Dating of raised marine and lacustrine deposits in east Greenland using beryllium‐10 depth profiles and implications for estimates of subglacial erosion
Dating of raised marine and lacustrine deposits in east Greenland using beryllium‐10 depth profiles and implications for estimates of subglacial erosion
复制标题
使用铍-10深度剖面对格陵兰岛东部凸起的海洋和湖泊沉积物进行年代测定及其对冰下侵蚀估计的影响
DOI：
10.1002/jqs.1380
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发表时间：
2010
影响因子：
2.3
通讯作者：
T. Lowell
中科院分区：
文献类型：
--
作者：
B. Goehring;M. Kelly;J. Schaefer;R. Finkel;T. Lowell
在此，我们将应用于末次冰期冰缘海洋和湖泊三角洲的¹⁰Be深度剖面技术，以及格陵兰岛东部斯科斯比松地区相关地貌的漂砾暴露测年相结合，以确定地表年龄和宇宙成因核素继承量。斯科斯比松北部一个冰缘三角洲的漂砾年龄呈现出极地地区典型的离散性，平均年龄为12.8±0.5千年，比我们从三个深度剖面获得的平均剖面地表年龄10.9±0.7千年以及基于放射性碳的估算结果大约老2千年。另一方面，斯科斯比松南部一组冰碛的漂砾暴露年龄在极地地区表现出极好的内部一致性，平均年龄为11.6±0.2千年。相应冰缘三角洲的剖面地表年龄为8.1±0.9千年，而另一个三角洲的年龄为10.0±0.4千年。所有深度剖面所测的¹⁰Be继承浓度内部一致，介于地表浓度的10% - 20%之间，这表明斯科斯比松地区存在区域宇宙成因继承信号。基于剖面继承浓度，我们探究了格陵兰冰盖下集水区平均基岩侵蚀的一级情况，得出末次冰期旋回期间总侵蚀量约为2 - 30米的估算值。版权所有© 2010约翰威立父子有限公司
Here we combine 10Be depth profile techniques applied to late glacial ice‐contact marine and lacustrine deltas, as well as boulder exposure dating of associated features in the Scoresby Sound region, east Greenland, to determine both the surface age and the magnitude of cosmogenic nuclide inheritance. Boulder ages from an ice‐contact delta in northern Scoresby Sund show scatter typical of polar regions and yield an average age of 12.8 ± 0.5 ka – about 2 ka older than both our average profile surface age of 10.9 ± 0.7 ka from three depth profiles and a radiocarbon‐based estimate. On the other hand, boulder exposure ages from a set of moraines in southern Scoresby Sund show excellent internal consistency for polar regions and yield an average age of 11.6 ± 0.2 ka. The profile surface age from a corresponding ice‐contact delta is 8.1 ± 0.9 ka, while a second delta yields an age of 10.0 ± 0.4 ka. Measured 10Be inheritance concentrations from all depth profiles are internally consistent and are between 10% and 20% of the surface concentrations, suggesting a regional cosmogenic inheritance signal for the Scoresby Sound landscape. Based on the profile inheritance concentrations, we explore the first‐order catchment‐averaged bedrock erosion under the Greenland ice sheet, yielding estimates of total erosion during the last glacial cycle of the order of 2–30 m. Copyright © 2010 John Wiley & Sons, Ltd.