Size, shape and spatial arrangement of mega-scale glacial lineations from a large and diverse dataset
Size, shape and spatial arrangement of mega-scale glacial lineations from a large and diverse dataset
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来自大型且多样化的数据集的巨型冰川线的大小、形状和空间排列
DOI：
10.1002/esp.3532
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发表时间：
2014
影响因子：
3.3
通讯作者：
Spagnolo M
中科院分区：
文献类型：
--
作者：
Spagnolo M
大尺度冰川线条(MSGL)是冰川河床上的一种典型地貌。解决它们的形成之谜是理解冰如何与其床相互作用以及这反过来如何影响冰流动力学的关键。然而，对这一地貌的大小、形状和空间安排的全面和详细的描述，可能有助于检验和完善形成理论，在很大程度上是缺乏的。本文对来自8个古冰流环境的4043个MSGL进行了详细的形态分析和比较：3个近海(挪威和南极洲)，4个陆上(加拿大)，以及1个来自西南极现代冰流下的MSGL。MSGL的长度比以前提出的要短(模式1000-2000 m；中位数2892 m)，并且它们在冰川床上的不同位置开始和终止。它们的空间排列显示出一种特殊的平行一致性(所有测绘的MSGL中80%的方位距平均值在5°以内)和相当恒定的横向间距(模式200-300 m；中位数330 m)的格局，我们将其解释为MSGL是一种空间自组织现象。结果表明，无论是在冰床内部还是在不同冰川床之间，MSGL的大小、形状和空间分布都是一致的。我们认为这是一种共同的形成机制的结果，这种机制在很大程度上对当地因素不敏感。尽管MSGL的伸长(模式6-8；中位数12.2)通常高于鼓状地貌，但这些值与它们的宽度(模式100-200 m；中位数268 m)重叠，这表明这两个地貌是形态连续体的一部分，可能具有相似的起源。我们将它们的形态计量学与MSGL形成的沟槽-犁沟和沟槽不稳定性理论所作的明确预测进行了比较。尽管后者是最相容的，但两者都不能完全得到观察结果的支持。©2014作者。地球表面过程和地貌由John Wiley&Sons Ltd.出版。
Mega‐scale glacial lineations (MSGLs) are a characteristic landform on ice stream beds. Solving the puzzle of their formation is key to understanding how ice interacts with its bed and how this, in turn, influences the dynamics of ice streams. However, a comprehensive and detailed characterization of this landform's size, shape and spatial arrangement, which might serve to test and refine formational theories, is largely lacking. This paper presents a detailed morphometric analysis and comparison of 4043 MSGLs from eight palaeo‐ice stream settings: three offshore (Norway and Antarctica), four onshore (Canada), and one from under a modern ice stream in West Antarctica. The length of MSGLs is lower than previously suggested (mode 1000–2000 m; median 2892 m), and they initiate and terminate at various locations on an ice stream bed. Their spatial arrangement reveals a pattern that is characterized by an exceptional parallel conformity (80% of all mapped MSGLs have an azimuth within 5° from the mean values), and a fairly constant lateral spacing (mode 200–300 m; median 330 m), which we interpret as an indication that MSGLs are a spatially self‐organized phenomenon. Results show that size, shape and spatial arrangement of MSGLs are consistent both within and also generally between different ice stream beds. We suggest this results from a common mechanism of formation, which is largely insensitive to local factors. Although the elongation of MSGLs (mode 6–8; median 12.2) is typically higher than features described as drumlins, these values and those of their width (mode 100–200 m; median 268 m) overlap, which suggests the two landforms are part of a morphological continuum and may share a similar origin. We compare their morphometry with explicit predictions made by the groove‐ploughing and rilling instability theories of MSGL formation. Although the latter was most compatible, neither is fully supported by observations. © 2014 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.