The Paleozoic Source Rock of NW Gondwana

摘要

During the Paleozoic, South America and Africa was part of the same continent, the Gondwana. The land mass was close to the south pole for a while and then migrated northward after the Carboniferous. Due to this common past geological setting, in both areas the Paleozoic formation have numerous similarities. The hot shale of north Africa, Silurian and Devonian in age are well known, and lead to large reserves in Algeria and Libya among others. The synthesis of the south American Paleozoic sources rock presented in this paper shows at the opposite that the richer organic shales are Carboniferous and Permian in age in South America. Silurian and Devonian source rocks exist, are sometime rather thick but never very rich (TOC ~2%, initial HI around 500). At the opposite the Lower Carboniferous of the Madre de Dios basins (Peru and Bolivia) and the Permian of the South Peru, North Bolivia and Parana in Brazil are the best Paleozoic SR of SA, with initial S2 up to 80 mg HC/g. Central South America therefore differs from the general trend of the compilation of the source rock richness, worldwide, as in North Africa, Silurian and Devonian show the best values.