2002-2003 Science Planning Summary

Geology & Geophysics

Dr. Scott Borg
Program Manager

GO-080-L

NSF/OPP 01-26472
Station: Not based at a station
RPSC POC: John Evans
Research Site(s): South Shetland Islands, Antarctic Peninsula, Spring Point, O'Higgins Base (Chile), Pratt Base-Greenwich Is, Juan Carlos Is, Livingston Is., Low Is., King George Is., Elephant Is.

The Scotia Arc GPS Project: Focus on the Antarctic Peninsula and South Shetland Islands
Dr. Frederick W. Taylor
University of Texas
Institute for Geophysics
fred@utig.ig.utexas.edu

Deploying Team Members: Clifford A Frohlich . Krishnavikas Gudipati . Frederick W Taylor
Research Objectives: The principal aim of the original Scotia Arc GPS (global positioning system) Project (SCARP) was to determine motions of the Scotia Plate relative to adjacent plates and to measure crustal deformation along its margins with special attention to the South Sandwich microplate and Bransfield Strait extension. Current research is confined to the part of the SCARP project that includes researcher’s GPS sites at Elephant Island, the South Shetland Islands, and the Antarctic Peninsula. The British Antarctic Survey provides data from two sites on the Scotia Arc for this project.

Researchers plan to complete the measurements required to quantify crustal deformation related to the opening of the Bransfield Strait and the South Shetland microplate, and to identify any other independent tectonic blocks that the GPS data may reveal. These measurements will be done using ship support during the 2002–2003 season. Five years have passed since researchers did their first measurements, so it should be possible for them to determine quite precise horizontal velocities.

The British Antarctic Survey and the Alfred Wegener Institute have also recognized the importance of the Scotia plate and the Bransfield system. They, too, have used GPS to measure crustal motions in this region and duplicate a number of sites. Researchers on this project expect to publish a joint paper with the British, as well as one with their own interpretations and data.

There are several advantages that justify collecting and analyzing another set of data.

1. Researchers on this project have already established and measured GPS sites on Smith, Low, and Livingston Islands, where other groups have not. These sites significantly extend the dimensions of the South Shetland microplate so that they can determine a more precise pole and recognize any sub-blocks within the South Shetland arc. Smith and Low Islands are near the end of the Bransfield Basin, where relative motion between the South Shetland microplate must somehow terminate, perhaps by faulting along an extension of the Hero fracture zone.

2. Another advantage is that researchers conducted their measurements using fixed-height masts that eliminate all but a fraction of a millimeter of vertical error. Vertical motion associated with post-glacial rebound should be on the order of several millimeters per year, which will eventually be measurable. The fact that mid-Holocene shorelines emerged to more than 20 meters on some South Shetland arc islands suggests that vertical motion is significant. (NSF Award # 01–26472)


Field Season Overview:
GPS fixed survey points for this project were established in the Bransfield Strait/Elephant Island area during the 1997-1998 field season. Each researchers re-measure their positions. Zodiac inflatable boats will transport researchers and equipment between ship and shore. Two 24-hour data collection periods are planned for each site to ensure the minimum 0000 to 2400 GMT day that is necessary to obtain the precision required. The field team may set up a temporary tent camp. They will have sufficient GPS equipment to allow for simultaneous data collection at up to three locations.