ABSTRACT: The Triassic Jurua Orogeny and Tectono-Sedimentary Evolution of Peruvian Oriente Basin: Exploratory Implications

BARROS, M. C., and E. P. CARNEIRO, Petrobras International S.A., Rio de Janeiro, Brazil

The tectono-sedimentary evolution of the Peruvian Oriente and the Brazilian Acre and Solimoes basins can be represented by two systems: Pre-Andean and Andean. The first system consists of three MSIS Paleozoic cycles ranging from Ordovician to Middle Permian ages, deposited over a broad and gentle platform, where source and reservoir rocks were laid down. The Andean System is composed by an IF and three MSIS cycles ranging in age from Neo-Permian to Neo-Tertiary.

The IF phase resulted in widespread northwest-southeast-oriented grabens (Andean trend), during Neo-Permian to Eocene-Triassic times, when a huge crustal rearrangement occurred along the northwestern border of the South American plate, related to the beginning of the Andean subduction zone. After this extensional episode, a strong inversion tectonic took place herein named the "Jurua orogeny." This diastrophic event constitutes the first orogeny of the Andean System, and its effects reached up to the Solimoes basin, where gas and light oil accumulations have been found in trends related to this event. The Triassic orogeny originated the Proto-Andean chain and the Andean foredeep, which encompasses the Mesozoic and Cenozoic MSIS cycles. Up to now, the exploratory efforts in the Oriente basin have been conducted only in the oil-bearing Cretaceous section, while the oil potential of the pre-Cretaceous interval has not yet been properly evaluated.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)