Stacking of Basal Debris Layers Without Bulk Freezing-on: Isotopic Evidence from West Greenland
Stacking of Basal Debris Layers Without Bulk Freezing-on: Isotopic Evidence from West Greenland
复制标题
没有大量冻结的基底碎片层的堆积：来自西格陵兰岛的同位素证据
DOI：
10.3189/s0022143000004536
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发表时间：
1989
影响因子：
3.4
通讯作者：
P. G. Knight
中科院分区：
文献类型：
--
作者：
P. G. Knight
摘要本文测试并证伪了这样一种理论：格陵兰冰盖边缘垂直堆叠的干净且充满碎片的冰层的厚厚序列的形成可以完全归因于冰层底部物质的简单冻结。Søndre Stramfjord附近冰盖边缘冰的δD和δ18O同位素分析表明，基底序列中富含碎屑和缺乏碎屑的元素具有不同的成因。虽然碎片带显示同位素分馏与冻结起源一致，但插入的干净冰层没有。干净冰层的同位素值与紧接在碎片带序列上方的含碎片冰和未改变的冰川冰没有区别，并且被与碎片带不同的过程夹带。碎片可能由于在河床冻结而被带走，但碎片带垂直堆积序列的形成必须归因于某种其他机制。
Abstract This paper tests and falsifies the theory that the development of thick sequences of vertically stacked clean and debris-laden ice layers at the margin of the Greenland ice sheet can be attributed solely to simple freezing-on of material at the bed. Isotopic analysis in δD and δ18O of ice from the ice-sheet margin near Søndre Stramfjord indicates that the debris-rich and debris-poor elements of the basal sequence have different origins. While the debris bands display isotopic fractionation consistent with a freezing origin, the intercalated clean ice layers do not. The clean ice layers have isotopic values indistinguishable from debris-bearing ice immediately above the debris-band sequence and from unaltered glacier ice, and are entrained by a different process from the debris bands. Debris may be entrained by freezing at the bed, but the development of a vertically stacked sequence of debris bands must be attributed to some other mechanism.