气候变化领域集成服务门户(CCPortal): Permafrost distribution and conditions at the headwalls of two receding glaciers (Schladming and Hallstatt glaciers) in the Dachstein Massif, Northern Calcareous Alps, Austria

CCPortal

DOI	10.5194/tc-14-1173-2020
	Permafrost distribution and conditions at the headwalls of two receding glaciers (Schladming and Hallstatt glaciers) in the Dachstein Massif, Northern Calcareous Alps, Austria
	Rode M.; Sass O.; Kellerer-Pirklbauer A.; Schnepfleitner H.; Gitschthaler C.
发表日期	2020
ISSN	19940416
起始页码	1173
结束页码	1186
卷号	14 期号:4
英文摘要	Permafrost distribution in rock walls surrounding receding glaciers is an important factor in rock stability and rock wall retreat. We investigated bedrock permafrost distribution in the Dachstein Massif, Austria, reaching up to 2995 m a.s.l. The occurrence, thickness and thermal regime of permafrost at this partly glaciated mountain massif are scarcely known. We applied a multi-method approach with continuous ground surface and near-surface temperature monitoring (GST), measurement of the bottom temperature of the winter snow cover (BTS), electrical resistivity tomography (ERT), airborne photogrammetry, topographic maps, visual observations, and field mapping. Our research focused on several steep rock walls consisting of massive limestone above receding glaciers exposed to different slope aspects at elevations between ca. 2600 and 2700 m a.s.l. We aimed to quantify the distribution and conditions of bedrock permafrost particularly at the transition zone between the present glacier surface and the adjacent rock walls. According to our ground temperature data, permafrost is mainly found at north-facing rock walls. At south-east-facing rock walls, permafrost is probable only in very favourable cold conditions at radiation-sheltered higher elevations (>2700 m a.s.l.). ERT measurements reveal high resistivities (>30 000 ω m) at ≥1.5 m depth at north-exposed slopes (highest values >100 kω m). Deducted from laboratory studies and additional small-scale ERT measurements, these values indicate permafrost existence. Permafrost bodies were found at several rock walls independent of investigated slope orientation; however, particularly large permafrost bodies were found at north-exposed sites. Furthermore, at vertical survey lines, a pronounced imprint of the former Little Ice Age (LIA) ice margin was detected. Resistivities above and below the LIA line are markedly different. At the LIA glacier surface, the highest resistivities and lowest active-layer thicknesses were observed. The active-layer thickness increases downslope from this zone. Permafrost below the LIA line could be due to permafrost aggradation or degradation; however, the spatial patterns of frozen rock point to permafrost aggradation following glacier surface lowering or retreat. This finding is significant for permafrost and cirque erosion studies in terms of frost-influence weathering in similar high-mountain settings. © 2020 Author(s).
英文关键词	bedrock; calcareous soil; electrical resistivity; glacier dynamics; ice margin; limestone; Little Ice Age; permafrost; Pleistocene; snow cover; thermal regime; weathering rate; Alps; Austria; Eastern Alps; Northern Calcareous Alps
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202190
作者单位	Working Group on Alpine Landscape Dynamics (ALADYN), Institute of Geography and Regional Science, University of Graz, Graz, Austria; Working Group on Geomorphology, Institute of Geography, University of Bayreuth, Bayreuth, Germany
推荐引用方式 GB/T 7714	Rode M.,Sass O.,Kellerer-Pirklbauer A.,et al. Permafrost distribution and conditions at the headwalls of two receding glaciers (Schladming and Hallstatt glaciers) in the Dachstein Massif, Northern Calcareous Alps, Austria[J],2020,14(4).
APA	Rode M.,Sass O.,Kellerer-Pirklbauer A.,Schnepfleitner H.,&Gitschthaler C..(2020).Permafrost distribution and conditions at the headwalls of two receding glaciers (Schladming and Hallstatt glaciers) in the Dachstein Massif, Northern Calcareous Alps, Austria.Cryosphere,14(4).
MLA	Rode M.,et al."Permafrost distribution and conditions at the headwalls of two receding glaciers (Schladming and Hallstatt glaciers) in the Dachstein Massif, Northern Calcareous Alps, Austria".Cryosphere 14.4(2020).