Correlating magnetic fabrics with finite strain : comparing results from mudrocks in the Variscan and Appalachian Orogens
Parés, J. M. (University of Michigan. Department of Geological Sciences)
Van Der Pluijm, B. A. (University of Michigan. Department of Geological Sciences)

Date:	2004
Abstract:	New magnetic anisotropy data from Variscan mudstones collected in the Cantabrian Arc, N Spain constrain the corresponding strain (shortening). The results are based on our previous study of mudrocks from the Valley and Ridge Province (Appalachians) where independent strain quantification of pencil structures permitted a correlation between magnetic fabric and tectonic strain. An exponential relationship between the AMS shape parameter T and tectonic shortening was found for the interval of 10-25% shortening: shortening (%)=17*exp(T), relationship that appears to be supported by tectonic strains up to 40%. The T parameter describes the shape of the magnetic susceptibility ellipsoid, which in pelitic rocks appears more sensitive to strain than the degree of anisotropy parameter P (or P'). In mudrocks from the Cantabrian Arc a positive correlation between T parameter and deformation intensity, reflected by cleavage domains spacing, is observed. Using the above relationship, we estimate the range of tectonic shortening for the Cantabrian mudstones. The correlation between strain and AMS offers a robust estimate of strain magnitude of 10-40% in weakly to moderately deformed clay-rich rocks, where other strain indicators are often lacking or are poorly preserved.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Anisotropy of Magnetic Susceptibility ; Finite strain ; Cantabrian Arc ; Valley and Ridge Province
Published in:	Geologica acta, Vol. 2, Núm. 3 (2004) , p. 213-220, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/82204
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000001428
DOI: 10.1344/105.000001428

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