DOI: 10.1016/j.quascirev.2016.11.018
论文题名: Repeated sedimentation and exposure of glacial Lake Missoula sediments: A lake-level history at Garden Gulch, Montana, USA
作者: Smith L.N.
刊名: Quaternary Science Reviews
出版年: 2017
卷: 155 起始页码: 114
结束页码: 126
语种: 英语
英文关键词: Active-layer wedge
; Geomorphology
; Glacial Lake Missoula
; North America
; Periglacial
; Quaternary
Scopus关键词: Geomorphology
; Glacial geology
; Gravel
; Hydraulic structures
; Levees
; Sediments
; Silt
; Active Layer
; Glacial Lake Missoula
; North America
; Periglacial
; Quaternary
; Lakes
英文摘要: Glaciolacustrine sediments record lake transgression, regression, and subaerial modification of the silty lake-bottom of glacial Lake Missoula in the Clark Fork River valley. The sequence preserved at Garden Gulch, MT documents lake-level fluctuations at >65% of its full-pool volume. Twelve sedimentary cycles fine upwards from (1) very fine-grained sandy silt to (2) silt with climbing ripples to (3) rhythmically laminated silt and some clay. The cycles are fine-grained turbidites capped locally by thin layers of angular gravel derived from local bedrock outcrops. The gravels appear to be the toes of mass wasting lobes carried onto the exposed lakebed surface during repeated lake-level lowerings. Periglacial wedges, small rotational faults, involutions, and clastic dikes deform the tops of eleven cycles. The wedges are 10–30 cm wide, penetrate 30–70 cm deep, are spaced <1 m apart, and contain vertically oriented gravel and massive to laminated sediment. Wedges split and taper in plan view. A few thin silt-filled dikes, which branch and taper downwards from wedges, are interpreted as filled frost cracks. One 10–20 cm-wide sand-filled dike protrudes upward from a sand bed; it is interpreted as a liquefaction feature consistent with a filling and draining lake. The deformed cycle tops preserve evidence of periglacial cold, subaerial exposure, seasonal frost heave, and the incipient formation of sorted polygons. The lowest five cycles are thicker and display more periglacial modification at their tops than the upper seven cycles. The Garden Gulch section may represent as few as seven and as many as twelve substantial fillings and partial to complete drainings of glacial Lake Missoula. © 2016 Elsevier Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59356
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geological Engineering, Montana Tech of The University of Montana, 1300 W. Park St., Butte, MT, United States
Recommended Citation:
Smith L.N.. Repeated sedimentation and exposure of glacial Lake Missoula sediments: A lake-level history at Garden Gulch, Montana, USA[J]. Quaternary Science Reviews,2017-01-01,155