Brittle deformation relating to the Carboniferous–Cretaceous evolution of the Lambert Graben, East Antarctica: A precursor for Cenozoic relief development in an intraplate and glaciated region

Abstract

Stress inversions of kinematic data measured from brittle deformation structures exposed in the southern Prince Charles Mountains have been carried out to elucidate the drivers of intracontinental deformation responsible for the development of the Lambert Graben, East Antarctica. Four palaeostress fields ( D1– D4) were identified from these data, which when coupled with pre-existing geochronological and sedimentological evidence, provide a clear deformation framework. The architecture of the Lambert Graben is dominantly defined by north–south trending D2 and northeast–southwest trending D3 faults that formed respectively during: (1) Carboniferous–Permian intracontinental extrusion and (2) Cretaceous transtensional tectonics related to the dispersion of East Gondwana. Interestingly, sub-ice topography in the southern Prince Charles Mountains and further south towards the Gamburtsev Mountains is defined by bedrock lineaments that parallel the orientations of the main fault arrays. Previous work shows that the development of relief in the southern Prince Charles Mountains is Tertiary in age and probably not associated with Carboniferous–Permian or Cretaceous tectonic events. Based on a clear spatial link between the orientations of faults and bedrock lineaments, we suggest that inherited fault zones were integral in accommodating uplift driven by plate flexure as a response to crustal unloading during glacial incision.