Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9522295 | Earth and Planetary Science Letters | 2005 | 12 Pages |
Abstract
We present a new glacial chronology for the last glacial interglacial transition, c. 20 to 10 ka, from the Cobb Valley, NW Nelson, New Zealand, based on a suite of 10Be and 26Al cosmogenic exposure ages. This chronology describes one of the most comprehensive deglaciation sequences from a late Quaternary valley system in the Southern Hemisphere. We chronicle the decay from the last (local) glacial maximum as follows: onset of the last deglaciation that commenced no earlier than 18-19 ka, followed by numerous short-term still-stands and/or minor re-advances over the ensuing 3-4 kyr, and complete evacuation of ice by 14 ka. We find no evidence to indicate a late glacial re-advance commensurate with the Northern Hemisphere Younger Dryas chronozone. The absence of a major glacial re-advance in this valley during the latter stages of the last glacial interglacial transition (LGIT) precludes a thermal decline in excess of about 3 °C and suggests no decline. The absence of late LGIT re-advances in the mountains of North-West Nelson, while deglacial readvances occurred in the main ranges of the Southern Alps can be best explained if westerly wind forcing rather than large-scale thermal decline is the primary control on glacier fluctuations, at least during the deglaciation. These findings challenge models of global climate change predicated on synchrony of millennial-scale glacial transitions due to thermal changes between Northern and Southern Hemispheres.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Earth and Planetary Sciences (General)
Authors
James Shulmeister, David Fink, Paul C. Augustinus,