A Formação Marizal (Aptiano) na Bacia do Tucano (BA): contribuições à análise da arquitetura de depósitos fluviais e implicações paleobiogeográficas

Abstract

2014Autorizo a reprodução e divulgação total ou parcial deste trabalho, por qualquer meio convencional ou eletrônico, para fins de estudo e pesquisa, desde que citada a fonte. Emphasis is placed on the distinction between laterally equivalent deposits of channel fill and bars, given the recently recognized difficulty in distinguishing these elements, based on sedimentological data, in active depositional systems. In this way, the study of a selected are of the Banzaê Member enabled, through a quantitative approach considering the scale of architectural elements and cross-sets as well as paleohydraulic constraints, the recognition and individualization of deposits attributed to the fluvial geomorphological dynamics, such as unit bars, abandoned channel fills and channel belt successions bounded by avulsion surfaces.

Ground Penetrating Radar investigation of depositional architecture: the São Sebastião and Marizal formations in the Cretaceous Tucano Basin (Northeastern Brazil)

“…Composition of the siliciclastic rocks of the Marizal Formation is notably less mature than the São Sebastião Formation, with sandstone tending to be richer in feldspar and lithic fragments, which is also reflected in the richer variety of lithotypes found in the conglomerates of the Marizal Formation in comparison to the quartz rich conglomerates of the São Sebastião Formation (Freitas 2014.…”

“…This outcrop is found near the locality of Raso, at the South Tucano sub-basin, and is positioned in the Marizal Formation, with its fine-grained sandstone deposits interpreted as wave dominated coastal deposits by Freitas (2014). The medium-to large-scale geometry of the deposits is assessable at the outcrop, which is dominated by sandstone with low-angle cross-stratification, planar-bedding, and cross-laminated sandstone.…”

“…The base of the Marizal Formation records a large scale river, bearing sandstone deposits with large-scale inclined cross-sets, with subordinate mudstone and heterolithic beds (Freitas, 2014, which is covered by a marine incursion, represented by mudstone and heterolithic beds, with renown fossil assemblage (Almeida Filho et al, 2002;Reis et al, 2007;AlvaradoOrtega & Brito, 2010;Amaral & Brito, 2012). The upper part of the Marizal Formation records unconnected fluvial channel deposits isolated by proximal and distal floodplain deposits, with the larger channel deposits being similar to the sandstone deposits found at the base of the succession (Freitas 2014).…”

“…1), which were the subject of previous studies regarding the sedimentology and architecture of the deposits (Figueiredo 2013, Freitas 2014, Carrera 2015, so that the direct comparison to the GPR data were possible.…”

“…The target study area includes outcrops of the São Sebastião and Marizal formations, Barremian and Aptian (respectively) of the Tucano Basin, Northeastern Brazil, which were previously studied in regard to the depositional architecture of the deposits (Figueiredo 2013, Freitas 2014, Carrera 2015. The quality of the exposures and the existence of previous sedimentological studies make the area an ideal target for studies regarding the applicability of geophysical surveys to the investigation of fluvial depositional architecture in sedimentary rocks, with implications for hydrocarbon reservoir analogue studies (Tatum & Francke 2012).…”