Fire and Ice - Tectonic and glacial history of the Amundsen Sector, West Antarctica

• Main Author: Lindow, Julia
• Other Authors: Spiegel, Cornelia, Bach, Wolfgang
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2014
• Subjects: West Antarctica; Thermochronology; Fission Track Dating; Apatite Helium Dating; Cosmogenic Nuclides; Geodynamics; Tectonics; Glacial Retreat; Holocene; Cretaceous; Cenozoic; Exhumation; Erosion; Surface Exposure Dating; Amundsen Sea Embayment; Pine Island Bay; 550; 550 Earth sciences and geology; ddc:550; Antarctic; Amundsen Sea; West Antarctic Ice Sheet; Island Bay; Kohler Range; Antarc*; Antarctica; Ice Sheet; Pine Island
• Online Access: https://media.suub.uni-bremen.de/handle/elib/794; https://nbn-resolving.org/urn:nbn:de:gbv:46-00104195-15

West Antarctica has gone through major tectonic changes beginning in the Cretaceous (145 - 66 Ma). With the West Antarctic Rift System, the area also holds one of the largest continental rifts known on Earth. However, the West Antarctic Rift System is almost completely buried beneath West Antarctic Ice Sheet, as a result details of its geodynamic history are sparse and its tectonic evolution is still poorly understood. Furthermore, with the 'Amundsen Sector', West Antarctica hosts one of the most rapidly changing parts of the West Antarctic Ice Sheet. With the fastest flowing ice streams in Antarctica, especially the eastern areas are characterized by rapid ice sheet thinning and grounding-line retreat. Like data on West Antarctica's geodynamics, constraints on the deglacial history are limited to either marine sedimentary data or a few isolated nunataks. Thus it is difficult to assess the long-term deglacial history of the area, too. In this study we reconstructed the shallow crustal (~15 - 1 km) evolution of the ~1000 km long Amundsen Sector of West Antarctica and alongside the rift system. Thereby we applied three lowtemperature thermochronology analysis: apatite (U-Th-Sm)/He, apatite fission track and zircon fission track, and combined their results in inverse thermal history models. We further utilized detrital information on the dominantly ice-covered hinterland through the analysis of ice rafted debris extracted from marine sediments. Finally, to address the glacial retreat after the Last Glacial Maximum (ca. 23 - 19 ka) we applied 10Be-surface exposure dating in two key areas onshore of the eastern and mid Amundsen Sector, namely Pine Island Bay and the Kohler Range. Together, all three thermochronology systems yield early Cretaceous to early Miocene ages (121 - 18 Ma), with a dominant cluster in the mid- to late Cretaceous. Zircon fission track data ranges between 108 - 80 Ma, apatite fission track between 121 - 28 Ma, with narrow track lengths distributions and mean track lengths of 14.9 - 13.1 um, ...