Early glacial maximum and deglaciation at sub-Antarctic Marion Island from cosmogenic 36Cl exposure dating

QUATERNARY SCIENCE REVIEWS

卷:231

Article

Rudolph, Elizabeth M.¹  Hedding, David W.²  Fabel, Derek³  Hodgson, Dominic A.⁴  Gheorghiu, Delia M.³  Shanks, Richard³  Nel, Werner¹ 

[1] Univ Ft Hare, Dept Geog & Environm Sci, 1 King Williamstown Rd, ZA-5700 Alice, South Africa

[2] Univ South Africa, Dept Geog, Unisa, POB 392, ZA-0003 Florida, South Africa

[3] Scottish Univ Environm Res Ctr, Rankine Ave, E Kilbride G75 0QF, Lanark, Scotland

[4] British Antarctic Survey, Madingley Rd, Cambridge CB3 0ET, England

关键词: Marion island;    Sub-Antarctic;    Cosmogenic isotopes;    Chlorine-36;    Last glacial maximum;    MIS 3;    Pleistocene;    Geomorphology;    Glacial;    Glaciation;    Southern ocean;   

DOI  :  10.1016/j.quascirev.2020.106208

来源: Elsevier

【 摘 要 】

Southern Hemisphere glacial chronologies can provide valuable insights into interactions between glaciation and past climate changes, but are not well constrained on most sub-Antarctic islands. We present the first cosmogenic Cl-36 exposure ages of deglaciated bedrock surfaces and moraine deposits from sub-Antarctic Marion Island in the southern Indian Ocean. Results show that the ice reached a local Last Glacial Maximum before 34 ka and retreated, with no re-advances, but possibly minor stand stills, until similar to 17 ka. This early deglaciation left island surfaces below 850 m a.s.l. ice-free after similar to 19 ka, and any subsequent advances during the Antarctic Cold Reversal or Holocene cooling periods would have been restricted to the interior. This glacial chronology is similar to that of some other sub-Antarctic Islands (e.g. the Kerguelen archipelago, Auckland and Campbell islands, and possibly South Georgia) and a number of other Southern Hemisphere glaciers (e.g. in Patagonia and New Zealand) and adds to evidence that suggest the Southern Hemisphere was in a glacial maxima earlier than the global LGM. We suggest a combination of declining temperatures, a northward migration of oceanic fronts and the Southern Hemisphere westerly winds (causing precipitation changes), as well as the physiography of Marion Island, created optimal conditions for glacier growth during Marine Isotope Stage (MIS) 3 instead of MIS 2. Our findings redefine the glacial history of Marion Island, and have implications for future investigations on post-glacial landscape development and ecological succession. (C) 2020 Elsevier Ltd. All rights reserved.

【 授权许可】

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