A cosmogenic nuclide chronology of the last glacial transition in North-West Nelson, New Zealand—new insights in Southern Hemisphere climate forcing during the last deglaciation
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Date
2005-05-15
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Elsevier
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. © 2005 Elsevier B.V.
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Keywords
New Zealand, Age estimation, Paleoclimatology, Southern Hemisphere, Glaciers, Climatic change
Citation
Shulmeister, J., Fink, D., & Augustinus, P. C. (2005). A cosmogenic nuclide chronology of the last glacial transition in North-West Nelson, New Zealand—new insights in Southern Hemisphere climate forcing during the last deglaciation. Earth and Planetary Science Letters, 233(3–4), 455-466. doi:10.1016/j.epsl.2005.02.028