DOI: 10.1016/j.quascirev.2012.10.034
Scopus记录号: 2-s2.0-84983584981
论文题名: The Last Glacial Maximum at 44°S documented by a 10Be moraine chronology at Lake Ohau, Southern Alps of New Zealand
作者: Putnam A.E. ; Schaefer J.M. ; Denton G.H. ; Barrell D.J.A. ; Birkel S.D. ; Andersen B.G. ; Kaplan M.R. ; Finkel R.C. ; Schwartz R. ; Doughty A.M.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2013
卷: 62 起始页码: 114
结束页码: 141
语种: 英语
英文关键词: 10Be
; Antarctica
; Cosmogenic nuclide
; Geomorphology
; Glacier
; Glaciology
; Last Glacial Maximum
; Last Glacial termination
; New Zealand
; Paleoclimatology
; Patagonia
; Snowline
; Southern Alps
; Southern Ocean
; Surface-exposure dating
Scopus关键词: Atmospheric temperature
; Catchments
; Climatology
; Geomorphology
; Glacial geology
; Glaciers
; Lakes
; Landforms
; Sea ice
; 10Be
; Antarctica
; Cosmogenic nuclides
; Glaciology
; Last Glacial Maximum
; Last glacial terminations
; New zealand
; Paleoclimatology
; Patagonia
; Snowline
; Southern Alps
; Southern ocean
; Surface-exposure dating
; Oceanography
; air temperature
; bedrock
; beryllium isotope
; chronology
; cosmogenic radionuclide
; experimental study
; geomorphological mapping
; glacier advance
; glacier retreat
; glaciology
; Last Glacial Maximum
; moraine
; paleoclimate
; reconstruction
; sea surface temperature
; snowline
; stratification
; Antarctica
; Lake Ohau
; New Zealand
; Patagonia
; South Island
; Southern Alps
; Southern Ocean
英文摘要: Determining whether glaciers registered the classic Last Glacial Maximum (LGM; ∼26,500-∼19,000 yrs ago) coevally between the hemispheres can help to discriminate among hypothesized drivers of ice-age climate. Here, we present a record of glacier behavior from the Southern Alps of New Zealand during the 'local LGM' (LLGM). We used10Be surface-exposure dating methods and detailed glacial geomorphologic mapping to produce a robust chronology of well-preserved terminal moraines deposited during the LLGM near Lake Ohau on central South Island. We then used a glaciological model to estimate a LLGM glacier snowline and atmospheric temperature from the Ohau glacier record. Seventy-three10Be surface-exposure ages place culminations of terminal moraine construction, and hence completions of glacier advances to positions outboard of present-day Lake Ohau, at 138,600 ± 10,600 yrs, 32,520 ± 970 yrs ago, 27,400 ± 1300 yrs ago, 22,510 ± 660 yrs ago, and 18,220 ± 500 yrs ago. Recessional moraines document glacier recession into the Lake Ohau trough by 17,690 ± 350 yrs ago. Exposure of an ice-molded bedrock bench located inboard of the innermost LLGM moraines by 17,380 ± 510 yrs ago indicates that the ice tongue had receded about 40% of its overall length by that time. Comparing our chronology with distances of retreat suggests that the Ohau glacier terminus receded at a mean net rate of about 77 m yr-1and its surface lowered by 200 m between 17,690 and 17,380 yrs ago. A long-term continuation of ice retreat in the Ohau glacier catchment is implied by moraine records at the head of Irishman Stream valley, a tributary of the Ohau glacier valley. The Irishman Stream cirque glacier advanced to produce a set of Lateglacial moraines at 13,000 ± 500 yrs ago, implying that the cirque glacier was less extensive prior to that advance. We employed a glaciological model, fit to these mapped and dated LLGM moraines, to derive snowline elevations and temperature parameters from the Ohau glacier record. The modeling experiments indicate that a snowline lowering of 920 ± 50 m and temperature depression of 6.25 ± 0.5 °C below modern values allows for the Ohau glacier to grow to an equilibrium position within the LGM moraine belt. Taken together with a glaciological simulation reported from the Irishman Stream valley, snowlines and temperatures increased by at least ∼520 m and ∼3.6 °C, respectively, between ∼18,000 and ∼13,000 yrs ago. Climate parameters derived from the Ohau glacier reconstruction are similar to those derived from glacier records from Patagonia, to air temperature indicators from Antarctica, as well as to sea-surface temperature and stratification signatures of the Southern Ocean. We think that the best explanation for the observed southern LLGM is that southern winter duration modulated Southern Ocean sea ice, which in turn influenced Southern Ocean stratification and made the surface ocean cooler. Orbitally induced cooling of the Southern Ocean provides an explanation for the LLGM in the Southern Alps having been coincident with the northern LGM. We argue further that the global effect of North Atlantic stadials led to disturbance of Southern Ocean stratification, southward shifts of the subtropical front, and retreat of Southern Alps glaciers. Collapse of Southern Ocean stratification during Heinrich Stadial-1, along with attendant sea-surface warming, triggered the onset of the Last Glacial termination in the Southern Alps of New Zealand. © 2012 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/60720
Appears in Collections: 过去全球变化的重建
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作者单位: Lamont-Doherty Earth Observatory, 61 Rt. 9W, Palisades, NY 10944, United States; Department of Earth Sciences, Climate Change Institute, University of Maine, Orono, ME 04469, United States; Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, United States; GNS Science, Private Bag 1930, Dunedin 9054, New Zealand; Department of Geosciences, University of Oslo, 0316 Oslo, Norway; Department of Earth and Planetary Sciences, University of California, Berkeley, CA 95064, United States; Antarctic Research Centre, School of Earth Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
Recommended Citation:
Putnam A.E.,Schaefer J.M.,Denton G.H.,et al. The Last Glacial Maximum at 44°S documented by a 10Be moraine chronology at Lake Ohau, Southern Alps of New Zealand[J]. Quaternary Science Reviews,2013-01-01,62