Transform-normal extension in the Victoria land Basin (Antarctica)

Abstract

The Victoria Land Basin is the westernmost branch of the Ross Sea rift system. It runs parallel to the Transantarctic Mountains which experienced 5 km of uplift during the Cenozoic. Several subbasins, with more than 6 km of Cenozoic sedimentary fill, were formed along the Victoria Land Basin during the same period. The analysis of multichannel seismic profiles suggests that a large transcurrent system runs along the Lee Arch, at the center of the Victoria Land Basin, which separates the Discovery Graben from the eastern basins. As a result, large asymmetric basins have developed here. They are bounded on one side by the transcurrent fault system and on the other side by normal faults. This structural situation is similar to other large sedimentary basins along continental transforms where transform-normal extension takes place. Previous studies pointed out the strike-slip nature of the Victoria Land Basin. In the present study we propose the Transform-Normal Extension model as the best mechanism to explain the observed structural features and the reconstructed evolution.