TY - JOUR

T1 - Eleven phases of Greenland Ice Sheet shelf-edge advance over the past 2.7 million years

AU - Knutz, Paul C.

AU - Newton, Andrew M.W.

AU - Hopper, John R.

AU - Huuse, Mads

AU - Gregersen, Ulrik

AU - Sheldon, Emma

AU - Dybkjær, Karen

N1 - Funding Information: TGS Geophysical Company is acknowledged for use of seismic data. A.M.W.N. was supported by the Natural Environmental Research Council (NERC grant reference number NE/K500859/1) and Cairn Energy for PhD funding. Publisher Copyright: © 2019, The Author(s), under exclusive licence to Springer Nature Limited.

PY - 2019

Y1 - 2019

N2 - The reconstruction of former ice sheets is important for testing Earth system models that can assess interactions between polar ice sheets and global climate, but information retrieved from contemporary glaciated margins is sparse. In particular, we need to know when ice sheets began to form marine outlets and the mechanisms by which they advance and retreat over timescales from decades to millions of years. Here, we use a dense grid of high-quality two-dimensional seismic reflection data to examine the stratigraphy and evolution of glacial outlets, or palaeo-ice streams, that drained the northwest Greenland Ice Sheet into Baffin Bay. Seismic horizons are partly age constrained by correlation with cores from drill sites. Progradational units separated by onlap surfaces record 11 major phases of shelf-edge ice advance and subsequent transgression since the first ice-sheet expansion 3.3–2.6 million years ago. The glacial outlet system appears to have developed in four stages, each potentially caused by tectonic and climatic changes. We infer that an abrupt change in ice-flow conditions occurred during the mid-Pleistocene transition, about 1 million years ago, when ice movement across the shelf margin changed from widespread to a more focused flow (ice streams), forming the present-day glacial troughs.

AB - The reconstruction of former ice sheets is important for testing Earth system models that can assess interactions between polar ice sheets and global climate, but information retrieved from contemporary glaciated margins is sparse. In particular, we need to know when ice sheets began to form marine outlets and the mechanisms by which they advance and retreat over timescales from decades to millions of years. Here, we use a dense grid of high-quality two-dimensional seismic reflection data to examine the stratigraphy and evolution of glacial outlets, or palaeo-ice streams, that drained the northwest Greenland Ice Sheet into Baffin Bay. Seismic horizons are partly age constrained by correlation with cores from drill sites. Progradational units separated by onlap surfaces record 11 major phases of shelf-edge ice advance and subsequent transgression since the first ice-sheet expansion 3.3–2.6 million years ago. The glacial outlet system appears to have developed in four stages, each potentially caused by tectonic and climatic changes. We infer that an abrupt change in ice-flow conditions occurred during the mid-Pleistocene transition, about 1 million years ago, when ice movement across the shelf margin changed from widespread to a more focused flow (ice streams), forming the present-day glacial troughs.

U2 - 10.1038/s41561-019-0340-8

DO - 10.1038/s41561-019-0340-8

M3 - Journal article

AN - SCOPUS:85064571782

VL - 12

SP - 361

EP - 368

JO - Nature Geoscience

JF - Nature Geoscience

SN - 1752-0894

IS - 5

ER -