Pablo E. Kraemer1, Adolfo Weiner2, P. Alvarez3
(1) Pecom Energia S. A, Neuquen, Argentina
(2) Pecom Energia S.A
(3) Pecom Energia S.A, Neuquen, Argentina
ABSTRACT: Tectonostratigraphic Framework of a Transtensional Forearc Basin. The Tumbes Basin of Northwestern Perú
The goal of this work is to present the tectonostratigraphic analysis of the offshore Tumbes basin, located on the western coast of Perú. The tectonic evolution of the basin has been controlled by plate convergence kinematics during the Cenozoic. Normal faults have a sigmoidal shape with an "echelon" arrangement, suggesting a right - lateral strike slip deformation.
The Cenozoic deposits comprise at least seven stratigraphic units of Oligocene to Pleistocene ages with a total thickness of more than 9000 m of sediments. These deposits rest unconformably above a Paleozoic basement. During the Oligocene to Early Miocene, deltaic, littoral and marine rocks were deposited in a narrow and unstable platform open to the NW.
A Mid - Miocene relative sea level fall produced a regional erosive unconformity that carved a complex morphology of incised valleys and hills. Late Miocene sediments were deposited during a relative sea level rise, until the paleotopography was completely buried. During the Pliocene a period of normal listric faulting and syntectonic sedimentation began. Normal faulting remained active during the Pleistocene and are still active as is evidenced by the recent deformation of sea bottom sediments.
This highly subsiding and narrow offshore basin, has an active hydrocarbon system. Several hydrocarbon accumulations have been found. The main source rock is the Heath Fm., and the trap types include rollover folds, tilted blocks and stratigraphic traps.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado