Abstract

Kinematic analysis of fault slip data for stress determination was carried out on Late Miocene to Quaternary rocks from the fore arc and intra-arc regions of the Chilean Andes, between 33°and 46°south latitudes. Studies of Neogene and Quaternary infilling (the Central Depression), as well as plutonic rocks of the North Patagonian Batholith along the Liquine-Ofqui Fault Zone, have revealed various compressional and/or transpressional states of stress. In the Pliocene, the maximum compressional stress (σ1) was generally oriented east-west. During the Quaternary, the deformation was partitioned into two coeval distinctive states of stress. In the fore arc zone, the state of stress was compressional, with σ1 oriented in a N-S to NNE-SSW direction. In the intra-arc zone the state of stress was transpressional with σ1 striking NE-SW. Along the coast, in one site (37°30'S) the Quaternary strain deformation is extensional, with an E-W direction, which can be explained by a co-seismic crustal bending readjustment. Kinematic analysis of fault slip data for stress determination was carried out on Late Miocene to Quaternary rocks from the fore arc and intra-arc regions of the Chilean Andes, between 33° and 46° south latitudes. Studies of Neogene and Quaternary infilling (the Central Depression), as well as plutonic rocks of the North Patagonian Batholith along the Liquine-Ofqui Fault Zone, have revealed various compressional and/or transpressional states of stress. In the Pliocene, the maximum compressional stress (σ1) was generally oriented east-west. During the Quaternary, the deformation was partitioned into two coeval distinctive states of stress. In the fore arc zone, the state of stress was compressional, with σ1 oriented in a N-S to NNE-SSW direction. In the intra-arc zone the state of stress was transpressional with σ1 striking NE-SW. Along the coast, in one site (37°30 minutes S) the Quaternary strain deformation is extensional, with an E-W direction, which can be explained by a co-seismic crustal bending readjustment.