Petrology of continental pyroclastic and epiclastic sequences in the Chubut Group (Cretaceous): Los Altares- Las Plumas area, Chubut, Patagonia Argentina

摘要

The volcaniclastic successions of the Cerro Barcino Formation (Chubut Group), of Aptian - Cenomanian age, crop out on both margins of the Chubut River with a thickness of 200 m. The Middle Member Cerro Castano (syneruptive, 90 m) and the Upper Member, Las Plumas (lintereruptive, 110 m) are described on the basis of photogeological mapping, sections, and mineralogical, petrographical and geochemcial analysis. Paleocurrents are directed to the northeast (Cerro Castano) or north (Las Plumas).