Title Reorganization of ice sheet flow patterns in Arctic Canada and the mid- Pleistocene transition
Author Refsnider, K.A.; Miller, G.H.
Author Affil Refsnider, K.A., University of Colorado at Boulder, Institute of Arctic and Alpine Research and Department of Geological Sciences, Boulder, CO
Source Geophysical Research Letters, 37(13), Citation L13502. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276
Publication Date 2010
Notes In English. 26 refs. GeoRef Acc. No: 310659
Index Terms bedrock; chemical composition; glacial deposits; glacial geology; glacier flow; ice sheets; metals; paleoclimatology; Pleistocene; Quaternary deposits; sediments; Arctic region; Canada--Nunavut--Baffin Island; alkali metals; alkaline earth metals; Baffin Island; Ca/Na; calcium; Canada; Cenozoic; chemical ratios; clastic sediments; Eastern Canada; glacial environment; ice movement; interglacial environment; Laurentide ice sheet; middle Pleistocene; Nunavut; Quaternary; sodium; till
Abstract Evidence for the evolution of Laurentide Ice Sheet (LIS) basal thermal regime patterns during successive glaciations is poorly preserved in the geologic record. Here we explore a new approach to constrain the distribution of cold-based ice across central Baffin Island in the eastern Canadian Arctic over many glacial-interglacial cycles by combining till geochemistry and cosmogenic radionuclide (CRN) data. Parts of the landscaped with geomorphic evidence for limited glacial erosion are covered by till characterized by high chemical index of alteration (CIA) values and CRN concentrations requiring complicated burial- exposure histories. Till from regions scoured by glacial erosion have CIA values indistinguishable from local bedrock and CRN concentrations that can be explained by simple exposure following deglaciation. CRN modeling results based on these constraints suggest that the weathered tills were deposited by 1.9 to 1.2 Ma, and by that time the fiorded Baffin Island coastline must have developed close to its modern configuration as piracy of ice flow by the most efficient fiord systems resulted in a major shift in the basal thermal regime across the northeastern LIS. The resultant concentration of ice flow in fewer outlet systems may help explain the cause of the mid-Pleistocene transition from 41- to 100-kyr glacial cycles.
URL http://hdl.handle.net/10.1029/2010GL043478
Publication Type journal article
Record ID 66000016