气候变化领域集成服务门户(CCPortal): Impact of glacial-lake paleofloods on valley development since glacial termination II: A conundrum of hydrology and scale for the lowstand Brahmaputra-Jamuna paleovalley system

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DOI	10.1130/B31941.1
	Impact of glacial-lake paleofloods on valley development since glacial termination II: A conundrum of hydrology and scale for the lowstand Brahmaputra-Jamuna paleovalley system
	Pickering J.L.; Diamond M.S.; Goodbred S.L.; Grall C.; Martin J.M.; Palamenghi L.; Paola C.; Schwenk T.; Sincavage R.S.; Spieß V.
发表日期	2019
ISSN	167606
起始页码	58
结束页码	70
卷号	131 期号:2021-01-02
英文摘要	To better define the base of the Brahmaputra River paleovalley, we analyzed an extensive borehole data set from the subaerial Bengal delta and a 255-km-long multichannel seismic survey along the modern river. The data reveal that the paleovalley floor is defined by a gravel unit containing bouldersized clasts up to 30 cm in diameter, deposited after ca. 30 ka but before ca. 9 ka. Paleohydrology during that time and the previous glacial maximum was characterized by a weak monsoon and reduced river discharge, both of which are inconsistent with large valley formation. However, our work indicates that glacial-lake outburst floods sourced from the Tibetan reaches of the Brahmaputra were routed through the lowstand valley, producing megaflood-scale discharge capable of transporting gravel and cannibalizing the valley margins. The timing of these glacial-lake outburst flood-driven discharge events was coincident with valley development and explains the anomalously large width of the valley and basal gravel surface. Despite the underfit scale of Brahmaputra discharge following the last glacial period, a strengthening monsoon and high sediment discharge in the early Holocene subsequently contributed to the efficient infilling of the massive paleovalley by the mid-Holocene. In a sequence stratigraphic context, this work provides an example of a major unconformity that developed late in the eustatic cycle (i.e., during early transgression rather than an earlier, protracted response to sealevel lowering) and in response to a perturbation originating in the catchment instead of changing accommodation in the basin. As such, it represents a geologically instantaneous time surface that can be used as a marker for stratigraphic correlation but one that is not in phase with eustatic sea-level fall. © 2018 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184970
作者单位	Department of Earth and Environmental Science, Vanderbilt University, Nashville, TN 37235, United States; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, United States; Shell International Exploration and Production, Inc., Houston, TX 77082, United States; Faculty of Geosciences, University of Bremen, Bremen, 28359, Germany; Department of Earth Sciences and St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN 55455, United States; Shell International Exploration and Production, Inc., Houston, TX 77082, United States; Department of Atmospheric Sciences, University of Washington, Seattle, WA 98195, United States; Department of Geology, Radford University, Radford, VA 24142, United States
推荐引用方式 GB/T 7714	Pickering J.L.,Diamond M.S.,Goodbred S.L.,et al. Impact of glacial-lake paleofloods on valley development since glacial termination II: A conundrum of hydrology and scale for the lowstand Brahmaputra-Jamuna paleovalley system[J],2019,131(2021-01-02).
APA	Pickering J.L..,Diamond M.S..,Goodbred S.L..,Grall C..,Martin J.M..,...&Spieß V..(2019).Impact of glacial-lake paleofloods on valley development since glacial termination II: A conundrum of hydrology and scale for the lowstand Brahmaputra-Jamuna paleovalley system.Bulletin of the Geological Society of America,131(2021-01-02).
MLA	Pickering J.L.,et al."Impact of glacial-lake paleofloods on valley development since glacial termination II: A conundrum of hydrology and scale for the lowstand Brahmaputra-Jamuna paleovalley system".Bulletin of the Geological Society of America 131.2021-01-02(2019).