Late Ross-orogenic deformation of basement rocks in the northern Deep Freeze Range, Victoria Land, Antarctica: the Lichen Hills Shear Zone

Abstract

Kinematic data from the basement rocks exposed at Lichen Hills in the upper Rennick Glacier, northern Victoria Land, indicate the presence of an intra-Wilson Terrane late Ross-orogenic high-strain reverse shear zone. ENE directed ductile shearing and WSW-directed late-stage brittle reverse faults overprint metasedimentary rocks and thick leucogranites of the Granite Harbour Intrusives. The Ross-orogenic age of the structures is attested by the involvement of leucogranites in ductile shearing and cross-cutting relationships between younger aplitic dykes and brittle deformations. This structural pattern strongly supports a relationship between the Lichen Hills Shear zone and the Wilson Thrust in Oates Land, the eastern branch of a late-Ross bivergent high-strain thrust system. Post-Ross structures are represented by reverse off-sets of the – in this area – Triassic to early Jurassic Beacon strata that are probably related to volcanotectonic events during Ferrar intrusion and the Cenozoic development of NW-SE striking dextral faults and N-S striking large-scale normal faults that parallel the Rennick Glacier