Microstructures of sediment flow deposits and subglacial sediments: a comparison
Microstructures of sediment flow deposits and subglacial sediments: a comparison
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泥沙流沉积物和冰下沉积物的微观结构：比较
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
R. Alley
中科院分区：
文献类型：
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作者：
M. Lachniet;G. Larson;D. Lawson;E. Evenson;R. Alley
冰川沉积的微结构分析最近已被用作确定沉积物成因的研究工具。然而，在已知来源的沉积物中出现的微结构还没有充分的证据，这阻碍了我们自信地解释来源不明的沉积物中的微结构的能力。我们的目标是对阿拉斯加马塔努斯卡冰川现代沉积物流沉积和伴生沉积物的微结构进行校准研究，并评估在亚冰川变形沉积物中发现的微结构的共性程度。泥沙流沉积中的微结构可作为泥沙运移、沉积和/或沉积后过程的结果，并与源流的粘性状态有关。脆性变形过程中形成的特征微观结构包括剪切、断层和角砾岩；韧性变形过程中形成的微观结构包括褶皱、压力阴影、围绕‘核心’岩石的碎屑重定向、细层、基底剪切带、叠瓦性和流动组构。其他微构造包括流体逃逸和注入构造、碎屑晕和裂隙。我们的对比结果表明，沉积物流动沉积与亚冰川变形沉积物具有许多共同的微观结构。
Microstructural analysis of glacial deposits has recently been used as a research tool to determine sediment genesis. However, the occurrence of microstructures in deposits of known origin has not been sufficiently documented, hindering our ability to confidently interpret microstructures in sediments of unknown origin. Our objective is to present a calibration study of microstructures of recent sediment flow deposits and associated sediments from the Matanuska Glacier, Alaska, and to evaluate the degree of commonality with micro‐structures found in subglacially deformed sediments. Microstructures in sediment flow deposits can be formed as a result of sediment transport, deposition, and/or post‐depositional processes, and are related to the viscosity regime of the source flow. Characteristic microstructures formed during brittle deformation include shears, faults, and brecciation; microstructures formed during ductile deformation include folds, pressure shadows, reorientation of clasts around a ‘core’ stone, fine laminations, basal shear zones, imbrication, and flow fabrics. Other microstructures include fluid escape and injection structures, clast haloes, and fissility. The results of our comparison suggest that sediment flow deposits share many microstructures in common with subglacially deformed sediments.