Morphotectonic architecture of the Transantarctic Mountains rift flank between the Royal Society Range and the Churchill Mountains based on geomorphic analysis

Abstract

Extensional forces within the Antarctic Plate have produced the Transantarctic Mountains rift-flank uplift along the West Antarctic rift margin. Large-scale linear morphologic features within the mountains are controlled by bedrock structure and can be recognized and mapped from satellite imagery and digital elevation models (DEMs). This study employed the Antarctic Digital Database DEM to obtain slope steepness and aspect maps of the Transantarctic Mountains (TAM) between the Royal Society Range and the Churchill Mountains, allowing definition of the position and orientation of the morphological axis of the rift-flank. The TAM axis, interpreted as a fault-controlled escarpment formed by coast-parallel retreat, provides a marker for the orientation of the faulted boundary between the TAM and the rift system. Changes in position and orientation of the TAM axis suggests the rift flank is segmented into tectonic blocks bounded by relay ramps and transverse accommodation zones. The transverse boundaries coincide with major outlet glaciers, supporting interpretation of rift structures between them. The pronounced morphological change across Byrd Glacier points to control by structures inherited from the Ross orogen.

Glimpses of East Antarctica: Aeromagnetic and satellite magnetic view from the central Transantarctic Mountains of East Antarctica

“…The 200-300 km westward shift of the rift boundary north of CTAM also corresponds to NE trending lineaments in the bed elevation data at Byrd Glacier in the south and Mulock Glacier in the north. The MulockByrd area was previously considered a Mesozoic to Cenozoic rift accommodation zone [Demyanick and Wilson, 2007;Fitzgerald, 2002;Wilson, 1999], but the integrated magnetic data indicate that initial offset in the cratonic rifted margin probably dates to Neoproterozoic separation of East Antarctica and its conjugate Rodinia neighbor. This is supported near Byrd Glacier by deflections in Ross Orogen structures within Lower Cambrian strata [Rowell et al, 1986], changes in isotopic composition of Ross age granites [Borg et al, 1990;Borg and DePaolo, 1994], and contrast in rock types across Byrd Glacier [Stump, 1995], all of which indicate control by preexisting basement structures on Ross age features.…”