This project studies the relationship between opening of the Drake Passage and formation of the Antarctic ice sheet. Its goal is to answer the question: What drove the transition from a greenhouse to icehouse world thirty-four million years ago? Was it changes in circulation of the Southern Ocean caused by the separation of Antarctica from South America or was it a global effect such as decreasing atmospheric CO2 content? This study constrains the events and timing through fieldwork in South America and Antarctica and new work on marine sediment cores previously collected by the Ocean Drilling Program. It also involves an extensive, multidisciplinary analytical program. Compositional analyses of sediments and their sources will be combined with (U-Th)/He, fission-track, and Ar-Ar thermochronometry to constrain uplift and motion of the continental crust bounding the Drake Passage. Radiogenic isotope studies of fossil fish teeth found in marine sediment cores will be used to trace penetration of Pacific seawater into the Atlantic. Oxygen isotope and trace metal measurements on foraminifera will provide additional information on the timing and magnitude of ice volume changes.
The broader impacts include graduate and undergraduate education; outreach to the general public through museum exhibits and presentations, and international collaboration with scientists from Argentina, Ukraine, UK and Germany.
The project is supported under NSF's International Polar Year (IPY) research emphasis area on "Understanding Environmental Change in Polar Regions". This project is also a key component of the IPY Plates & Gates initiative (IPY Project #77), focused on determining the role of tectonic gateways in instigating polar environmental change.
