Rapid ice-sheet growth and initiation of the last glaciation |
| |
Authors: | R.G. Johnson J.T. Andrews |
| |
Affiliation: | 1. Corporate Technology Center, Honcywell, Inc., 10701 Lyndale Avenue South, Bloomington, Minnesota 55420 USA;2. University of Colorado, Institute of Arctic and Alpine Research, Boulder, Colorado 80302 USA;3. University of Colorado, Department of the Geological Sciences, Boulder, Colorado 80302 USA |
| |
Abstract: | Calculations based on temperature-corrected oxygen-isotope ratios from deep-sea cores yield a glacioeustatic sea-level fall in excess of 50 m during the first 10,000 yr of the last glaciation, and generally support the local regression of about 70 m inferred from tectonically rising New Guinea beaches. We propose that this rapid glacial buildup depended on high-latitude cooling, and large increases of high-latitude regional winter precipitation in the Laurentide and the Fennoscandian-Barents Sea areas, and that these factors were caused by a critical alteration of North Atlantic Drift currents and their associated subpolar atmospheric circulation. In support of this, faunal data from northeast North Atlantic deep-sea cores show that the glacial buildup was accompanied by a sudden loss of most of the North Atlantic Drift from the Greenland-Norwegian Sea, a factor favoring reduced heat input into the higher latitudes. Subpolar mollusk and foraminifera fauna from elevated marine deposits on the Baffin Island coast, and northwest North Atlantic core data suggest a continuation or an associated restoration of subpolar water west of Greenland as far north as Baffin Bay, a factor favoring precipitation in the northeast Canadian region. Heat transport and atmospheric circulation considerations suggest that the loss of the northeast North Atlantic Drift was itself a major instrument of high-latitude climate change, and probably marked the initiation of major new ice-sheet growth. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|