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New constraints on the last deglaciation of the Cordilleran Ice Sheet in coastal Southeast Alaska
Quaternary Research ( IF 2.3 ) Pub Date : 2020-05-14 , DOI: 10.1017/qua.2020.32
Alia J. Lesnek , Jason P. Briner , James F. Baichtal , Alex S. Lyles

Understanding marine-terminating ice sheet response to past climate transitions provides valuable long-term context for observations of modern ice sheet change. Here, we reconstruct the last deglaciation of marine-terminating Cordilleran Ice Sheet (CIS) margins in Southeast Alaska and explore potential forcings of western CIS retreat. We combine 27 new cosmogenic 10Be exposure ages, 13 recently published 10Be ages, and 25 new 14C ages from raised marine sediments to constrain CIS recession. Retreat from the outer coast was underway by 17 ka, and the inner fjords and sounds were ice-free by 15 ka. After 15 ka, the western margin of the CIS became primarily land-terminating and alpine glaciers disappeared from the outer coast. Isolated alpine glaciers may have persisted in high inland peaks until the early Holocene. Our results suggest that the most rapid phase of CIS retreat along the Pacific coast occurred between ~17 and 15 ka. This retreat was likely driven by processes operating at the ice-ocean interface, including sea level rise and ocean warming. CIS recession after ~15 ka occurred during a time of climatic amelioration in this region, when both ocean and air temperatures increased. These data highlight the sensitivity of marine-terminating CIS regions to deglacial climate change.

中文翻译:

阿拉斯加东南沿海科迪勒拉冰盖末次消融的新限制

了解终止海洋的冰盖对过去气候转变的反应为观察现代冰盖变化提供了宝贵的长期背景。在这里,我们重建了阿拉斯加东南部终止海洋的科迪勒拉冰盖 (CIS) 边缘的最后一次冰川消退,并探索了西部独联体撤退的潜在强迫。我们结合了 27 个新的宇宙起源10是曝光年龄,13最近出版10年龄和 25 新14来自升高的海洋沉积物的 C 年龄限制了独联体的衰退。17 ka 时开始从外海岸撤退,15 ka 时内峡湾和声音已无冰。15 ka 后,独联体西部边缘主要成为陆地终结点,高山冰川从外海岸消失。孤立的高山冰川可能一直存在于内陆高山,直到全新世早期。我们的研究结果表明,太平洋沿岸独联体撤退的最快阶段发生在~17 到 15 ka 之间。这种撤退可能是由在冰海界面上运行的过程驱动的,包括海平面上升和海洋变暖。大约 15 ka 之后的独联体衰退发生在该地区气候改善的时期,当时海洋和气温都升高了。
更新日期:2020-05-14
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