MULTI-DIMENSIONAL APPLICATIONS OF cGPS DATA IN THE ANTARCTIC PENINSULA: CONSTRAINTS FOR PAST AND FUTURE MODERATE ICE SHEET COLLAPSE FROM GPS REBOUND, MULTIBEAM BATHYMETRY AND MANTLE VISCOSITIES

This paper presents the framework for a detailed reconstruction of past and future ice sheet conditions in the Northern Antarctic Peninsula. This paper presents empirical evidence of vertical crustal rebound from the Palmer Station cGPS station as a means to better constrain ice thicknesses along a Palmer Station flow path. The Palmer flow path represents a paleo ice stream extending from the accumulation zone in the upper elevations of Anvers Island to the terminus along the continental shelf. The precise location and direction of the flow path was constrained by nearly complete swath map bathymetry available for Western side of the Antarctic Peninsula. In addition to using elevations of bedrock, trim lines and the influence of surrounding topography and glaciers, we utilize a complete vertical crustal rebound curve refined by the cGPS data, previous uplift estimates and reasonable mantle viscosities to reconstruct well constrained ice thicknesses along the Palmer flow path. The vertical rebound curve is fitted to a time scale representative of the deglacial episode since the LGM. Based on the current rate of crustal rebound at Palmer Station we can determine the visco-elastic response of the crust post LGM deglaciation. From this rebound we can calculate total ice thickness. The Palmer Station cGPS vertical rebound data is extended inland towards the Bruce Plateau based on previous estimates of present-day postglacial vertical crustal motion in the region and the chronology of deglaciation along several known paleo ice streams. We are able to construct an isobase map, detailing areas of varying vertical crustal motion and an inferred model for past ice sheet conditions highlighting a large ice dome in the Western Peninsula and along the coast. This study is pertinent to realizing effects of moderate ice sheet disintegration. In conclusion, we evaluate smaller time scale changes in present day mass balance across the Northern Antarctic Peninsula. We categorize this as the elastic rebound component of the cGPS signal at Palmer Station. This evaluation takes into account an increased crustal rebound rate at Palmer Station, from 2.7 mm/yr to 8.5 mm/yr, resulting from post Larsen B breakup glacier surge. We also examine potential corresponding ice mass loss as approximated by bathymetric measurements of glacier trough depths.