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Critical taper analysis reveals lithological control of variations in detachment strength: An analysis of the Alpine basal detachment (Swiss Alps)

von Hagke, C. and Oncken, O. and Evseev, S. (2014) Critical taper analysis reveals lithological control of variations in detachment strength: An analysis of the Alpine basal detachment (Swiss Alps). Geochemistry, Geophysics, Geosystems, 15 (1). pp. 176-191. ISSN 1525-2027. https://resolver.caltech.edu/CaltechAUTHORS:20140410-090813283

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Abstract

Although evidence for weak detachments underlying foreland thrust belts exists, very little is known about the lateral variations in effective strength, as well as the geological nature of such variations. Using critical taper analysis, we show that a detailed and systematic measurement of surface slope of the Central European Alps reveals variations in strength parameter F along the detachment, based on the argument that the Alps are close to the critical state. We show that the basal detachment is very weak near the deformation front but strengthens toward the hinterland. Very low F (effective coefficient of friction plus normalized cohesion) values of <0.1 and even 0.05 occur within evaporites and within shales in Triassic (west) or Upper Cretaceous/Lower Tertiary sequences (east) used by the Alpine sole detachment. These very low values in shales—comparably low values are reported from other orogens—are caused partly by slightly elevated pore pressures (λ > 0.54) but may also require additional mechanisms of dynamic weakening.


Item Type:Article
Related URLs:
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http://dx.doi.org/10.1002/2013GC005018DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2013GC005018/abstractPublisherArticle
Additional Information:© 2013 American Geophysical Union. Received 29 August 2013; Revised 12 November 2013; Accepted 24 November 2013; Published 31 January 2014. Nadaya Cubas and Olaf Zielke helped with Matlab coding. This manuscript benefited from discussions with Oliver Heidbach, Friedhelm von Blanckenburg, Tibi Codilean, Mark Handy, Kamil Ustaszewski, and Fang-Lin Wang. This research was conducted in the framework of the ESF TopoEurope CRP "Thermo-Europe." The German Research Foundation (DFG) provided funding by research grant number CE 175/1-1. John Suppe, Jon Mosar, Jean-Pierre Burg, and one anonymous reviewer are thanked for constructive reviews; Joel Baker and Janne Blichert-Toft are thanked for editorial handling.
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Funding AgencyGrant Number
German Research Foundation (DFG) CE 175/1-1
Subject Keywords:critical taper; central Alps; detachment strength; wedge
Issue or Number:1
Record Number:CaltechAUTHORS:20140410-090813283
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140410-090813283
Official Citation:von Hagke, C., O. Oncken, and S. Evseev (2014), Critical taper analysis reveals lithological control of variations in detachment strength: An analysis of the Alpine basal detachment (Swiss Alps), Geochem. Geophys. Geosyst., 15, 176–191, doi:10.1002/2013GC005018.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44844
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:10 Apr 2014 18:07
Last Modified:03 Oct 2019 06:23

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