Portal de Periódicos da CAPES

Artigo Produção Nacional

BIBTEX RIS

CIMENTAÇÃO HIDROTERMAL EM DEPÓSITOS SEDIMENTARES PALEOGÊNICOS DO RIFT CONTINENTAL DO SUDESTE DO BRASIL: MINERALOGIA E RELAÇÕES TECTÔNICAS

2001; Sociedade Brasileira de Geologia; Volume: 31; Issue: 2 Linguagem: Inglês

10.5327/rbg.v31i2.937

2317-4889

Lucy Gomes Sant’Anna, Cláudio Riccomini,

Paleontology and Stratigraphy of Fossils

Paleogene sedimentary deposits of the Continental Rift of Southeastern Brazil (CRSB) locally show hydrothermal cementation. SEM/EDS and XRD analyses revealed the presence of quartz and opal- CT cements respectively in the Itaborai and Macacu formations (Itaborai Basin) and mainly kaolinite and opal-CT in the Resende Formation (Sao Paulo and Taubate basins). The cementation was penecontemporaneous to the sedimentation, during the main phase of development of the CRSB in the Eocene, and controlled by brittle tectonic structures and sediments with high porosity and permeability. At that epoch, the regional geological setting encompassed the favourable conditions for circulation and cementation by hydrothermal solutions in porous media of the ritf basins, such as: 1) stress-field with NNW-SSE direction of extension, opening NE-trending faults in the basement and in the sedimentary cover; 2) high regional thermal flow; and 3) magmatism with the extrusion of ankaramitic lavas. In this context, the hydrothermal solutions, which percolated the sediments, could derived from connate, meteoric and/or magmatic waters.