Open fissures along faults: Variscan examples from Gower, South Wales

Wright, V. and Woodcock, N. H. and Dickson, J. A. D. (2009) Open fissures along faults: Variscan examples from Gower, South Wales. Geological Magazine, 146 (6). pp. 890-902. DOI 10.1017/S001675680999001X

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Abstract

The extent to which persistent, rather than transient, fissures (wide planar voids) can exist along upper crustal faults is important in assessing fault permeability to mineral and hydrocarbon-bearing fluids. Variscan (late Carboniferous) faults cutting Dinantian (Lower Carboniferous) limestones on the Gower peninsula, South Wales, host clear evidence for fissures up to several metres wide. Evidence includes dendritic hematite growth and elongate calcite growth into open voids, spar ball and cockade breccia formation, laminated sediment infill and void-collapse breccias. Detailed mapping reveals cross-cutting geometries and brecciation of earlier fissure fills, showing that fissures were formed during, rather than after, active faulting. Fissures therefore probably formed by geometric mismatch between displaced fault walls, rather than by solution widening along inactive faults.

Item Type: Article
Uncontrolled Keywords: 09AREP; IA58, Part III
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Geological Magazine
Volume: 146
Page Range: pp. 890-902
Identification Number: 10.1017/S001675680999001X
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:04
Last Modified: 23 Jul 2013 09:54
URI: http://eprints.esc.cam.ac.uk/id/eprint/818

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