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Tassinari, C.C.G.; Kawashita, K.; Schmuss, R. van; Taylor, P.N.
Sociedade Brasileira de Geologia, Sao Paulo, SP (Brazil)1988
Sociedade Brasileira de Geologia, Sao Paulo, SP (Brazil)1988
AbstractAbstract
[en] Rb-Sr, Pb-Pb and U-Pb geochronologic studies carried out on precambrian rocks from the southeastern Sao Paulo state suggest a Complex geologic evolution during the Archean and Proterozoic times. This region is divided in five differents allochthonous terranes named Itapira-Amparo, Piracaiba-Jundiai, Sao Roque, Embu and Costeiro, separated by thrust and strike-slip faults. The Itapira-Amparo domain has a original history dating back to 3.4 Ga. and since 2.6 to 2.5 Ga. and 2.2 to 1.9 Ga. metamorphic rockformation episode occurred involving both mantle-derived magmas and recycled material. Supracrustal sequences developed around 1.4 Ga. The domain was locally reworked in 0.8 - 0.65 Ga. In the Piracaia-Jundiai the main rock-formation event occurred at 1.4 Ga., but this domian was affected by strong granization and migmatization episodes during the period 1.1 - 0.6 Ga. The third terrain is characterized by the Sao Roque metavolcanossedimentary sequence developed during the time period 1.8 - 0.7 Ga., and comprising two metamorphic superimposed events (1.4 and 0.8 - 0.7 Ga.). the post-tectonics granites ranging in ages from 0.7 to 0.55 Ga. Within the Embu terrain ages of 2.5, 1.4 and 0,75 Ga. were obtained for the metamorphic terrain, with post-tectonic activities around 650 Ma. In the Costeiro domain all the metamorphic rocks developed in late-Proterozoic time, with syntectonic phase around 650 Ma
[pt]
Apresenta-se um estudo geocronologico de Rb-Sr, Pb-Pb e U-Pb feito nas rochas pre-cambrianas do sudeste de Sao Paulo. Este estudo sugere uma evolucao do complexo geologico durante os tempos Arqueanos e ProterozoicoOriginal Title
As idades das rochas e dos eventos metamorficos da regiao sudeste do estado de Sao Paulo
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1988; 16 p; 35. Brazilian Congress of Geology; Belem, PA (Brazil); 6-13 Nov 1988
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Miscellaneous
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Conference
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