Switching of a paleo-ice stream in northwest Svalbard
Switching of a paleo-ice stream in northwest Svalbard
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DOI：
10.1016/j.quascirev.2011.03.013
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发表时间：
2011-06
影响因子：
4
通讯作者：
S. Sarkar;C. Berndt;A. Chabert;D. Masson;T. Minshull;G. Westbrook
中科院分区：
文献类型：
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作者：
S. Sarkar;C. Berndt;A. Chabert;D. Masson;T. Minshull;G. Westbrook
冰流是冰盖的快速流动区域，可以释放大量的冰。斯瓦尔巴特群岛西部冰川边缘由几个跨陆架槽组成，这些槽是上新世-更新世冰川作用期间的前冰流排泄通道。通过对斯瓦尔巴群岛西部和西北部边缘的高分辨率多波束条带测深数据和多条高分辨率二维反射地震剖面的综合分析，我们推断了冰流流动方向和冰流沉积的冰川碎片的沉积中心。外边缘。我们的研究结果表明，斯瓦尔巴群岛的西北边缘经历了一个主要的冰流切换。通过与区域地震地层学资料的对比，以及与ODP 911和ODP 986的对比，我们发现，在北方半球初始冷却期（2.8- 2.6Ma），首先发育了一条向西北方向流动的冰流。冰流流向的开关，以今天的Kongsfjorden跨陆架槽发生在冰川作用在1.5Ma或可能以后在一个密集的主要冰川作用阶段被称为'中更新世革命'开始于1.0Ma。地震和测深数据表明，开关是突然的，而不是渐进的，我们把它归因于达到一个临界点时，斯瓦尔巴冰盖的增长已经达到了临界厚度和冰盖可以克服地形障碍。
Ice streams are the fast-flowing zones of ice sheets that can discharge a large flux of ice. The glaciated western Svalbard margin consists of several cross-shelf troughs which are the former ice stream drainage pathways during the Pliocene–Pleistocene glaciations. From an integrated analysis of high-resolution multibeam swath-bathymetric data and several high-resolution two-dimensional reflection seismic profiles across the western and northwestern Svalbard margin we infer the ice stream flow directions and the deposition centres of glacial debris that the ice streams deposited on the outer margin. Our results show that the northwestern margin of Svalbard experienced a switching of a major ice stream. Based on correlation with the regional seismic stratigraphy as well as the results from ODP 911 on Yermak Plateau and ODP 986 farther south on the western margin of Spitsbergen, off Van Mijenfjord, we find that first a northwestward flowing ice stream developed during initial northern hemispheric cooling (starting ∼2.8–2.6 Ma). A switch in ice stream flow direction to the present-day Kongsfjorden cross-shelf trough took place during a glaciation at ∼1.5 Ma or probably later during an intensive major glaciation phase known as the ‘Mid-Pleistocene Revolution’ starting at ∼1.0 Ma. The seismic and bathymetric data suggest that the switch was abrupt rather than gradual and we attribute it to the reaching of a tipping point when growth of the Svalbard ice sheet had reached a critical thickness and the ice sheet could overcome a topographic barrier.