Extent and deglacial chronology of the last British-Irish Ice Sheet: implications of exposure dating using cosmogenic isotopes
Extent and deglacial chronology of the last British-Irish Ice Sheet: implications of exposure dating using cosmogenic isotopes
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DOI：
10.1002/jqs.1310
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发表时间：
2010-05-01
影响因子：
2.3
通讯作者：
Ballantyne, Colin K.
中科院分区：
文献类型：
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作者：
Ballantyne, Colin K.
超过160 Be-10和Cl-36暴露年龄有关的范围和年代的最后英属爱尔兰冰盖（BIIS）的批判性审查。尽管暴露年龄的使用固有的不确定性，这种方法已经证明，在末次盛冰期（LGM;约。26-21 ka），BUS延伸到苏格兰和整个（或几乎整个）爱尔兰的所有低地，与最近的模型描述的最后一个BIIS延伸到大西洋陆架边缘一致。苏格兰西北部和爱尔兰山区的纵倾线以上的高水平地点获得的所有暴露年龄早于末次冰期。这一发现证实，这些地区的高原没有受到严重的冰川侵蚀，可能是在冷基冰川冰的保护下，这些冰川冰仍然冻结在下面的基底上。根据冰消年代学，爱尔兰海南部海盆可能在19-18 ka之间发生了冰消作用，而爱尔兰和苏格兰东北部的低地早于约2000年就发生了广泛的冰消作用。14.5 ka.苏格兰西北部低地的冰盖显然在14.0 ka后持续存在，这表明在晚冰期间冰期（约2000年），有利位置的冰仍然存在。14.5- 12.9ka）。尝试重新测定时间的结果好坏参半。在苏格兰西北部的韦斯特罗斯再推进最初可追溯到公元前。16.3卡，但最近的研究表明，一个更年轻的年龄（约。14.0- 13.5ka）。暴露年龄表明一个长期的stillstand在冰盖退缩在Cairngorms约。14.5- 14.0ka与冰后期岩石滑坡年龄和基底放射性碳年龄相矛盾，表明冰消期早于约14.5 - 14.0ka。15.5-15.0 ka。曝光测年已成功地用于确认洛赫湖体育场I（约。12.9-11.5 ka）的年龄，并限制了当时西格兰扁山脉冰帽的最低海拔。版权所有（C）2009约翰威利父子有限公司
Over 160 Be-10 and Cl-36 exposure ages pertaining to the extent and chronology of the last British Irish Ice Sheet (BIIS) are critically reviewed. Despite uncertainties inherent in the use of exposure ages, this approach has demonstrated that at the Last Glacial Maximum (LGM; ca. 26-21 ka) the BUS extended over all low ground in Scotland and all (or almost all) of Ireland, consistent with recent models depicting extension of the last BIIS to the Atlantic shelf edge. All exposure ages obtained for high-level sites above trimlines on the mountains of northwestern Scotland and Ireland pre-date the LGM. This finding confirms that high plateaux in these areas escaped significant glacial erosion, probably under a protective cover of cold-based glacier ice that remained frozen to the underlying substrate. In terms of deglaciation chronology, the southern Irish Sea basin was probably cleglaciated by 19-18 ka, with extensive deglaciation of low ground in Ireland and northeastern Scotland prior to ca. 14.5 ka. Ice cover on low ground in northwestern Scotland apparently persisted after 14.0 ka, suggesting survival of ice in favourable locations during the Lateglacial Interstade (ca. 14.5-12.9 ka). Attempts to date readvances have had mixed success. The Wester Ross Readvance in northwestern Scotland was initially dated to ca. 16.3 ka, but more recent research implies a much younger age (ca. 14.0-13.5 ka). Exposure ages indicating a prolonged stillstand during ice sheet retreat in the Cairngorms at ca. 14.5-14.0 ka conflict with ages obtained on postglacial rockslides and basal radiocarbon dates, which indicate deglaciation before ca. 15.5-15.0 ka. Exposure dating has been successfully employed to confirm a Loch Lomond Stadia I (ca. 12.9-11.5 ka) age for moraines in several mountain areas, and to constrain the minimum altitude of the ice cap that extended over the Western Grampians at that time. Copyright (C) 2009 John Wiley & Sons, Ltd.