Drake Passage and Cenozoic climate: An open and shut case?

Abstract

[1] Drake Passage opening has often been viewed as a single, discrete event, possibly associated with abrupt changes in global circulation and climate at or near the Eocene-Oligocene boundary. A new plate tectonic model, based on recent reinterpretations of the opening history of basins in the Scotia Sea, suggests that an effective ocean gateway may have developed even earlier, during the middle Eocene. This is consistent with a growing body of evidence from sediment core proxy data for Eocene changes in Southern Ocean circulation and biological productivity. The period between earliest opening after 50 Ma and the latest Eocene was characterized by the evolution of various current pathways across the subsiding continental shelves and intervening deep basins. This shallow opening may have caused important changes in Southern Ocean circulation, contributing to Eocene cooling and the growth of Antarctic ice sheets.

Deep-sea pre-glacial to glacial sedimentation in the Weddell Sea and southern Scotia Sea from a cross-basin seismic transect

“…The ACC is not fully developed because South America was still connected to Antarctica with shallow water gateways ( Fig. 12A; Livermore et al, 2007), but Weddell Bottom Water could have formed due to sea ice. Either way, the mound feature is prominent enough that it warrants future investigation.…”

The Kalahari Epeirogeny and climate change: differentiating cause and effect from core to space

“…It remains to be resolved if the carbon budget changes related to the Kalahari epeirogeny balanced or changed the end Cretaceous greenhouse world to such a degree that it became a forcing factor in stimulating the onset of atmospheric CO 2 decline and global cooling at the end of the Cretaceous (e.g. Jenkyns et al, 2004), long before the more dramatic cooling during the subsequent opening of the Drake Passage at ~50 Ma (Scher and Martin, 2006;Livermore et al, 2007).…”

Links between CO<sub>2</sub>, glaciation and water flow: reconciling the Cenozoic history of the Antarctic Circumpolar Current

“…If the opening of the Tasman Passage between Australia and Antarctica is relatively well constrained with progressive deepening between 35 and 30 Ma , there are still numerous uncertainties in the timing of the opening of Drake Passage (Barker and Burrell, 1977;Lawver and Gahagan, 2003;Livermore et al, 2007;Scher and Martin, 2006), with earliest estimates pointing toward the early Eocene (Eagles and Jokat, 2014;Eagles et al, 2006). Consequently, the evolution of the ACC through time between the Eocene and the Miocene remains unclear.…”