DOI: 10.1016/j.quascirev.2016.09.019
Scopus记录号: 2-s2.0-84990890116
论文题名: Episodic speleothem deposition tracks the terrestrial impact of millennial-scale last glacial climate variability in SW Ireland
作者: Fankhauser A. ; McDermott F. ; Fleitmann D.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2016
卷: 152 起始页码: 104
结束页码: 117
语种: 英语
英文关键词: Greenland Interstadials
; Last glacial cycle
; NGRIP chronology
; Speleothems
Scopus关键词: Carbon
; Carbon dioxide
; Caves
; Deposition
; Ice
; Isotopes
; Surface waters
; Carbon isotope ratio
; Interstadials
; Isotope fractionation
; Last glacial cycles
; Marine isotope stages
; Mean annual air temperatures
; NGRIP chronology
; Speleothems
; Glacial geology
英文摘要: Eighty four new U-Th ages are presented for twenty randomly selected broken, displaced and reworked calcite speleothems retrieved from clastic sedimentary fill and from isolated bedding-plane shelves in Crag cave (SW Ireland). The dated pre-Holocene samples span much of the last glacial, ranging in age from 85.15 ± 0.60 to 23.45 ± 0.17 ka. Speleothem deposition requires the presence of liquid water, and because Crag cave is a shallow system, deposition is considered likely only when mean annual air temperatures (MAAT) exceed the freezing point of water. Deposition at this mid-latitude ocean-marginal site occurred episodically during MIS5a through to MIS2, synchronously within dating uncertainties, with the timing of Greenland Interstadials (GI). In the latter part of Marine Isotope Stage 3 (MIS3), deposition was particularly intense, consistent with regional scale climate amelioration inferred previously from radiocarbon ages for sparse MIS3 organic and freshwater surficial deposits in N. Ireland. A brief episode of speleothem deposition at c.23.40 ± 0.22 ka coincides with GI-2, demonstrating the sensitivity of the site to brief climate amelioration episodes in Greenland during MIS2. Conditions favourable for speleothem deposition occurred periodically during the last glacial, indicating temperature changes of at least 10 °C between stadials and interstadials at this mid-latitude site. Deposition ceased during Greenland Stadials (GS), including during periods of ice-rafting in the adjacent N. Atlantic Ocean (Heinrich events). Oxygen and carbon isotope ratios of the last glacial speleothems are generally elevated, reflecting non-equilibrium isotope fractionation effects. However, establishment of low δ13C values often occurred within a few decades of climate amelioration, indicating that biogenic CO2 production resumed rapidly at this site, particularly during MIS3. Speleothem δ18O variability was driven largely by long-term changes in the δ18O value of the adjacent North Atlantic surface water, in turn largely reflecting changes in global ice volume. In common with published speleothem datasets, warming episodes in Ireland associated with GI events typically pre-date their timing in the GICC05 and GICC05modelext time scales, but lie comfortably within the maximum counting uncertainties of these ice core age models. © 2016 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59401
Appears in Collections: 过去全球变化的重建
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作者单位: UCD School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland; European Commission-Joint Research Centre (EC-JRC), Retieseweg 111, Geel, Belgium; UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland; Department of Archaeology, School of Archaeology, Geography and Environmental Science, University of Reading, Whiteknights, PO Box 227, Reading, United Kingdom; Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, Baltzerstrasse 1+3, Bern, Switzerland
Recommended Citation:
Fankhauser A.,McDermott F.,Fleitmann D.. Episodic speleothem deposition tracks the terrestrial impact of millennial-scale last glacial climate variability in SW Ireland[J]. Quaternary Science Reviews,2016-01-01,152