--> Abstract: Cenozoic Inversion of Permo-Triassic Rift in the Central Andes, Southern Peru, by Nicholas Perez; #90199 (2014)

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Cenozoic Inversion of Permo-Triassic Rift in the Central Andes, Southern Peru

Nicholas Perez
Jackson School of Geosciences/Geology, University of Texas at Austin, Austin, TX, USA
[email protected]


This study aims to constrain the timing and kinematics of pre-existing normal fault inversion in the Eastern Cordillera of southern Peru during Cenozoic Andean shortening. I will conduct apatite (U-Th)/He and fission track thermochronological analyses of multiple samples across two major structures with poorly constrained, multiphase deformational histories. The eastern structure is defined by coarse-grained deposits of the Permo-Triassic Mitu Group, a proposed synrift unit, and a linear belt of plutons intruded during proposed rifting. This spatial collocation of plutons and clastic fill suggests that their genesis was influenced by pre-Andean extension. The western structure, the Ayaviri backthrust, defines the structural border between the Eastern Cordillera and Altiplano. The presence of synrift Mitu Group deposits in only the hanging wall suggests that the structure originated as a normal fault. However, Oligocene growth strata along the fault confirm later reactivation as a thrust fault. Understanding how pre-existing structures are selectively reactivated during later shortening has implications for the evolution of orogens, fold-thrust belts and deformation propagation. This study also impacts the expanding petroleum exploration in southern Peru, where the Camisea gas fields of the Ucayali basin are most notable containing roughly 13.4 TCF gas. We will determine whether inversion along pre-existing structures occurred in a predictable systematic way or involved an irregular, out-of-sequence pattern of deformation. The results will improve predictions of the potential for reservoirs breached by out-of-sequence inversion, the timing of hydrocarbon genesis, and the creation of fluid migration pathways.

AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects