Structural and thermochronological constraints to the evolution of the West Antarctic Rift System in central Victoria Land

Abstract

Uncertainty still persists on the structure and evolution of the West Antarctic Rift System, which is one of the largest extensional provinces on Earth. In this paper, we present results of a combined structural and apatite fission track study of the western shoulder of the rift system, in the western coastal area of the Ross Sea between the Reeves and the Mawson glaciers. Structural data indicate that the onshore fault pattern is dominated by N–S striking right‐lateral strike‐slip to transtensional fault systems and their related subsidiary fault populations in the damage zones. Thermochronological data support a Cenozoic age for these faults and, in particular, the onset of the oblique rifting event at about 50 Ma, in Eocene times. Apatite fission track analyses also suggest the possible occurrence of an older cooling/exhumation event in Cretaceous times. When integrated with the geological and geophysical data sets available in the literature, our structural and thermochronological data provide further support to the interpretation of Cenozoic oblique rifting in the West Antarctic Rift System as induced by the transfer of dextral shear from the mid oceanic ridge in the Southern Ocean, into the Antarctic Plate interior.