Journal of Petroleum Geology, Vol.2, No.4, pp. 389-410, 1980

©Copyright 2000 Scientific Press, Ltd.

TECTONIC CONTROL AND PETROLEUM GEOLOGY OF THE PALEOZOIC CLASTICS OF THE MARANHAO BASIN, BRAZIL

Albert V. Carozzi*

*Professor of Geology, University of Illinois at Urbana-Champaign. Urbana. Illinois, 61801, International Oil Exploration Consultant,USA, and International Oil Exploration Consultant.

Abstract

Selected paleoenvironmental maps of the Maranhão Basin from Silurian to Eo-Carboniferous are analyzed in terms of their source rock and reservoir potentials. These maps combine petrographic data with the distribution of clay mineral assemblages, palynofacies, trace-metals, organic carbon and boron. Two depositional models are recognized. The first one, which lasted from Silurian to Eo-Carboniferous, is a model of coalescent deltas in which delta systems (with seven subenvironments) are separated by interdeltaic areas (with five subenvironments). The second model, limited to the Late Devonian, shows a continental ice sheet interfering with a system of coalescent deltas and generating mixed glacio-deltaic sediments.