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The Niquelandia Mafic-Ultramafic Complex, Goias, Brazil: a contribution to the ophiolite × stratiform controversy based on new geological and structural data 

Ferreira Filho C.F. 
Nilson A.A.
Naldrett A.J. 

Precambrian Research(1992),57(125):125-143.
Key words: ultramafic rock; deformation; metamorphism; mafic rock; igneous layering; Brazil; Goias; Niquelandia. 

Abstract

The results of a geological/structural mapping in a slice of the Niquelandia layered Mafic-Ultramafic Complex are presented. The complex stratigraphy is described. The most important tectonic feature all across the complex is the pervasive presence of westward dipping NS-N10E ductile shear zones with well developed tectonic foliation parallel with the primary bedding. The metamorphic paragenesis within the deformed zones progressively change from hypersthene-granulite facies in the basal and central units, to hornblende-granulite facies, and amphibolite facies in the upper unit. The tectonic features post-date the primary late-magmatic features what indicate that the tectonic event is not closely related with the emplacement of the Niquelandia Complex. The Niquelandia Complex is now considered as a single, major stratiform, mafic-ultramafic complex which subsequently underwent tectonism with associated high-grade metamorphism.