Fault-controlled Ancient Hydrothermal Systems in North Victoria Land, Antarctica

Northern Victoria Land (NVL) at the Pacific end of the Transantarctic Mountains is a key region for understanding the geodynamics of East Antarctica and provides a window to its crustal architecture. The structural frame of NVL derives from polyphase tectonics and is mainly characterised by NW-SE striking lineaments, which transect the NVL crust and the Cenozoic rift basins of the Ross Sea and which are responsible for the reactivation of inherited Paleozoic - Mesozoic discontinuities. We present preliminary data on regional scale metasomatic and hydrothermal alterations linked to different exhumed fault systems in NVL. Main hydrothermal alterations are: (i) Mg-Ca- carbonation and silicification of mafic and ultramafic rocks along faults and brittle-ductile shear zones at the boundary between the Wilson and Bowers terranes; (ii) Mg-Ca-Fe carbonation of metavolcanic rocks accompanied by syntectonic carbonate coatings on fault planes, hydraulic brecciation, and quartz-carbonate veining in the Bowers Terrane and at the Bowers-Robertson Bay terranes boundary; (iii) epidote and chlorite indurated gouge and cataclasite in fault cores in granitoid rocks and epidotization of metabasalt in the Lanterman Range and in the Bowers Terrane and in Ferrar Dolerite. We discuss the fluid-rock interaction during faulting and the relevance of these hydrothermal systems in reconstructing the tectonic history of this sector of the Transantartic Mountains