气候变化领域集成服务门户(CCPortal): A detailed lake-level reconstruction shows evidence for two abrupt lake drawdowns in the late-stage history of the eastern Lake Agassiz-Ojibway basin

CCPortal

DOI	10.1016/j.quascirev.2020.106327
	A detailed lake-level reconstruction shows evidence for two abrupt lake drawdowns in the late-stage history of the eastern Lake Agassiz-Ojibway basin
	Godbout P.-M.; Roy M.; Veillette J.J.
发表日期	2020
ISSN	0277-3791
卷号	238
英文摘要	Glacial Lake Ojibway occupied large areas in northeastern Ontario and northwestern Quebec during the last deglaciation. Paleogeographic reconstructions depict Lake Ojibway and Lake Agassiz sharing a common water plane shortly before the final drainage of this lake ∼8200 years ago. However, the pre-drainage surface elevation and extent of this large coalesced lake is based on scattered raised shorelines in the Ojibway basin and poorly constrained geomorphological considerations, which convey large uncertainties in lake-level reconstructions and the attendant meltwater volume estimates used to assess the impact of this freshwater discharge. Here, we address this issue by using 3098 elevation measurements of shorelines mapped on a LiDAR digital terrain model covering a key area in the Ojibway basin. Our reconstruction is based on a GIS model integrating the paleotopography, which reinforces correlation of shorelines and the identification of lake levels. The spatial distribution of shoreline-elevation data points shows well-defined clusters of shorelines aligned on distinct elevation ranges that delineate three widespread lake levels, which are separated by two intervals with atypically low number of shorelines reflecting abrupt lake drawdowns. This reconstruction considerably refines the sequence in the eastern (Ojibway) basin and shows evidence for a two-step drainage of Lake Agassiz-Ojibway. The results provide constraints on the magnitude of the lake-level drops and indicate that the pre-drainage surface-elevation of Lake Agassiz-Ojibway of earlier reconstructions was likely overestimated. Accordingly, the configuration and structure of this lake stage should be re-evaluated. To that effect, the new shoreline record provides an important framework for assessing late-stage changes in lake levels across the Agassiz-Ojibway basin, which is a critical step towards the production of realistic models depicting the drainage of this large lake. © 2020 Elsevier Ltd
英文关键词	8.2 ka cooling event; Drainage events; Lake Agassiz-Ojibway; Lake-level reconstruction; Last deglaciation; LiDAR DTM
语种	英语
scopus关键词	Catchments; Uncertainty analysis; Digital terrain model; Freshwater discharge; Last deglaciation; Paleogeographic reconstruction; Paleotopography; Realistic model; Surface elevations; Volume estimates; Lakes; digital terrain model; drawdown; GIS; glacial lake; lake level; last deglaciation; lidar; meltwater; paleotopography; reconstruction; shore (nonmarine); Agassiz; British Columbia; Canada; Lake Ojibway; Ontario [Canada]; Quebec [Canada]
来源期刊	Quaternary Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/151461
作者单位	Department of Earth and Atmospheric Sciences – GEOTOP Research Center, University of Quebec at Montreal, C.P. 8888, Succ. Centre-ville, Montreal, QC H3C 3P8, Canada; Geological Survey of Canada, Natural Resources Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada
推荐引用方式 GB/T 7714	Godbout P.-M.,Roy M.,Veillette J.J.. A detailed lake-level reconstruction shows evidence for two abrupt lake drawdowns in the late-stage history of the eastern Lake Agassiz-Ojibway basin[J],2020,238.
APA	Godbout P.-M.,Roy M.,&Veillette J.J..(2020).A detailed lake-level reconstruction shows evidence for two abrupt lake drawdowns in the late-stage history of the eastern Lake Agassiz-Ojibway basin.Quaternary Science Reviews,238.
MLA	Godbout P.-M.,et al."A detailed lake-level reconstruction shows evidence for two abrupt lake drawdowns in the late-stage history of the eastern Lake Agassiz-Ojibway basin".Quaternary Science Reviews 238(2020).