Ice cap erosion patterns from bedrock 10Be and 26Al, southeastern Tibetan Plateau
Ice cap erosion patterns from bedrock 10Be and 26Al, southeastern Tibetan Plateau
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DOI：
10.1002/esp.4544
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发表时间：
2018-12
影响因子：
3.3
通讯作者：
P. Fu;A. Stroeven;J. Harbor;J. Heyman;C. Hättestrand;M. Caffee
中科院分区：
文献类型：
--
作者：
P. Fu;A. Stroeven;J. Harbor;J. Heyman;C. Hättestrand;M. Caffee
冰川侵蚀的定量化有助于我们理解高海拔和高纬度地区的景观演变和地形地貌的产生。结合10 Be和26 Al原位分析的基岩，巨石，河砂样品，地貌制图，和实地调查，我们研究了冰川侵蚀模式的前冰帽在沙鲁里山的青藏高原东南部。总体地貌模式显示了在末次冰期前（末次盛冰期）冰川作用期间，4000平方公里的冰盖产生的景观改造的带状模式，而测年结果和高原表面的地貌意味着末次盛冰期冰盖进一步将冲刷的地形改造成不同的区域。模拟的冰川侵蚀深度为0-0.38米每100万年基岩样品位于靠近LGM冰盖的西部边缘，表明有限的侵蚀之前LGM和晚冰期冰碛沉积。在末次冰期冰帽边缘区附近存在一个强烈的侵蚀带，基岩样品的模拟冰川侵蚀深度>2.23 m/100 ka。模拟的冰川侵蚀深度为0-1.77米每100万年从样品收集的沿着边缘的中央高地，确认存在一个中间侵蚀区之间的中央高地和强侵蚀区。在河流砂样品中显着的核素遗传冲刷高原表面上的盆地也表明在末次冰期的限制冰川侵蚀。我们的研究第一次为青藏高原非侵蚀性冰下的冰川地貌的保存提供了明确的证据。由于冰川侵蚀强度的模式在很大程度上是由基底热制度驱动的，我们的研究结果证实了早期的推断，从地貌的同心基底热模式海子山冰帽在末次盛冰期。© 2018约翰威利父子有限公司
Quantifying glacial erosion contributes to our understanding of landscape evolution and topographic relief production in high altitude and high latitude areas. Combining in situ 10Be and 26Al analysis of bedrock, boulder, and river sand samples, geomorphological mapping, and field investigations, we examine glacial erosion patterns of former ice caps in the Shaluli Shan of the southeastern Tibetan Plateau. The general landform pattern shows a zonal pattern of landscape modification produced by ice caps of up to 4000 km2 during pre‐LGM (Last Glacial Maximum) glaciations, while the dating results and landforms on the plateau surface imply that the LGM ice cap further modified the scoured terrain into different zones. Modeled glacial erosion depth of 0–0.38 m per 100 ka bedrock sample located close to the western margin of the LGM ice cap, indicates limited erosion prior to LGM and Late Glacial moraine deposition. A strong erosion zone exists proximal to the LGM ice cap marginal zone, indicated by modeled glacial erosion depth >2.23 m per 100 ka from bedrock samples. Modeled glacial erosion depths of 0–1.77 m per 100 ka from samples collected along the edge of a central upland, confirm the presence of a zone of intermediate erosion in‐between the central upland and the strong erosion zone. Significant nuclide inheritance in river sand samples from basins on the scoured plateau surface also indicate restricted glacial erosion during the last glaciation. Our study, for the first time, shows clear evidence for preservation of glacial landforms formed during previous glaciations under non‐erosive ice on the Tibetan Plateau. As patterns of glacial erosion intensity are largely driven by the basal thermal regime, our results confirm earlier inferences from geomorphology for a concentric basal thermal pattern for the Haizishan ice cap during the LGM. © 2018 John Wiley & Sons, Ltd.