A new concept for glacial geological investigations of surges, based on High-Arctic examples (Svalbard)
A new concept for glacial geological investigations of surges, based on High-Arctic examples (Svalbard)
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DOI：
10.1016/j.quascirev.2015.11.009
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发表时间：
2016-01
影响因子：
4
通讯作者：
I. Lønne
中科院分区：
文献类型：
--
作者：
I. Lønne
斯瓦尔巴群岛是研究冰川涌流的一个关键地区，在这个地区进行了近两个世纪的实地观测。研究表明，浪涌的过程和与之相关的地貌形成受到盆地因素的强烈影响，所涉及的各种变量可能妨碍解释和比较。在对斯瓦尔巴群岛冰川涌流研究综述的基础上，提出了一种结合冰流、冰锋运动和形态地层学的冰川地质调查新概念。该概念由以下四个要素组成：1)基于接收盆地的结构和特征进行分类，2)将涌浪周期划分为六个阶段，3)形态制图指南，以及4)使用异位地层方法解释冰锋运动。在此背景下，活动性阶段的划定至关重要，其中包括终点运动的历史，并确认了四类主要的接收盆地。它们分别是(A)基底可变形的陆相盆地，(B)基底变形差的陆相盆地，(C)浅水盆地，(D)深水盆地。将前冰期冰碛（同涌浪期）、冰上冰碛（涌浪期后）以及与涌浪期（I-VI期）相关的融水痕迹信息耦合起来，重建了冰锋运动历史。该方法揭示了活跃期的结束与最大冰锋位置、最大冰碛范围和最年轻前冰碛三个形态要素之间的关键关系，这三个形态要素在a - d各盆地中都是独特的。因此，该概念是绘制活跃期和活跃期持续时间的一种新颖而更精确的方法，如Fridtjovbreen长达12年的涌浪所示，其中阶段I为30个月（开始），阶段II为54个月（冰锋推进），阶段III为12个月（静止），阶段IV为48个月（活跃流期间的退缩）。自2002年以来，该冰川一直处于静止阶段（V/VI阶段）。
Svalbard is a key area for the investigation of glacial surges, and almost two centuries worth of field observations exists from this region. Studies have shown that the course of a surge and the associated formation of landforms are strongly influenced by basinal factors, and that the broad range of variables involved can hamper interpretations and comparisons. Based on a review of surges in Svalbard, a new concept for glacial geological investigations has been developed that combines ice-flows, ice-front movements, and morphostratigraphy. The concept is comprised of the following four elements: 1) classification based on the configuration and characteristics of the receiving basin, 2) division of the surge cycle into six stages, 3) guidelines for morphological mapping, and 4) use of an allostratigraphic approach for interpreting ice-front movements. In this context, delineation of the active phase is critical, which include the history of terminus movements, and four main categories of receiving basins are recognized. These are (A) terrestrial basins with deformable substrates, (B) terrestrial basins with poorly deformable substrates, (C) shallow water basins, and (D) deep water basins. The ice-front movement history is reconstructed by coupling information from the proglacial moraines (syn-surge), the supraglacial moraines (post-surge), and the associated traces of meltwater to the surge stages (I–VI). This approach has revealed a critical relationship between the termination of the active phase and three morphological elements, namely, the maximum ice-front position, the maximum moraine extent and the youngest proglacial moraine, which are unique for each of the basins A–D. The concept is thus a novel and more precise approach for mapping the active phase and the active phase duration, as shown by the ∼12-year long surge of Fridtjovbreen, where stage I was 30 months (inception), stage II was 54 months (ice-front advance), stage III was 12 months (stillstand), and stage IV was 48 months (retreat during active flow). The glacier has been in quiescent phase (stages V/VI) since 2002.