期刊
BRAZILIAN JOURNAL OF GEOLOGY
卷 46, 期 4, 页码 547-566出版社
SOC BRASILEIRA GEOLOGIA
DOI: 10.1590/2317-4889201620160034
关键词
structural geology; geochronology; Socorro-Guaxupc nappe; Embu terrane
资金
- Brazilian National Counsel of Technological and Scientific Development (CNPq)
- Brazilian Geological Survey (CPRM)
- Research Support Foundation of the State of Rio de Janeiro (FAPERJ)
The study area is localized in the Socorro nappe, part of the southern Brasilia belt, with a minor part in the Embu terrane, part of the central Ribeira belt. Three phases of deformation were detected, Dn-1, Dn and Dn+ 1. Sn-1 seems to be generally transposed into Sn, but in the northwestern part it is well preserved, dipping about 60 degrees to W and SW, with a stretching and/or mineral lineation plunging down dip. The main foliation in most of the area is Sn, dipping about 70 degrees to SSE. Dn folds are tight to isoclinal, with axes that plunge about 40 degrees to SW. Quartz-feldspathic segregation veins are folded by Dn. The structures related to Dn-1 and Dn are cut and modified by four important shear zones ascribed to deformation phase Dn+ 1. Two samples of a granite that is elongated along the Caxambu shear zone, and also cut by it, were dated. One yielded a crystallization age of 575 +/- 5 Ma, and the other one, from the shear zone, an age of 567 +/- 8 Ma, interpreted either as representing the age of movement along the Caxambu shear zone, or as metamorphic growth.
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