Paleocean Circulation

The ocean circulation is very sensitive to the ocean bottom (bathymetry) and to the placement of the continental margins. Currents like the Gulf Stream and the Kuroshio lie along the western continental margins, while the Agulhas is locked to the eastern side of South Africa.

The Antarctic Circumpolar Current (ACC), the largest in the world, makes a circuitous route around the Antarctic continent, snaking through Drake Passage, along the South American continental margin and past the Kerguelen plateau. Most oceanographers consider the bathymetry and continental boundaries as fixed. But marine geologists know that both change substantially over longer time scales, as the tectonic plates shift. This has enormous implications for the ocean.

The ACC, for example, didn’t exist 30 million years ago when the Drake Passage and Tasman gateway were both closed. There was no ice on Antarctica then, and this is probably not a coincidence.

In this project, we will examine how specific ocean currents change in response to tectonic motion. There are numerous possibilities, including the global overturning circulation (which wasn’t always intensified in the Atlantic) and the ACC.

The exact topic will be decided together with the student, depending on interests. The work will be jointly supervised by Gaina, who is involved with reconstructions of ocean bathymetry, and LaCasce, who studies ocean circulation. Thus the student will gain experience both in marine geology and ocean modeling, a unique combination of skills. 

Continental configurations at present, 55, 132 and 250 million years ago. In the last case, the continents were clumped together in a single super-continent, called Pangea. The ocean circulation was much different then than today.

 

Published Sep. 7, 2018 9:46 AM - Last modified Sep. 7, 2018 9:46 AM

Scope (credits)

60