Transpresión dextral y partición de la deformación en la Zona de Falla Liquiñe-Ofqui, Aisén, Chile (44-45ºS)

Abstract

Dextral transpression and deformation partitioning in the Liquiñe-Ofqui Fault Zone, Aisén, Chile (44-45ºS). The segment of the North Patagonian Batholith between 44 and 45ºS is affected by locally intense ductile and brittle deformation spatially associated with the Liquiñe-Ofqui Fault Zone. The fault zone, at the regional scale, is representad by a north to northeast-trending lineament (Puyuguapi Canal) which makes up part of a crustal-scale strike-slip duplex in the Patagonian Cordillera as suggested by previous studies. Late Miocene-Pliocene ductile deformation is documented by centimetric-to metric-wide tabular mylonite zones with subvertical foliation and subvertical, oblique, and subhorizontally plunging lineations. Dextral transpressional deformation predominates along north to northeast-trending shear zones, whereas dextral transtensional deformation is documented along east to northeast trending shear zones. Brittle deformation, representad by decametric faults with striae and good kinematic indicators, is widely exposed and overprints the early ductile fabric. The post-Late Miocene brittle deformation is compatible with dextral transpressional and transtensional kinematics along north-northeast and east-northeast fault zones, respectively. A kinematic analysis of contemporaneous strike-slip, oblique-slip and contractional deformation on brittle faults and shear zones at 44ºS, suggests some degree of deformation partitioning of bulk dextral transpressional deformation in the Liquiñe-Ofqui Fault Zone.