USAP-DC

Intellectual Merit:
Opening of Drake Passage and the West Scotia Sea south of Tierra del Fuego broke the final continental barrier to onset of a complete Antarctic Circumpolar Current (ACC). Initiation of the ACC has been associated in time with a major, abrupt, drop in global temperatures and the rapid expansion of the Antarctic ice sheets at 33-34 Ma. Events leading to the formation of the Drake Passage gateway are poorly known. Understanding the tectonic evolution of the floor of the Central Scotia Sea (CSS) and the North Scotia Ridge is a key to this understanding. Previous work has demonstrated that superimposed constructs formed a volcanic arc that likely blocked direct eastward flow from the Pacific to the Atlantic through the opening Drake Passage gateway as the active South Sandwich arc does today. The PIs propose a cruise to test, develop and refine, with further targeted mapping and dredging, their theory of CSS tectonics and the influence it had on the onset and development of the ACC. In addition they propose an installation of GPS receiver to test their paleogeographic reconstructions and determine whether South Georgia is moving as part of the South American plate.

Broader impacts:
A graduate student will be involved in all stages of the research. Undergraduate students will also be involved as watch-standers. A community college teacher will participate in the cruise. The PIs will have a website on which there will be images of the actual ocean floor dredging in operation. The teacher will participate with web and outreach support through PolarTREC. Results of the cruise are of broad interest to paleoceanographers, paleoclimate modelers and paleobiogeographers.A network of four continuous Global Navigational Satellite Systems (GNSS) receivers was installed on the bedrock of South Georgia in the Southern Ocean in 2013 and 2014. An additional receiver on a concrete foundation provides a tie to a tide gauge, part of the United Kingdom South Atlantic Tide Gauge Network. The GNSS receivers have already provided data suggesting that the South Georgia microcontinent (SGM) is moving independent of both the South American plate to the north and the Scotia plate to the south. The data also demonstrate that the SGM is being uplifted.

Person	Role
Dalziel, Ian W.	Investigator and contact
Lawver, Lawrence	Co-Investigator
Krissek, Lawrence	Investigator

Antarctic Earth Sciences	Award # 1246111
Antarctic Glaciology	Award # 1246111

USAP-1246111_1

None in the Database

Repository	Title (link)	Format(s)	Status
UNAVCO GPS/GNSS Data	South Georgia: SOG1, SOG2, SOG3	None	exists
Marine Geoscience Data System	Nathaniel B Palmer NBP 1408	None	exists
British Antarctic Survey	BAS Geological Collection: Central Scotia Sea (full data link not provided)	None	exists

1. Dalziel, I.W.D., Smalley, R., Lawver, L.A., Gomez, D., Teferle, F.N., Hunegnaw, A., Saustrop, S. South Georgia microcontinent: tectonic and paleoenvironmental implications of preliminary GPS data Geological Society of America Annual Meeting, Phoenix, Arizona, September 2019 Lawver, L.A., Dalziel, I.W.D., Davis, M., and Saustrup, S. Changing plate boundaries in and around the South Georgia microcontinent. Geological Society of America, Annual Meeting, Phoenix Arizona, September 2019 Teferle, F.N., Dalziel, I.W.D., Hunegnaw, A, Williams, S.D.P., Woodworth, P.L., Smalley, Lawver, L.A. Present-day land and sea level changes around South Georgia Island: results from precise levelling, GNSS, tide gauge and satellite altimetry measurements. 13th International Symposium on Antarctic Earth Science, Incheon, South Korea, July 2019