Deciphering the sub-ice basement architecture of the Rennick-Aviator fault zone: insight from outcrop scale fracture analysis.

The northern termination of the Transantarctic Mts in North Victoria Land is characterized by a complex architecture deriving from long-lived tectonic activity along major crustal shear zones that have been reactivated several times until Recent. These are both first-order faults, which separate the Wilson, Bowers and Robertson Bay crustal blocks, and second-order faults which cut through homogeneous lithotectonic units. Rennick Graben Fault (RGF) system and Aviator Fault (AF) represent a NW-SE shear corridor with along-strike length of about 400 km that connects to the kinematics of the fracture zones in the Southern Ocean (between Australia and East-Antarctica) and to the extensional tectonics in the Ross Sea embayment. In this contribution we present the analyses of structural data measured in the fault corridor of the RGF and AF to highlight i) the geometry/link of their connection, and ii) their Meso-Cenozoic poly-phased tectonic activity. Brittle deformation measured in the field includes faults with the associated kinematic indicators, fracture attitude, dimension (H) and spacing (S). This deformation involves rocks with ages ranging from Lower Paleozoic to Lower Jurassic. The intensity of brittle deformation is quantified by the H/S dimensionless parameter and its spatial distribution in the study area relates to the local stress produced by the kinematics of RGF and AF. The (multiple) paleostress are computed by an original methodology that includes the inversion of both faults and near orthogonal fracture systems. Results confirm the Meso-Cenozoic strike slip-kinematics of the RGF-AF characterized by a right-lateral event that followed an older left-lateral one.