气候变化领域集成服务门户(CCPortal): Glacial overdeepenings in the Swiss Alps and foreland: Spatial distribution and morphometrics

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DOI	10.1016/j.quascirev.2020.106483
	Glacial overdeepenings in the Swiss Alps and foreland: Spatial distribution and morphometrics
	Magrani F.; Valla P.G.; Gribenski N.; Serra E.
发表日期	2020
ISSN	0277-3791
卷号	243
英文摘要	Overdeepenings (ODs) are erosional features that have been excavated below the regional sea/fluvial base level to produce closed topographic basins. Accessing bedrock topography and OD volume is often challenging. Hence, despite constituting major landscape features and being widespread in (paleo-)glaciated regions, ODs have been overlooked and the subglacial processes involved in their evolution have remained debated. In the Swiss Alpine foreland and valleys, ODs are commonly found filled with water or large volumes of sediment. Using a GIS-Matlab approach based on topographic datasets and bedrock contour-curves, we mapped the spatial distribution of ODs in Switzerland and adjacent areas in the ice-free Alpine areas. The majority of the mapped ODs occurs in very-low bedrock erosional resistance, where ODs are larger, wider and shallower than in medium to high bedrock erosional resistance domains, evidencing a strong lithological control on OD geometry. Longitudinal asymmetry and hypsometric integral suggest a dominance of quarrying during OD evolution and, for selected glacial catchments, headward erosion propagation or high sediment evacuation efficiency. OD surface data (surface and length) can be tentatively used for extracting OD subsurface metrics (depths, nested valleys and first-order volume estimates). Our data seem to indicate that ODs may initiate as multiple small nested valleys and progress to a single and connected depression. Transversal cross-sections also suggest a negative feedback between the erosion potential for deep carving and the presence of low-resistance bedrock, where subglacial meltwater infiltration could have played a key role in OD evolution. Although insightful relationships have been evidenced for ODs in the Swiss Alps and foreland, we have also observed a high spatial variability in key OD metrics such as surface area and depth. This results in general (first-order) interpretations at regional scale, but currently prevent to quantitatively constrain physical subglacial processes at their origin. Comparisons with existing OD datasets under present-day ice (Greenland, Antarctica and modern Swiss glaciers) place our results in a broader context and allow a step forward in our understanding of the complex patterns and mechanisms of (sub-)glacial erosion and resulting landforms. © 2020 The Authors
英文关键词	(Sub-)glacial processes; Glacial overdeepenings; Morphometrics; Patterns of glacial erosion; Swiss alps and foreland
语种	英语
scopus关键词	Catchments; Feedback; Glacial geology; Landforms; Lithology; Spatial distribution; Topography; Erosion potentials; Glacial erosion; Landscape feature; Sediment evacuation; Spatial variability; Subglacial meltwater; Subglacial process; Topographic datasets; Erosion; alpine environment; bedrock; catchment; GIS; glacial erosion; morphometry; spatial distribution; spatial variation; subglacial environment; valley; Alps; Antarctica; Arctic; Greenland; Switzerland
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/151376
作者单位	Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, Baltzerstrasse 1, Bern, CH-3012, Switzerland; Institute of Earth Sciences (ISTerre), Université Grenoble Alps, Université Savoie Mont Blanc, CNRS, IRD, IFSTAR, Grenoble, 38000, France
推荐引用方式 GB/T 7714	Magrani F.,Valla P.G.,Gribenski N.,et al. Glacial overdeepenings in the Swiss Alps and foreland: Spatial distribution and morphometrics[J],2020,243.
APA	Magrani F.,Valla P.G.,Gribenski N.,&Serra E..(2020).Glacial overdeepenings in the Swiss Alps and foreland: Spatial distribution and morphometrics.Quaternary Science Reviews,243.
MLA	Magrani F.,et al."Glacial overdeepenings in the Swiss Alps and foreland: Spatial distribution and morphometrics".Quaternary Science Reviews 243(2020).