Where tectonics meets ice‑sheet dynamics: roots of West Antarctica’s next ice‑sheet collapse

• Main Author: Gohl, Karsten
• Format: Conference Object
• Language: unknown
• Published: 2019
• Subjects: Amundsen Sea; Antarc*; Antarctic; Antarctica; Bellingshausen Sea; Ice Sheet; Marie Byrd Land; Ross Sea; West Antarctica
• Online Access: https://epic.awi.de/id/eprint/49842/; https://hdl.handle.net/10013/epic.5f07de69-da70-4b08-96ea-4148d43b30a8

West Antarctica is one of the most fascinating and challenging regions for studying the relationship and interplay of geodynamic, tectonic, and sedimentation processes as well as past and present ice-sheet dynamics. Its mostly rift-related tectonic evolution, driven by yet largely enigmatic mantle-dynamic processes, led to a topographic and morphological setting for a dominantly submarine-based ice sheet that is highly sensitive to climate change and ocean warming. Originally an assemblage of various Palaeozoic and Mesozoic crustal blocks and mobile belts, West Antarctica’s transformation into the worldwide second largest continental rift system began when subduction at the East Gondwana margin partially stalled and the New Zealand micro-continent separated from Antarctica in the mid-Cretaceous. Crustal extension continued in West Antarctica in various phases creating major rift basins of thin crust, but partial uplift also occurred with the Marie Byrd Land dome event by an intercepting mantle plume. Cretaceous rifting and continental breakup as well as later stages of West Antarctic Rift System activities formed the basement architecture of the major embayments of the Ross Sea, Amundsen Sea and Bellingshausen Sea, which have acted as prominent outlet regions for the West Antarctic Ice Sheet. The onset of early ice caps and glaciers likely occurred in highly elevated ranges already in the early Cenozoic, but seismic and sediment core records indicate that first glaciers and ice-streams reached the costs and inner shelves not before the Oligocene. A palaeotopographic model of Antarctica, derived from a study on offshore/onshore sedimentary erosion-transport-deposition mass balance, indicates that an early continuous West Antarctic Ice Sheet may have formed on a land-surface higher than today and above sea level in the early Oligocene. Seismic and sediment records from the continental shelves and rises of the West Antarctic margin demonstrate that most of the terrigenous sedimentary volume deposited has been ...