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Exhumation of high‐pressure granulites of the Guaxupé Complex, southeastern Brazil
Author(s) -
Del Lama E. A.,
Zanardo A.,
Oliveira M. A. F.,
Morales N.
Publication year - 2000
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.859
Subject(s) - granulite , terrane , geology , geochemistry , kyanite , metamorphic rock , shear zone , craton , precambrian , facies , petrology , tectonics , metamorphism , gneiss , seismology , geomorphology , structural basin
This paper describes tectonic and metamorphic features of Precambrian rocks from the Guaxupé Complex and Varginha Shear Zone (VSZ) near the city of Guaxupé in the southern part of the São Francisco Craton, southeastern Brazil. The VSZ separates the metasediments of Araxá Group to the north from the granulites of Guaxupé Complex to the south. The sinistral transcurrent VSZ crosses the entire area striking approximately E–W, bending towards SE in the eastern part. Because of this bend, transpressional movement occurred, facilitating the exhumation of the garnet‐rich rocks of the deepest exposed part of the granulite‐facies terrane. In the garnet granulites the highest pressure–temperature conditions recorded are approximately 1040°C and 14.4 kbar. The rocks underwent decompression from 14.0 kbar to 8.0 kbar, cooling from 980°C to 710°C, the retrograde path following the boundary between the kyanite and sillimanite stability fields. This interval is interpreted to record the uplift of the lower crustal granulite‐facies terrane and re‐equilibration during magmatic intrusions. For the felsic granulites an interval of 700–810°C and 8.0–11.5 kbar was attained, also pointing to regional decompression. The granulites of the Guaxupé Complex comprise a medium‐ to high‐pressure lower‐crustal terrane, with local occurrences of higher‐pressure garnet‐rich gneisses, which were uplifted along a transpressional segment of the VSZ. Copyright © 2000 John Wiley & Sons, Ltd.