Lake core record of Grinnell Glacier dynamics during the latest Pleistocene deglaciation and the Younger Dryas, Glacier National Park, Montana, USA

摘要

Few records in the alpine landscape of western North America document the geomorphic and glaciologic response to climate change during the Pleistocene-Holocene transition. While moraines can provide snapshots of glacier extent, high-resolution records of environmental response to the end of the Last Glacial Maximum, Younger Dryas cooling, and subsequent warming into the stable Holocene are rare. We describe the transition from the late Pleistocene to the Holocene using a similar to 17,000-yr sediment record from Swiftcurrent Lake in eastern Glacier National Park, MT, with a focus on the period from similar to 17 to 11 ka. Total organic and inorganic carbon, grain size, and carbonitrogen data provide evidence for glacial retreat from the late Pleistocene into the Holocene, with the exception of a well-constrained advance during the Younger Dryas from 12.75 to 11.5 ka. Increased detrital carbonate concentration in Swiftcurrent Lake sediment reflects enhanced glacial erosion and sediment transport, likely a result of a more proximal ice terminus position and a reduction in the number of alpine lakes acting as sediment sinks in the valley. (C) 2015 University of Washington. Published by Elsevier Inc. All rights reserved.