Argilominerais Do Paleolago Tremembé E Sistemas Deposicionais Relacionados (Paleógeno, Rift Continental Do Sudeste Do Brasil)

Abstract

Study of the clay mineral content of Oligocene lacustrine sediments of the Tremembé Formation and laterally correlative deposits of a marginal system of distal alluvial fans of the Resende Formation has furnished important indicators of paleoenvironmental and paleoclimatic conditions during the génesis of these minerais within the context of the Paleogene evolution of the Continental Rift of Southeastern Brazil. X-ray diffraction and scanning electron microscopy revealed clay minerais of the smectite and kaolinite groups and, to a much lesser extent, members of the mica and chlorite groups. Detrital clay minerais in the Tremembé and Resende Formations are mainly represented by smectites, generated under generally arid conditions probably during the Eocene. Ancient soils developed upon Precambrian basement rocks acted as remarkable source-areas for the smectites, although the conditions for their genesis are still unresolved. Eodiagenetic halloysite in deltaic sandstones of the Tremembé Formation was derived by decomposition of feldspar and is indicative of pluvial seasonality during sedimentation. Worm-like kaolinite was formed during a later diagenetic stage, without the influence of the depositional environment. The presence of kaolinite in the meandering fluvial system of the São Paulo Formation suggests a significam climatic change to humid conditions during the Late Oligocene. It appears, therefore, that the paleoclimatic and paleoenvironmental changes inferred from the clay mineralogy of the sediments studied here are in general accord with the pattern of global changes for the Paleogene as deduced from other geological and paleoceanographic evidence.

The Paleocene travertine system of the Itaboraí basin, Southeastern Brazil

“…1 and 2), is a small half-graben, 1.5 km long and 0.5 km wide, in the eastern part of the continental rift of southeastern Brazil (CRSB) (Riccomini, 1989;Riccomini et al, 1996). The rift, of Cenozoic age, is an ENE-trending, narrow, elongate trough, approximately 1000 km long, that stretches from Curitiba (Paraná) in the WSW to Barra de São João (Rio de Janeiro) in the ENE (Fig.…”

Aplicação De Modelagem Geoestatística Por Krigagem Para Mapeamento Do Relevo Exposto E Do Paleo-Relevo Sotoposto À Bacia Sedimentar De Curitiba (Pr)

“…A concordância com uma gênese tectônica sincrônica, ou ao menos tardia, porém partícipe do mesmo contexto de sedimentação das bacias de São Paulo (SP), Taubaté (SP), Volta Redonda (RJ), Resende (RJ) e Itaboraí (RJ) é unânime, conforme Archela (1989Archela ( , 1990, Salvador (1994), Salamuni (1998), Riccomini et al (1996), Riccomini et al (2004), Archela (2004Archela ( , 2006, Salamuni et al (2003), Archela & Coimbra (2006), Archela & Yamamoto (2007, 2008a, 2008b, 2008c.…”

A reassessment of bunodont metatherians from the Paleogene of Itaboraí (Brazil): systematics and age of the Itaboraian SALMA

“…The basin is a small half-graben, 1.5 km long and 0.5 km wide, in the eastern part of the Continental Rift of Southeastern Brazil (CRSB) (Riccomini, 1989;Riccomini et al, 1996). The rift, Cenozoic in age, has an ENE-trending, narrow, elongate trough, approximately 1000 km long that stretches from Curitiba (Parana State) in the WSW to Barra de São João (Rio de Janeiro State) in the ENE.…”