Die hochwürmzeitlichen Rückzugsphasen des Rhein-Vorlandgletschers und der erste alpine Eisrandkomplex im Spätglazial

Keller, Oskar; Krayss, Edgar

doi:10.5194/gh-42-169-1987

Cited by 19 publications

(10 citation statements)

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“…Evidence for one or even two glacial advances during the early part of this glaciation has been discussed on several occasions (Schlüchter et al 1987;Keller & Krayss 1998;Preusser et al 2003;Preusser 2004;Ivy-Ochs et al 2008). According to present dating evidence, these glacial advances occurred during MIS 5d and/or MIS 4, and represent independent phases of ice build-up and decay (cf.…”

Section: Middle-late Pleistocene Of Central Northern Switzerlandmentioning

confidence: 77%

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Quaternary glaciation history of northern Switzerland

Preusser¹

2012

Quaternary International

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Abstract:A revised glaciation history of the northern foreland of the Swiss Alps is presented by summarising field evidence and chronological data for different key sites and regions. The oldest Quaternary sediments of Switzerland are multiphase gravels intercalated by till and overbank deposits ('Deckenschotter'). Important differences in the base level within the gravel deposits allows the distinguishing of two complex units ('Höhere Deckenschotter', 'Tiefere Deckenschotter'), separated by a period of substantial incision. Mammal remains place the older unit ('Höhere Deckenschotter') into zone MN 17 (2.6-1.

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Section: Middle-late Pleistocene Of Central Northern Switzerlandmentioning

confidence: 77%

“…Ivy-Ochs et al 2008). Following Keller & Krayss (1998), the MIS 4 advance reached Untersee and was only some 10 km less extensive than the Last Glaciation of the Swiss lowlands.…”

Section: Middle-late Pleistocene Of Central Northern Switzerlandmentioning

confidence: 99%

Quaternary glaciation history of northern Switzerland

Preusser¹

2012

Quaternary International

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“…The reconstruction of Benz-Meier (2003) is based on the earlier works of Jäckli (1962Jäckli ( , 1970 and also of Keller and Krayss (1987, 1989, 1993, 1994. We refer to it as BenzMeier (2003) despite its earlier origin.…”

Section: The Rhine Glacier Modelmentioning

confidence: 99%

“…In the accumulation area, trimlines represent the upper limit of glacial erosion and define the minimum elevation of the ice surface (Florineth and Schlüchter, 1998;Kelly et al, 2004). This large amount of geomorphic information for the Rhine glacier, probably the best documented of any paleo-glacier, has been used to create detailed maps of reconstructed ice extent and ice surface elevation at the LGM (e.g., Jäckli, 1962Jäckli, , 1970Keller and Krayss, 1987, 1989, 1993, 1994Benz-Meier, 2003;Kelly et al, 2004;Bini et al, 2009).…”

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confidence: 99%

Numerical reconstructions of the flow and basal conditions of the Rhine glacier, European Central Alps, at the Last Glacial Maximum

et al. 2018

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Abstract. At the Last Glacial Maximum (LGM), the Rhine glacier in the Swiss Alps covered an area of about 16 000 km 2 . As part of an integrative study about the safety of repositories for radioactive waste under ice age conditions in Switzerland, we modeled the Rhine glacier using a thermodynamically coupled three-dimensional, transient Stokes flow and heat transport model down to a horizontal resolution of about 500 m. The accumulation and ablation gradients that roughly reproduced the geomorphic reconstructions of glacial extent and ice thickness suggested extremely cold (T July ∼ 0 • C at the glacier terminus) and dry (∼ 10 % to 20 % of today's precipitation) climatic conditions. Forcing the numerical simulations with warmer and wetter conditions that better matched LGM climate proxy records yielded a glacier on average 500 to 700 m thicker than geomorphic reconstructions. Mass balance gradients also controlled ice velocities, fluxes, and sliding speeds. These gradients, however, had only a small effect on basal conditions. All simulations indicated that basal ice reached the pressure melting point over much of the Rhine and Linth piedmont lobes, and also in the glacial valleys that fed these lobes. Only the outer margin of the lobes, bedrock highs beneath the lobes, and Alpine valleys at high elevations in the accumulation zone remained cold based. The Rhine glacier was thus polythermal. Sliding speed estimated with a linear sliding rule ranged from 20 to 100 m a −1 in the lobes and 50 to 250 m a −1 in Alpine valleys. Velocity ratios (sliding to surface speeds) were > 80 % in lobes and ∼ 60 % in valleys. Basal shear stress was very low in the lobes (0.03-0.1 MPa) and much higher in Alpine valleys (> 0.2 MPa). In these valleys, viscous strain heating was a dominant source of heat, particularly when shear rates in the ice increased due to flow constrictions, confluences, or flow past large bedrock obstacles, contributing locally up to several watts per square meter but on average 0.03 to 0.2 W m −2 . Basal friction acted as a heat source at the bed of about 0.02 W m −2 , 4 to 6 times less than the geothermal heat flow which is locally high (up to 0.12 W m −2 ). In the lobes, despite low surface slopes and low basal shear stresses, sliding dictated main fluxes of ice, which closely followed bedrock topography: ice was channeled in between bedrock highs along troughs, some of which coincided with glacially eroded overdeepenings. These sliding conditions may have favored glacial erosion by abrasion and quarrying. Our results confirmed general earlier findings but provided more insights into the detailed flow and basal conditions of the Rhine glacier at the LGM. Our model results suggested that the trimline could have been buried by a significant thickness of cold ice. These findings have significant implications for interpreting trimlines in the Alps and for our understanding of ice-climate interactions.

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“…For the 5 ice surface, we use either the digitally available reconstructed glacier surface of Benz-Meier (2003) or an ice surface obtained from a previous numerical simulation. The reconstruction of Benz-Meier (2003) is based on the earlier works of Jäckli (Jäckli, 1962;Jäckli, 1970) and also of Keller and Krayss (Keller and Krayss, 1987, 1989, 1993, 1994. We refer to it as Benz-Meier (2003) despite its earlier origin.…”

mentioning

confidence: 99%

Numerical reconstructions of the flow and basal conditions of the Rhine glacier, European Central Alps, at the Last Glacial Maximum

Cohen¹,

Gillet-Chaulet²,

Haeberli³

et al. 2017

Preprint

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Abstract. At the Last Glacial Maximum (LGM), the Rhine glacier in the Swiss Alps covered an area of about 16,000 km 2 .As part of an integrative study about the safety of repositories for radioactive waste under ice age conditions in Switzerland, we modeled the Rhine glacier using a fully-coupled, three-dimensional, transient, thermo-mechanical Stokes flow model down to a horizontal resolution of about 500 m. The accumulation and ablation gradients that roughly reproduced the geomorphic reconstructions of glacial extent and ice thickness suggested extremely cold (T July ∼ 0 • C at the glacier terminus) and dry (∼ 10 5 to 20% of today's precipitation) climatic conditions. Forcing the numerical simulations with warmer and wetter conditions that better matched LGM climate proxy records yielded a glacier on average 500 to 700 m thicker than geomorphic reconstructions.Mass balance gradients also controlled ice velocities, fluxes, and sliding speeds. These gradients, however, had only a small effect on basal conditions. All simulations indicated that basal ice reached the pressure melting point over much of the Rhine and Linth piedmont lobes, and also in the glacial valleys that fed these lobes. Only the outer margin of the lobes, bedrock highs ). In the lobes, despite low surface slopes and low basal shear stresses, sliding dictated main fluxes of ice which closely followed bedrock topography: ice was channeled in between bedrock highs along troughs, some of which coincided with glacially eroded overdeepenings. These sliding conditions may have favored glacial erosion by abrasion and quarrying. 20Our results confirmed general earlier findings but provided more insights into the detailed flow and basal conditions of the Rhine glacier at the LGM. Our model results suggested that the trimline could have been buried by a significant thickness of cold ice. These findings have significant implications for interpreting trimlines in the Alps and for our understanding of ice-climate interactions.

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Die hochwürmzeitlichen Rückzugsphasen des Rhein-Vorlandgletschers und der erste alpine Eisrandkomplex im Spätglazial

Cited by 19 publications

References 0 publications

Quaternary glaciation history of northern Switzerland

Quaternary glaciation history of northern Switzerland

Numerical reconstructions of the flow and basal conditions of the Rhine glacier, European Central Alps, at the Last Glacial Maximum

Numerical reconstructions of the flow and basal conditions of the Rhine glacier, European Central Alps, at the Last Glacial Maximum

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