Effective crustal permeability controls fault evolution : an integrated structural, mineralogical and isotopic study in granitic gneiss, Monte Rosa, northern Italy
Lawther, Susan E.M. and Dempster, Tim J. and Shipton, Zoe K. and Boyce, Adrian J. (2016) Effective crustal permeability controls fault evolution : an integrated structural, mineralogical and isotopic study in granitic gneiss, Monte Rosa, northern Italy. Tectonophysics, 690 (Part A). pp. 160-173. ISSN 0040-1951 (https://doi.org/10.1016/j.tecto.2016.07.010)
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Abstract
Two dextral faults within granitic gneiss in the Monte Rosa nappe, northern Italy reveal key differences in their evolution controlled by evolving permeability and water/rock reactions. The comparison reveals that identical host rock lithologies develop radically different mineralogies within the fault zones, resulting in fundamentally different deformation histories. Oxygen and hydrogen isotope analyses coupled to microstructural characterisation show that infiltration of meteoric water occurred into both fault zones. The smaller Virgin Fault shows evidence of periodic closed system behaviour, which promoted the growth of hydrothermal K-feldspar, whilst the more open system behaviour of the adjacent Ciao Ciao Fault generated a weaker muscovite-rich fault core, which promoted a step change in fault evolution. Effective crustal permeability is a vital control on fault evolution and, coupled to the temperature (i.e. depth) at which key mineral transformations occur, is probably a more significant factor than host rock strength in controlling fault development. The study suggests that whether a fault in granitic basement grows into a large structure may be largely controlled by the initial hydrological properties of the host rocks. Small faults exposed at the surface may therefore be evolutionary “dead-ends” that typically do not represent the early stages in the development of larger faults.
ORCID iDs
Lawther, Susan E.M., Dempster, Tim J., Shipton, Zoe K. ORCID: https://orcid.org/0000-0002-2268-7750 and Boyce, Adrian J.;-
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Item type: Article ID code: 57298 Dates: DateEvent28 October 2016Published18 July 2016Published Online15 July 2016AcceptedSubjects: Technology > Engineering (General). Civil engineering (General)
Science > GeologyDepartment: Faculty of Engineering > Civil and Environmental Engineering Depositing user: Pure Administrator Date deposited: 05 Aug 2016 12:02 Last modified: 22 Sep 2024 00:50 URI: https://strathprints.strath.ac.uk/id/eprint/57298