and conglomeratic, feldspathic, immature sandstones presenting mainly massive layers, medium and small size cross lamination, and cut­and­fill structures associated with small coal seams. Secondarily, there are siltstones and diamictites.

The upper sequence consists of greenish gray siltstones and shales as well as calciferous levels with algal structures. On the top of the sequence predominate greenish gray,well­selected finer sandstones with small size ripple and cross lamination and flat parallel lamination levels; bioturbation also occurs.

A detailed description of cores and a working up of several lithofacies and sand/shale percentage graphs, associated with the study of the lithology, the texture and the sedimentary structures, have made it possible to make a paleoenvironmental interpretation.

The lower sequence of the area in question was deposited under continental influence in a typical alluvial flat environment, while the upper sequence was deposited in a transitional environment, presenting lagoonal facies, tidal flats, beaches and barriers.

Contact relations have been established with the Itararé Group and Palermo Formation. The tectonic influences of the Ponta Grossa Arc were also observed and registered.

ANÁLISE PALEOAMBIENTAL DO GRUPO ITARARÉ NA ÁREA DE GRAVATAÍ - MORUNGAVA, RS

PALAEOENVIRONMENTAL ANALYSIS OF THE ITARARÉ GROUP IN THE GRAVATAÍ - MORUNGAVA AREA, RS

Paulo Roberto Corrêa Funchal (1980)

Adviser: Zuleika Carreta Corrêa da Silva

Abstract

The study of sedimentary structures and ciclicity of six well­cores from the Itararé Group evidenced the more significant palaeoenvironmental features at Gravataí­Morungava area.

The results, comprising several sub­environments, reflect the complexity of the lithologic variations found along the profiles.

The depositional system is variable and intercomunicative, characteristic of periglacials areas, with the development of lakes (varve rocks), small rivers (ortoconglomerates and sandstones) and clastic fans (diamictites), followed vertically by marsh deposits (siltstones) in flatter areas, with a generalized growth of vegetation and local peats (beds of coal, discontinuous and of little thickness).

ESTRATIGRAFIA E EVOLUÇÃO DO QUATERNÁRIO DO PLANO COSTEIRO NORTE DA ILHA DE SANTA CATARINA

STRATIGRAPHY AND EVOLUTION OF THE QUATERNARY OF THE NORTH COASTAL PLAIN OF THE SANTA CATARINA ISLAND

Gerusa Maria Duarte (1981)

Adviser: Renato Rodolfo Andreis

Abstract

The coastal plain of the Northern part of the Island of Santa Catarina between 27°23' and 27°31' S, and 48°25' and 48°32'50" W, registers a series of transgressive and regressive events in the deposits that delineate its area. From a geological and geomorphic point of view these phenomena marked the area through erosive and depositional processes.

Seven Geologic Units that overput themselves over the time were characterized. The older four Units overput themselves vertically and are Pleistocene. The following three develop laterally in distinct time and are Holocene.

With their stratigraphic, sedi- mentologic, morphologic and altitudinal characteristics these Units make evident the environments and the processes which formed them and the recurrence of both. These characteristics registered four transgressive and three regressive processes. Of the two transgressive episodes related to three sea levels higher than the present, one is Pleistocene and the two others are Holocene in age, and the last one has a very short amplitude.

The regressive episodes go back one to the Pleistocene and two to the Holocene.

GEOLOGIA E ESTRATIGRAFIA DO MEMBRO TRIUNFO (FORMAÇÃO RIO BONITO) NA REGIÃO ENTRE RESERVA E IPIRANGA - ESTADO DO PARANÁ

GEOLOGY AND STRATIGRAPHY OF THE TRIUNFO MEMBER (RIO BONITO FORMATION) IN THE REGION BETWEEN RESERVA AND IPIRANGA - PARANÁ STATE

Antônio Jorge Vasconcellos Garcia (1982)

Adviser: Zuleika Carreta Corrêa da Silva

Abstract

The dissertation presents the results of the semi­detailed geological mapping of the Marins, Fazenda Marçal, Remanso, Morro Chato, Serra do Caixão, Tuneiras, Cerro Azul, and Irara regions between Reserva and Ipiranga, Paraná State.

374 outcrops, including 56 stratigraphic profiles and 8 boreholes (CPRM/MINEROPAR and NUCLAM) were described; and 2 stratigraphic sections, 13 geological sections and 2 stratigraphic diagrams were made.

Based on the sedimentological, petrographical, physico­chemical, palynological and paleobotanical data, a composed stratigraphic column was elaborated to the sedimentary carbonaceous and/or fossiliferous rocks.

The Triunfo Member of the Rio Bonito Formation, Guatá Group, was divided in two different sequences, according to the distinctive characteristics of the unities to the south and north of the studied area. Some of these sequences represent paleoenvironmental particularities, probably restricted, but the complete characterization of the sequences allowed the understanding of the sedimentary dynamics predominating in the area during the deposition.

In order to represent the probable geological evolution during the sedimentation, 5 paleostratigraphic profiles were drawn. A geological map, in scale 1:25:000, and a lithological map of the Triunfo Member showed the areal distribution of the outcroping sequences.

The region presents two main areas for coal exploitation: Marins­ ­Fazenda Marçal and Remanso­Morro Chato­Serra do Caixão. The coal seam is 50cm thick in Marins­Marçal and the estimated reserves reach 2,5 million tons ROM. In the Remanso area the coal seam is thinner and of lower quality than in Marins­Marçal area.

ESTUDO GEOLÓGICO DOS SEDIMENTITOS DO GONDWANA SUPERIOR NA REGIÃO DE CANDELÁRIA A SANTA CRUZ DO SUL, RIO GRANDE DO SUL

GEOLOGICAL STUDY OF UPPER GONDWANIC SEDIMENTS, FROM CANDELÁRIA TO SANTA CRUZ DO SUL REGION, RIO GRANDE DO SUL

Doris Ketzer Montardo (1982)

Advisers: Gerardo Eugenio Bossi e Mario C. Barberena

Abstract

Detailed stratigraphic profiles, geological mapping, cyclicity analyses, profile simulation, clay mineralogy and evaluation of the paleontological content led to the stratigraphical and paleoenvironmental characterization of the sedimentary gondwanic sequences that outcrop in the area covered by the Santa Cruz do Sul, Vera Cruz and Candelária Quadrangles (Rio Grande do Sul State, Brazil). Comparisons with other outcrop areas in the State permitted to bring the study to a regional scale.

The sediments represent the continental and epiclastic deposition which characterized the final phase of sedimentation in the southern border of the Paraná Basin. Lithostratigraphycally, they represent the Santa Maria and Caturrita Formations of the Rosário do Sul Group (according to ANDREIS et alii, 1980) and the Botucatu Formation of the São Bento Group.

The Santa Maria Formation is divided into two members. The lower one, Passo das Tropas Member, is made up of more than 40 meters of whitish conglomeratic sandstones and fine sandstones and red pelites deposited by rivers with low sinuosity and poorly developed aluvial plains. The upper Alemoa Member comprises 55 meters of massive red pelites, acumulated under eolic influence on loess paleoplains.

The Caturrita Formation comprises a fluvial sequence organized in fining­upwards cycles normally well­defined and composed of coarse to fine sandstones and red, brown or grayish pelites reaching a thickness of 60 meters in average. The deposition was conditioned by a anastomosed river system (according to Smith & Smith, 1980), and thus characterized by multiple, straight to sinuous, stable channels separated by wide and stable alluvial plains of areno­pelitic composition aggraded by events of overbank floods.

The Santa Maria and Caturrita Formations were deposited under the influence of paleoclimatic conditions characterized by middle to warm temperatures, with alternating rainy and prolongated dry seasons, similar to those prevailing in the present subtropical zones.

Fine to medium, well­sorted, orange sandstones represent the Botucatu Formation. They were accumulated as dunes mobilized by dry winds of continental provenance. Their thickness is highly variable (30 meters to absent), suggesting proximity to the austral border of the accumulation basin.

Geochronological data, provided by correlation of paleoherpetofaunas, indicate a Middle Anisian to Middle Carnian age to the Santa Maria Formation. The same data indicate an Upper Carnian to Norian age for the Caturrita Formation. The relative age atributed to the Botucatu Formation comprises the Lower to Middle Jurassic interval.

O PERMO­TRIÁSSICO DO RIO GRANDE DO SUL. UMA ANÁLISE SOB O PONTO DE VISTA DAS SEQÜÊNCIAS DEPOSICIONAIS

THE PERMO­TRIASSIC OF RIO GRANDE DO SUL. AN ANALYSIS UNDER THE POINT OF VIEW OF THE DEPOSITIONAL SEQUENCES

Ubiratan Ferrucio Faccini (1989)

Adviser: Mario C. Barberena

Abstract

The sedimentary and volcanic rocks of Upper Permian and Mesozoic age in Rio Grande do Sul State are subdivided into four chronostratigraphic units, in accordance with the depositional sequences concept. Those units were identified on the basis of the evaluation of faciologic, paleoenvironmental and fossiliferous attributes on a regional scale.

Unconformable surfaces, representing significant depositional gaps, were identified and characterize the following sequences, from bottom to top: (1) Sequence I, corresponding to the Rio do Rasto and Sanga do Cabral Formations, is made up of lacustrine, deltaic, fluvial and eolic facies, with a minimum basal Triassic age (Scythian Stage, 245 m.y.); (2) Sequence II, including the Passo das Tropas and Alemoa Members (Santa Maria Formation) as well as part of the Caturrita Formation, is composed of fluvial and lacustrine facies,which contain a rich paleoherpetofauna concerning the Ladinian­Lower Norian Interval (238­225 m.y.); (3) Sequence III, here defined for the first time, refers to fluvial sandstones occurring in the city of Mata (RS) and exhibiting an expressive record of silicified wood trunks, tentatively attributed to Late Triassic (Rethic Stage, 215 m.y.); (4) Sequence IV, combines the eolic deposits of the Botucatu Formation and the overlying basaltic flows of the Serra Geral Formation, whose main volcanic manifestations show radiometric ages between 150 and 115 m.y. (Jurassic­Early Cretaceous).

Finally, hypotheses about the genesis of each sequence characteristics are formulated, associated to their possible regional correlation, as inferred by the available faciologic, paleoclimatic and geotectonic parameters.

EVOLUÇÃO DO PREENCHIMENTO DO CÂNION DE TAQUIPE, NEOCOMIANO DA BACIA DO RECÔNCAVO, SOB O ENFOQUE DA ESTRATIGRAFIA MODERNA

EVOLUTION OF THE FILLING OF THE TAQUIPE CANYON, NEOCOMIAN OF THE RECONCAVO BASIN, UNDER THE FOCUS OF THE MODERN STRATIGRAPHY

Jane Leão de Amorim (1992)

Adviser: Jorge Carlos Della Favera

Abstract

Fault movements and lowering of the lake level had formed the Taquipe Canyon in the southern part of the Recôncavo Basin during the Aratu Stage (Barremiano/Hauteriviano).

The canyon fill consists of shales, marls and sandstones, and it was called the Taquipe Formation. This sedimentary section was deposited during the time corresponding to the ostracode subzones NRT's 005.4 up to 006.2 (Aratu). It resulted from resedimentation of the Pojuca Formation (sandstones and shales) via gravity­induced processes such as slumps, debris flows and turbidity currents, triggered by the lowering of the lake level and seismic quakes.

The basin sedimentation outside of the canyon does not correlate with the canyon fill because during its filling time the canyon acted as a sub­basin, where the lake level stood high, while in the basin the lake level was lowering and so different types of sedimentary environments developed.

Stratigraphic correlations within the canyon fill are difficult, due to the high frequency of erosional events in contrast to the "normal" sedimentation outside of the canyon, which is characterized by good stratigraphic markers.

SEQÜÊNCIAS DE ALTA FREQÜÊNCIA E ANOXIA NO NEO­ALBIANO DO CAMPO DE CHERNE, BACIA DE CAMPOS, BRASIL

HIGH FREQUENCY SEQUENCES AND ANOXY IN THE LATE ALBIAN OF THE CHERNE FIELD, CAMPOS BASIN, BRAZIL

Wilson Rubem Winter (1992)

Adviser: Rodi Ávila Medeiros

Associated Adviser: Nilo Chagas de Azambuja Filho

Abstract

The Namorado Turbiditic Complex of the Cherne Field, Campos Basin, Brazil, was analyzed from the point of view of the sequence stratigraphy paradigm.

Were defined eleven sedimentary facies and their genetic association, as well as the geologic model for the turbiditic sandstones distribution. The resulting deposits were stacked up in a structural depression, formed in the Late­Albian. The medium thickness is about 130 meters, and was deposited in 0.46 M.y.

These facies were grouped in three distinct genetic units (depositional systems): the lower one, interpreted as a channel complex, is composed of coarse­ ­grained sand deposits formed by traction/suspension processes. The intermediate one is composed of coarse/medium­grained sand deposits dominated by suspension processes, and interpreted as channelized lobes. The other one consists of carbonaceous­clay facies association interpreted as the result of hemi-pelagic sedimentation and last pulses of turbiditic flows deposition.

Sand facies represent the lowstand system tract which is the principal tract occurring in the high frequence depositional sequences (fourth­order, sensu Vail et al., 1990) mapped in the field area.

These fourth­order sequences were grouped as the lowstand system tract of a third­order sequence (composed sequence) whose deposition spans the Vraconian Stage (Late Albian).

The sedimentary sucession analyzed represents a transgressive event that resulted from the interaction between the rate of accomodation development and sediment influx.

The Aptian­Albian anoxic event (OAE­1, Schlanger & Jenkyns, 1976) is represented by deterministic black shales, associated with the turbiditic deposits that form the radioactive Y marker.

SEQÜÊNCIAS CONTINENTAIS DAS FASES PRÉ­RIFT E RIFT DA SUB­BACIA DE ALAGOAS CENTRAL

CONTINENTAL SEQUENCIES OF THE PRE­RIFT AND RIFT PHASES OF THE CENTRAL ALAGOAS SUB­BASIN

Flávio Juarez Feijó (1992)

Adviser: Luiz José Tomazelli

Abstract

Ten third­order genetic stratigraphic sequences, bounded by flooding surfaces, were defined in the Central Alagoas Sub­Basin, Northeastern Brazil, based on well data, with some outcrop and seismic additional information. Two of the sequences can be assigned to a pre­rift stage, and the remaining eight sequences are related to the rift stage, which are split by the Pre­Aratu Unconformity. Those sedimentary rock packages were deposited between the Late Tithonian and the Early Aptian (150­120 m.a.), and depict almost all the preserved Central Alagoas Sub­Basin sedimentary fill. The studied facies allowed aluvial fan, braided fluvial, deltaic, evaporitic and lacustrine, including shelf and turbi-ditic depositional systems to be recognized. Their distribution is basically controlled by climatic constraints and tectonic setting. The sub­basin deepens northeastward, both through regional dip and normal faults, leaving only the older sequences in its southwestern side, where the younger ones have been removed by erosion. Conversely, only the younger sequences were sampled in the northeastern side of the sub­basin, since the older ones are at too great depths. It is possible to find stratigraphic traps for oil or gas in the more shaly parts of the sequences, but to detect them will demand more detailed mapping, with four - or fifth - order sequences being identified.

EVOLUÇÃO DAS SEQÜÊNCIAS MISTAS (SILICICLÁSTICAS E CARBONÁTICAS) SOB A INFLUÊNCIA DA HALOCINESE DURANTE O ALBO­APTIANO DA PLATAFORMA DE REGÊNCIA - BACIA DO ESPÍRITO SANTO

EVOLUTION OF THE MIXED SEQUENCES (SILICICLASTIC AND CARBONATIC) UNDER THE INFLUENCE OF HALOKINESIS DURING THE ALBIAN­APTIAN OF THE REGENCIA PLATFORM, ESPÍRITO SANTO BASIN

Cláudio Vinicius Tagliari (1993)

Adviser: Jorge Carlos Della Favera

Associated Adviser: Adali Ricardo Spadini

Abstract

The studied area is located within the center­eastern of the Regencia Platform and the nearshore zone.

The sedimentary rocks studied comprise an Albian­Aptian interval. This section was divided into three depositional sequences in terms of the modern concepts of Sequence Stratigraphy Paradigm. These Sequences were informally labeled, from the oldest to the youngest one, as Sequences "A", "B" and "C".

The Lowstand Systems Tract and the Transgressive Systems Tract of Sequence "A" were deposited under conditions of an epicontinental sea that provided the sedimentation of evaporites and carbonates in restricted environmental conditions. In this setting, the beds tend to be correlated laterally over long distances.

Between the phase that caracterized Sequence "A" Highstand Systems Tract deposition and Sequence "B" lower part, the area corresponding to Regencia Platform, once an epicontinental platform, evolved to a ramp platform. Sequences "B" and "C" are composed of alternated cycles composed of siliciclastics and carbonates. Eustatic changes, orbitally induced (excentricity and precession) in the scale of the Milankovitch Cycles (4th and 5th orders), are probably the main stratigraphic control of these alternations.

In Sequences "B" and "C", carbonates and siliciclastics occur simultaneously but with a tendency to mutual exclusion. Siliciclastics occupy nearshore zones, while carbonates tend to be displayed in more distal positions, existing an area of transition between both members.

Carbonate development is associated with the space available caused by the backstepping deposition of siliciclastics towards the source area, as a function of the eustatic rising. During sea level falling, or during the stillstand, or even during a slow rising when the sedimentary supply is sufficiently high to fill the accomodation space, siliciclastics prograde over the carbonate previously deposited. The dip of the detachtment surface (evaporitic section) of the listrics faults has changed (in the middle of Regencia Platform) during the Sequence "A" deposition. The tectonism responsible for this changing caused the movement of a great amount of halite to the lower declivity zone. The remobilization of this salt layer greatly affected thesedimentation during the upper part of Sequence "A" and troughout all over Sequence "B" and "C" sedimentation.

Salt sliding, perhaps associated with its dissolution, was the main factor of accomodation space generation in Regencia Platform, considering a third order scale.

Análise de Fácies e Estratigrafia Física do Arenito Lapa, Grupo Itararé, Bacia do Paraná, Brasil

Roberto Salvador Francisco D'Ávila (1999)

Adviser: Prof. Rodi Avila Medeiro
Commitee: Prof. Paulo Sergio Gomes Paim; Prof. Paul Edwin Potter; Prof. Luiz Jose Tomazelli

Palavras Chave: Grupo Itararé, Lapa, Bacia do Paraná, Turbidito, Estratigrafia de seqüências, Estratigrafia, Carbonífero, Permiano, Permocarbonífero

Resumo

O Arenito Lapa, uma unidade litoestratigráfica informal do Grupo Itararé, de idade westphaliana/stephaniana, é um corpo sinuoso canalizado, orientado na direção norte-sul, com mais de 50km de extensão e 800m de largura, aflorando como cristas alongadas de até 150m de altura na região entre as cidades de Lapa (PR) e Rio Negrinho (SC). Afloramentos do Arenito Lapa foram descritos e interpretados a partir da medição de seções por técnicas de sedimentologia e da estratigrafia física, associadas ao levantamento cintilométrico e coleta extensiva de amostras para datação. As encaixantes (seção pré-Lapa) são depósitos westphalianos correlacionáveis às formações Campo do Tenente e Lagoa Azul. Foram identificadas 14 fácies sedimentares no Arenito Lapa, entre arenitos, conglomerados e diamictitos, cujo agrupamento segundo os processos deposicionais comuns resultou em sete associações de fácies: fluxos gravitacionais, tempestades, marés, praia, fluvial canalizada, fluvial em lençol e de cheia fluvial. Com base nas relações laterais e verticais dessas associações de fácies foram caracterizados três sistemas deposicionais: o sistema marinho plataformal com fluxos gravitacionais (base do vale), o fluvial e o costeiro. Os depósitos do sistema fluvial, os mais comuns do Arenito Lapa, são compostos por sedimentos fluviais canalizados, fluviais em lençol e de cheia fluvial. Estas cheias foram detonadas possivelmente por rupturas de barragens de gelo. O sistema costeiro é constituído pela associação de depósitos de praia com depósitos de canais fluviais e de marés. O Arenito Lapa representa os depósitos de preenchimento de um vale inciso glacial. O vale foi preenchido durante uma transgressão devida a elevação do nível do mar relativo provocada pelo aumento da temperatura ao final de um ciclo glacial, ocasionando o derretimento e recuo das geleiras. Os sedimentos mais antigos do vale são depósitos marinhos representados por fácies de tempestade e marés com intercalação de fluxos gravitacionais turbulentos de alta energia. A ocorrência destes depósitos marinhos na base do vale sugere que a geleira estava aterrada no mar ao começar o recuo. Sobre estes depósitos ocorreu a progradação de sedimentos fluviais e costeiros enquanto se processava a transgressão. A seção pré-Lapa é representada por depósitos glaciomarinhos com fácies de rain-out, turbiditos distais e hemipelagitos, que constituem possivelmente parte do trato de Sistemas de Mar Alto de uma seqüência deposicional. As sucessões pré-Lapa e a do Arenito Lapa formam duas seqüências deposicionais de terceira ordem. Elas integram uma das seqüências de segunda ordem do Grupo Itararé, que é composto por três seqüências de segunda ordem, cada uma com duração média estimada de 10m.a.. O Arenito Lapa constitui parte do Trato de Sistemas Transgressivo de uma seqüência deposicional de terceira ordem (duração ~ 5m.a.). Estima-se que o Lapa tenha sido depositado em cerca de 1,25 milhões de anos. Internamente este arenito é constituído por cinco seqüências deposicionais de quarta ordem, com duração média de 250mil anos. O modelo conceitual da estratigrafia de seqüências proposto para esta região glaciada difere daqueles normalmente aplicados a bacias de margem passiva. A diferença principal decorre do elevado aporte e progradação sedimentar durante a transgressão numa região glaciada, enquanto nas bacias distantes do foco glacial a sedimentação é predominantemente fina e retrogradante. Um ciclo completo de variação relativa do nível do mar numa região glaciada envolveria cinco fases: 1) escavação do vale inciso glacial durante o máximo avanço do gelo (Trato de Sistemas de Mar Baixo), causando rebound negativo e subida do nível do mar relativo nas regiões marinhas em frente ao lençol de gelo. Deposição de tilitos, formação de pavimentos estriados e escavação extensiva do substrato nas áreas continentais; 2) melhoria climática e início do degelo (Trato de Sistemas Transgressivo), onde o elevado aporte sedimentar trazido pelas águas do degelo e o rebound positivo levam à progradação de sediment os fluviais e costeiros no interior dos vales, recobrindo fácies marinhas nas partes distais; 3) prosseguimento da deglaciação, transgressão marinha do vale, deposição de fácies glaciomarinhas ricas em clastos pingados (final do Trato de Sistemas Transgressivo); 4) máximo da deglaciação, depositando fácies glaciomarinhas com poucos clastos pingados (início do Trato de Sistemas de Mar Alto); 5) retomada da glaciação, avanço do gelo. O peso adicional do gelo aumenta a subsidência da bacia, o que, em associação ao aumento do aporte sedimentar, provoca a instabilização da enorme massa de sedimentos finos rapidamente depositados em períodos anteriores, criando um grande potencial para geração de fluxos de massa. Novamente aumenta o teor de clastos pingados nos sedimentos (glácio)marinhos.
A aplicação das técnicas de levantamento de seções da estratigrafia física associada a cintilometria e bioestratigrafia permitiu uma melhor correlação e resolução estratigráfica, levando à subdivisão dos depósitos do Grupo Itararé/Arenito Lapa em seqüências deposicionais de freqüência elevada, o que não seria obtido pelas utilização isolada das técnicas bioestratigráficas e biozonas ora disponíveis para o Paleozóico. Outros vales incisos glaciais foram reconhecidos em afloramentos, em poços de petróleo pela comparação das curvas de radiatividade natural dos afloramentos com os perfis de raios gama, e na escala da sísmica, apresentando geometria, assinatura e possança similares às do Arenito Lapa, o que sugere que a formação de vales incisos glaciais foi uma feição comum nesta bacia intracratônica. A análise regional revelou dois outros possíveis depósitos de preenchimento de vales incisos glaciais, similares ao Arenito Lapa, os Arenitos Pedra Alta e Espigão Branco, que marcam a base de seqüências deposicionais de terceira ordem. Depósitos com feições similares aparecem também nos poços de petróleo próximos da área e em seções sísmicas.

Facies Analysis and Physical Stratigraphy of Lapa Sandstone, Itararé Group, Paraná Basin, Brazil

Key Words: Itarare Group, Lapa, Paraná Basin, Turbidite, Sequence Stratigraphy, Carboniferous, Permian, Permocarboniferous

Abstract

The Lapa Sandstone, an informal stratigraphic unit of the Itararé Group, dated as westphalian/stephanian age, is a sinuous N-S oriented channelized body, measuring more than 50km in lenght and 800m in width. This sandstone crops out as elongated cliffs, up to 150m in height, in the region between Lapa (PR) and Rio Negrinho (SC) cities. Outcrops of the Lapa Sandstone have been described and interpreted using sedimentological and physical stratigraphy techniques, in association with a scintilometric survey and extensive sampling for paleontological dating. The surrounding rocks are westphalian deposits belonging to the Campo do Tenente and Lagoa Azul formations.
Fourteen sedimentary facies were identified, consisting of sandstones, conglomerates and diamictites. The grouping of these facies, according to their depositional processes, have resulted in seven facies associations: gravity flows, tidal and storm deposits, beach, and fluvial (sheet, channelized and fluvial flood deposits). Three depositional systems have been recognized, based on the lateral and vertical relationships of these facies associations: shelfal marine with gravity flows (valley's base), fluvial and coastal systems. The fluvial deposits, including channelized, sheet and flood facies associations, are the commonest in the Lapa sandstone. The floods are considered to be a result of the breaking of ice dammed lakes. Beach deposits associated with fluvial channel and tidal deposits constitutes the coastal system. The Lapa Sandstone is defined as a glacial incised valley filling deposit. The valley was probably filled during a transgression following the ice retreat and the subsequent rise of the relative sea level caused by rising temperatures after a glacial maximum. The oldest sediments in the valley are marine tidal and storm facies associated with turbulent high-energy gravity flows deposits. The occurrence of these facies in the valley bottom suggests that the glacier had its terminus grounded at the sea when the ice retreat started. Fluvial and coastal sediments have prograded over these older deposits.
The Itarare Group can be subdivided into three second order depositional sequences, averaging 10 millions years each. In the study area, one of these sequences was further subdivided into two higher frequency sequences: the Pre-Lapa and the Lapa Sandstone depositional sequences. Glaciomarine deposits with rain-out, distal turbidites, and hemipelagites facies comprises the pre-Lapa sequence.
The Lapa sandstone constitutes part of the Transgressive Systems Tract of a third order depositional sequence (ca. 5m.a. duration). The deposition of the Lapa sandstone is estimated to have ocurred during aproximatelly 1,25m.a. These sandstone is composed by at least five fourth order depositional sequences, each one deposited during ca. 250k.a.
The conceptual sequence-stratigraphic model proposed for this glaciated region differs from those generally used in passive margin basins, the main difference being the higher sedimentary supply and progradation that are interpreted to have occured during the transgression in this region, in contrast to the mainly retrogressive and fine-grained sedimentation in basins located far from the ice center. A complete cycle of relative sea-level variation would involve five phases: (1) incised valley excavation during the glacial maximum (Lowstand Systems Tract), causing subsidence and a relative sea-level rise at the marine regions in front of the ice sheet; lodgement tills, glacial striae and extensive substrate scouring occurs on shore; (2) beginning of the ice-melting due to warmer climate/temperature (Transgressive Systems Tract): positive rebound and high sediment meltwater discharge cause fluvial and coastal sediments progradation in the valley, covering older marine facies deposits; (3) following deglaciation, marine transgression of the valley, and deposition of glaciomarine dropstone-rich facies (Late Transgressive Systems Tract); (4) deglaciation maximum: dropstone-poor glaciomarine facies (Early Highstand Systems Tract); (5) return to glacial conditions with ice readvance, the additional ice weight enhances basin subsidence, as well the sedimentary supply, producin g the growing instability of the huge fine-grained mass deposited in previous phases, creating a high potential for gravity-flow deposits initiation; dropstone amount increases again. The application of physical stratigraphy techniques in association with cintilometric survey and extensive sampling for biostratigraphic analysis permitted a better correlation and higher stratigraphic resolution, and made possible the subdivision of the Itarare Group and Lapa Sandstone deposits into high frequency depositional sequences, unrecognizable by the biostratigraphic framework now available for this paleozoic deposits. The recognition of similar glacial incised valley fill deposits in the surrounding outcrops, well logs and seismic scales suggests that these features were commonly developed during the glaciation of this intracratonic basin. During the regional study two other possible glacial incised valley filling deposits, similar to the Lapa sandstone, were recognized: the Pedra Alta and Espigão Branco sandstones, interpreted as basal deposits of third order depositional sequences. Similar features were also identified in boreholes logs and seismic sections in the area.

Estudo de cicloestratigrafia nos depósitos Eopermianos do Grupo Itararé, Bacia do Paraná, nos estados de Santa Catarina e do Rio Grande do Sul, baseado em dados de testemunho e de perfis de raios gama

José Guilherme Rodrigues da Silva (2001)
Adviser: Nilo Chagas de Azambuja Filho
Committe: César Cainelli ; Clóvis Francisco Santos; Paulo Sérgio Gomes Paim

Resumo

O final da Glaciação Neopaleozóica está representado hoje no registro sedimentar da Bacia do Paraná pelas rochas do Grupo Itararé. No Estado do Rio Grande do Sul e no sudeste do Estado de Santa Catarina seus depósitos possuem idade eopermiana, datados desde o Asseliano até o Artinskiano. A partir de dados de testemunhos e de perfis de raios gama de dois poços, um em Santa Catarina (7-RL-04-SC) e outro no Rio Grande do Sul (IB-93-RS), perfurados para pesquisa de carvão pela CPRM (Companhia de Pesquisa de Recursos Minerais), foram feitas análises cicloestratigráficas com o intuito de determinar a existência e a natureza da possível ciclicidade induzida por fenômenos astronômicos presente nesses sedimentos glaciais (basicamente folhelhos e ritmitos). A distância entre as locações originais dos poços (cerca de 380 km) possibilitou testar a influência da indução astronômica em localidades distintas da bacia. Dois métodos de amostragem foram utilizados no estudo, de aco rdo com a escala dos dados e com a possível indução: os perfis de raios gama (191 m para o 7-RL-04-SC e 71 m para o IB-93-RS) foram digitalizados e amostrados em intervalos de 1 cm, com o intuito de testar a presença de indução pelos ciclos orbitais na escala de 20 mil a 400 mil anos, ou outros fenômenos indutores na escala de 3 mil a 10 mil anos, e os testemunhos foram escaneados nos intervalos com ritmitos, (1,2 m para o 7-RL-04-SC e 38 cm para o IB-93-RS) e transformados em dados em escala de cinza equiespaçados (0,2538 mm), objetivando a busca por ciclos anuais a milenares. A análise harmônica pela transformada rápida de Fourier demonstrou a presença de ciclicidade em ambas as escalas: ciclos orbitais, com períodos de cerca de 17 mil a 100 mil anos, foram caracterizados em perfil e ciclos solares, com períodos de cerca de 22 a 1000 anos, foram evidenciados nos testemunhos. Os tempos de acumulação calculados para o poço 7-RL-04-SC nas duas escalas mostraram um alto grau d e correlação (cerca de 9400 anos para o intervalo escaneado e aproximadamente 12600 para o mesmo intervalo nos dados do perfil), comprovando a eficiência dos métodos de obtenção dos dados e a utilidade da cicloestratigrafia como ferramenta de análise e refinamento cronoestratigráfico. Quanto às espessas seções de ritmitos, características do Grupo Itararé e presentes nos testemunhos, estas têm sido freqüentemente denominadas de varvitos ou referenciadas como semelhantes a varvitos na literatura. Porém os resultados mostraram que cada par de ritmitos foi depositado em períodos de vinte e dois anos, relacionados aos ciclos solares de Hale. A análise permitiu ainda o estudo das relações existentes entre várias variáveis, como a taxa e o tempo de acumulação, e a definição, na seção do poço 7-RL-04-SC, de seqüências deposicionais de terceira e de quarta ordem. Essas últimas são associadas à indução pelos ciclos orbitais de excentricidade e comparáveis aos períodos glaciais do Ple istoceno, sendo que as taxas de acumulação calculadas para os dados do poço, variando entre 5,2 a 9,3 cm/ka, são muito similares às taxas de acumulação do Pleistoceno. A análise também mostrou que a seção completa do Grupo Itararé no poço IB-93-RS corresponde apenas à cerca de meio ciclo de precessão (12342 anos). Como os dois fenômenos de indução astronômica detectados, os ciclos solares e os orbitais, afetam o clima de maneira global, certamente influenciaram a sedimentação em outros pontos da bacia.

Abstract

Cyclostratigraphy study in the early Permian deposits of Itararé group, Paraná basin, in the Santa Catarina and Rio Grande do Sul states, Brazil, using core and gamma ray log data.

The end of the Neopaleozoic Glaciation is represented today in the sedimentary record of Paraná Basin by the rocks of the Itararé Group. In the State of Rio Grande do Sul and in the southeast portion of the State of Santa Catarina this glacial deposits are Eopermian, ranging in age from Asselian to Artinskian. The existence and the nature of possible astronomic forcing of cyclicity in these sediments, basically shales and rhythmites, were studied in core and gamma ray log data from two wells drilled by CPRM (Companhia de Pesquisa de Recursos Minerais) to coal research, one in Santa Catarina (7-RL-04-SC) and the other in Rio Grande do Sul (IB-93-RS). The distance between the original location of the cores (about 380 km) made it possible to test the astronomic forcing in this glacial deposits in different locations of the basin. Two methods of data sampling were used, according to data scale and the possible forcing: the gamma ray logs (191 m for 7-RL-04-SC an d 71 m for IB-93-RS) were digitized and sampled at 1 cm intervals, in order to test the presence of orbital forcing at scales of 20,000 to 400,000 years or other forcing phenomena in scales of 3,000 to 10,000 years, and the cores were scanned in the intervals with rhythmites (1,2 m for 7-RL-04-SC and 38 cm for IB-93-RS) and transformed in gray scale data sampled equally (0,2538 mm), in order to search for annual to millenarian cycles. The harmonic analysis by the fast Fourier transform showed cyclicity in both scales: orbital cycles ranging from about 17,000 to 100,000 years were discovered in the log data, and solar cycles ranging from 22 to about 1,000 years were discovered in the core data. The accumulation time calculated for the well 7-RL-04-SC in log and core data (about 9,400 years for the scanned interval and about 12,600 years for the same interval in log data) showed a were very high correlation, proving the efficiency of the methodology and the usefulness of cyclo stratigraphy as a chronostratigraphic analysis and refining tool. The thick rhythmic sections of the Itararé Group present in the cores studied have been frequently mentioned in literature as varvites or varve-like deposits. The results showed that each pair of rhythmites were deposited during a 22 years period related to the Hale solar cycles. The analysis also permitted the study of the relations between several variables, as accumulation time and accumulation rate, and the definition in 7-RL-04-SC well section of third and fourth order depositional sequences. These fourth order sequences are related to the eccentricity orbital forcing, been similar to the Pleistocene glacial cycles, and the accumulation rates calculated for the well data, ranging from 5,2 to 9,3 cm/ka, are very similar to the Pleistocene accumulation rates. The analysis also showed that the complete sedimentary record of the Itararé Group for the well IB-93-RS corresponds to about half precession cycle (1 2,342 years). As both astronomic forcing phenomena detected, the solar and the orbital cycles, affect climate on a global scale, certainly their influence on sedimentation occurred in other locations of the basin.

Bioestratigrafia de Nanofósseis Calcários e Estratigrafia de Isótopos (C e O) do talude médio, Quaternário, porção N da Bacia de Campos, ES

Lucio Riogi Tokutake (2005) - ltokutake@terra.com.br
Adviser: Valesca Brasil Lemos - Co-adviser: Felipe Antonio de Lima Toledo
Committe: Luiz José Tomazelli; Rogério Loureiro Antunes; Karen Badaraco Costa

Palavras Chave: Estratigrafia; Quaternário; Bacia de Campos; Bioestratigrafia; Nanofósseis calcários; Isótopos Estáveis; Espírito Santo

Resumo

A Bacia de Campos, em sua porção norte, na parte sul do território oceânico do Estado do Espírito Santo é uma área ainda pouco estudada e conhecida, principalmente o Quaternário em águas profundas. Foram escolhidos dois testemunhos, do talude médio na área, nos quais foram realizadas amostragens para Bioestratigrafia de nanofósseis calcários e Isótopos Estáveis (Carbono e Oxigênio).
Os resultados de nanofósseis calcários mostraram que a base do bio-evento de acme de Emiliania huxleyi deve ser localizado em 73 mil anos BP na área, ao contrário do que foi proposto anteriormente. Mostram também uma predominância absoluta de dois taxa: Emiliania huxleyi e Gephyrocapsa spp.
A Estratigrafia de Isótopos de Oxigênio mostrou uma excelente correlação com os modelos, permitindo um bom balizamento com os estágios isotópicos de oxigênio existentes. A base do bio-evento de acme de Emiliania huxleyi foi posicionada na passagem entre os estágios isotópicos 4 e 5. A correlação da abundância relativa de E. huxleyi e de 18O mostra uma boa correlação, indicando influência do paleotemperatura na abundância deste taxa.
Os dados de Estratigrafia de Isótopos de Carbono mostraram uma boa correlação com as variações de abundância do gênero Gephyrocapsa. Tais dados indicam variação de disponibilidade de nutrientes, concluindo-se que ocorreram períodos de eutrofia e de oligotrofia na área, devido ao aporte de material continental. Estes dados associados ao Sistema Turbidítico Itabapoana, atualmente inativo, permitem supor que este sistema alimentou a área com nutrientes de origem continental no passado.
Pela limitação da área de estudo, não foi possível comprovar se o relativo atraso do bio-evento é regional ou apenas efeito local do aporte de material continental pelo Sistema Turbidíditico Itabapoana, que enriqueceu de nutrientes, que permitiu a continuidade da abundância do gênero Gephyrocapsa.

Biostratigraphy of Clacareous Nanofossils and Stratigraphy of Isotopes (C e O) of the medium continental slope, Quaternary, northern part of Campos Basin, State of Espírito Santo

KeyWords: Stratigraphy; Quaternary; Campos Basin; Biostratigraphy; Calcareous nannofossils ; Stable isotops; Espirito Santo state

Abstract

The Campos Basin north portion, in the south coast of Espírito Santo state is almost unknown and was not studied enough, specialy the Quaternary in deep water. It was chosen two cores middle slope cores in this area. Samples were collected in these cores for Calcareous Nannofossils Biostratigraphy and Stable Isotops (Carbon and Oxygen).
Calcareous Nannofossils results shows that the Emiliania huxleyi acme base is located at 73 kyr BP, instead of what was estabilished previously in tropical region. Calcareous Nannofossils data shows an absolut predominance of Emiliania huxleyi and Gephyrocapsa spp.
Stable Isotops reveals an excelent correlation with models, allowing a good comparison with the oxygen isotopic stages. The E. huxleyi acme base is located at the limit between isotopic stages 4 and 5. The correlation between E. Huxleyi relative abundance and 18O, indicating paleotemperature affected the taxa abunndance.
The Carbon Stable Isotopic data shows a good correlation between abundance variations of the genus Gephyrocapsa. Both indicates variation of nutrients availiability. It is possible to conclude that occurred periods of eutrophy and oligotrophy in that area, caused by the aport of continental nutrient rich sediment. It is possible to suppose that Itabapoana Turbiditic System, which is now inactive, feeded the area with continental nutrients in the past.
As this study is limmited in area, it was not possible to confirm is the the Emiliania huxleyi acme base delay is a regional event, or if is a local effect of continental nutrients carried by the Itabapoana Turbiditic System, wich allowed the Gephyrocapsa genus abundance had continued for a while in this area.