Terrestrial and Marine Evidence for a Middle Miocene Onset of Polar Conditions in the Ross Sea Region, Antarctica
The climate transition from a dominantly wet-based temperate to a dominantly dry-based polar ice sheet represents a major step in the evolution of the Antarctic cryosphere. Terrestrial glacial deposits from the Olympus Range in the Dry Valleys sector of the Transantarctic Mountains register an abrupt shift in glacier thermal regimes, from wet to cold based, between 14.1 and 13.9 Ma. On the Ross Sea outer continental shelf, seismic stratigraphic results suggest that mega scale prograding wedges with sub-aqueous out wash channels existed during the early and middle Miocene, at least from ~18-14Ma. Similar morphological features are notably absent within younger middle Miocene strata on the outer continental shelf. The absence of prograding wedge strata and channels suggests that the marine terminous of the ice sheet experienced a shift from dominantly wet to dry basal conditions at ~14Ma, similar to that registered in the Olympus Range at about the same time. Despite the inability to make physical correlation from the Tranantarctic Mountains to the outer continental shelf at the scale of individual events, the available chrono-stratigraphic control indicates there was a regional transition in the Antarctic Cryosphere from a wet to a dry base affecting proximal terrestrial and distal marine settings during the middle Miocene.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 0768 Thermal regime