APATITE TRIPLE DATING IN ANTARCTICA

[1] Apatite triple dating (fission track, U-Pb and U-Th/He techniques) has been applied to detrital grains from the sedimentary core drilled during the ANDRILL 2A project, which documents the Miocene history of the Victoria Land Basin (western Ross Sea). High-temperature cooling ages show two main clusters (about 30 and 500 Ma) whereas most of low-temperature data are late Oligocene-Early Miocene in age. These latter data are related to the exhumation of the Transantarctic Mountains south of the Discovery Accommodation Zone. Comparison between low-temperature ages suggests that the Transantarctic Mountains have been in a phase of post-orogenic decay since at least 30 Ma. The Oligocene U-Pb data demonstrate the presence of a volcanic event well before the McMurdo volcanic group, whose onset is commonly places at 19 Ma. The location of the volcanic centers is unknown, but they could be below the Ross Ice Shelf south of drilling site. As a whole, these data indicate a major flow of sediments from south to north with only minor contributions from nearby outlet glaciers of the East Antarctic Ice Sheet