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Progressive unpinning of Thwaites Glacier from newly identified offshore ridge: Constraints from aerogravity
Author(s) -
Tinto K. J.,
Bell R. E.
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl049026
Subject(s) - geology , glacier , trough (economics) , ridge , ice stream , bathymetry , glacier morphology , tidewater glacier cycle , ice shelf , geomorphology , glacier ice accumulation , iceberg , ice tongue , submarine pipeline , oceanography , front (military) , ice sheet , sea ice , paleontology , cryosphere , pregnancy , genetics , lactation , ice calving , biology , economics , macroeconomics
A new bathymetric model from the Thwaites Glacier region based on IceBridge airborne gravity data defines morphologic features that exert key controls on the evolution of the ice flow. A prominent ridge with two distinct peaks has been identified 40 km in front of the present‐day grounding line, undulating between 300–700 m below sea level with an average relief of 700 m. Presently, the Thwaites ice shelf is pinned on the eastern peak. More extensive pinning in the past would have restricted flow of floating ice across the full width of the Thwaites Glacier system. At present thinning rates, ice would have lost contact with the western part of the ridge between 55–150 years ago, allowing unconfined flow of floating ice and contributing to the present‐day mass imbalance of Thwaites Glacier. The bathymetric model also reveals a 1200 m deep trough beneath a bight in the grounding line where the glacier is moving the fastest. This newly defined trough marks the lowest topographic pathway to the Byrd Subglacial Basin, and the most likely path for future grounding line retreat.