A Glacial Chronology of the Strait of Magellan
Abstract
In order to address the fundamental question of when and why Ice Age climates begin and end in South America and the Southern Hemisphere, robust glacial chronologies are needed. As previous studies have demonstrated, well-preserved glacial deposits left by large ice sheet lobes adjacent to the Strait of Magellan (52°S; Chile) in southernmost South America provide a unique opportunity to reconstruct the timing and structure of at least the last two glaciations and terminations. We apply precise 10Be surface exposure dating of glacially deposited moraine boulders, along with detailed geomorphic mapping of the area. Here we present new results for a sequence of six moraine sets at the Strait of Magellan that span 18-28 ka and 60-70 ka showing that boulders from the outermost moraine ridge dated thus far are marine isotope stage (MIS) 4 in age. This coincides with a glacial maximum in New Zealand's Southern Alps (44°S), providing evidence for a hemispheric-scale full glacial maximum during MIS-4, similar in size to MIS-2. Inboard the MIS-4 moraine, mapping and dating of several moraines fringing the Strait of Magellan area will afford us insight into the fine structure of the local Last Glacial Maximum and its regional, hemispheric and inter-hemispheric significance. Establishment of such detailed glacier records in southernmost South America and throughout the Southern Hemisphere will help to test proposed mechanisms for the last two glacial maxima and their terminations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP21A2257P
- Keywords:
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- 1605 Abrupt/rapid climate change;
- GLOBAL CHANGEDE: 1616 Climate variability;
- GLOBAL CHANGEDE: 1620 Climate dynamics;
- GLOBAL CHANGEDE: 4901 Abrupt/rapid climate change;
- PALEOCEANOGRAPHY