DOI: 10.1007/s00531-013-0968-3
Scopus记录号: 2-s2.0-84894286675
论文题名: Umbrella structure and channel-wall stoping in the Cambrian St. Roch Formation, Quebec Appalachians: Significance for particle support mechanisms and turbulence development in hyper-concentrated sediment gravity flows
作者: Hesse R. ; Fong C.
刊名: International Journal of Earth Sciences
ISSN: 14373254
出版年: 2014
卷: 103, 期: 2 起始页码: 509
结束页码: 518
语种: 英语
英文关键词: Channel-wall stoping
; Dispersive pressure
; High- to hyper-concentrated sediment gravity flows
; Laminar sheared layer
; Particle support mechanism
; Platy-boulder-bearing pebble conglomerate
; Turbulence evolution with time
; Umbrella structure
英文摘要: Umbrella structure is a newly recognized sedimentary structure associated with large platy clasts in resedimented boulder-bearing pebble conglomerate with a sandy matrix. It consists of a sand rim that lacks pebbles on parts or the entire underside of platy boulders, whereas on the upper side, pebbles are in direct contact with the boulders. The depositing processes were high- to hyper-concentrated sediment gravity flows in a submarine channel or canyon on the Cambrian continental slope of North America bordering the Iapetus Ocean. The structure occurs predominantly where clasts dip moderately in the down-current direction. Based on the association of the structure with slightly forward dipping slabs, it is proposed that these down-current dipping slabs may have been in the process of counter-clockwise rotation that was aborted and may have generated a pressure shadow on the underside enabling the inrush of fluid and the infiltration of sand into the anomalous low-pressure zone. The structure has implications for particle support mechanisms in high- to hyper-concentrated sedimentary gravity flows, in that it redirects attention to the much debated mechanism of dispersive pressure and alternatives. It provides an observable sediment structure that supports dispersive pressure which so far depended on experimental evidence and theoretical arguments alone. Vrolijk and Southard's (1997) concept of a 'laminar sheared layer' is here for the first time interpreted as having an upward-moving 'free-surface' layer effect during deposition from hyper-concentrated flows. Channel-wall stoping involves unlithified turbiditic spillover sand in the levee sediment of the canyon wall that was washed out by the upper diluted parts of the high-concentration flows coming down the channel and leaving a niche in the wall that was filled with coarser channel-axis facies by the same flow (or later flows) when its aggradation reached the level of the niche. The contact between turbidite and pebble conglomerate occurs now more than 2 m laterally into the exposed channel wall. Channel-wall stoping tracks turbulence development in hyper-concentrated gravity flows. © 2013 Springer-Verlag Berlin Heidelberg. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84894286675&doi=10.1007%2fs00531-013-0968-3&partnerID=40&md5=0e9b88a78604aa25d2f83499e86bd919
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/70462
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, QC, H3A 2A7, Canada; Department of Geo- and Environmental Sciences, Ludwig Maximilians University, Munich, 80333 Munich, Germany; Apt. 102, No.16, Lane 3297, Hongmei Road, Shanghai, 201103, China
Recommended Citation:
Hesse R.,Fong C.. Umbrella structure and channel-wall stoping in the Cambrian St. Roch Formation, Quebec Appalachians: Significance for particle support mechanisms and turbulence development in hyper-concentrated sediment gravity flows[J]. International Journal of Earth Sciences,2014-01-01,103(2)