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História térmica do maciço alcalino de Poços de Caldas (SP/ MG) e adjacências através da análise de datação por traços de fissão em apatitas

2005; Sociedade Brasileira de Geologia; Volume: 35; Issue: 3 Linguagem: Inglês

10.5327/rbg.v35i3.1175

2317-4889

Ana Olívia Barufi Franco, Peter Christian Hackspacher, Daniel Françoso de Godoy, Luis Felipe Brandini Ribeiro, S. Guedes,

Geochemistry and Geologic Mapping

The South American Platform in southeastern Brazil records a long history of tectonicmagmatic and uplift events, which resulted from the opening of the South Atlantic Ocean, Cretaceous reactivation and epirogeneic processes. Specific manifestations include the basic magmatism of the Serra Geral Formation of the Parana Basin and alkaline magmatism of Pocos de Caldas – Cabo Frio Lineament, as well as the uplift of the Serra da Mantiqueira and Serra do Mar mountain ranges. Thermotectonic and geochronological studies using the K-Ar method and apatite fission track analysis in samples of the Pocos de Caldas alkaline massif show an initial evolution beginning 89 Ma related to a tectonic uplift, interpreted as related to the intrusion’s doming. This was followed by an important episode of rapid cooling related to the formation of the massif. At the same time, the mountains that surround the massif record heating events in response to the alkaline intrusion, between 70 and 50 Ma. Periods of slow uplift, probably related to the South American Erosion Cycle (between 50 and 30 Ma) and Velhas Erosion Cycle (from 25 Ma), indicate a strong manifestation of denudation in this area.