Fluid flow history from damage zone cements near the Dent and Rawthey faults, NW England

Woodcock, N. H. and Sayers, N. J. and Dickson, J. A. D. (2008) Fluid flow history from damage zone cements near the Dent and Rawthey faults, NW England. Journal of the Geological Society, 165 (4). pp. 829-837. DOI https://doi.org/10.1144/0016-76492007-133

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Abstract

Fault-related breccias, in Carboniferous limestone, have been well documented in the footwall damage zone to the reverse-oblique Dent Fault. This study describes breccias in the more complicated hanging wall, hosted in pre-deformed Ordovician and Silurian lithologies along the Dent Fault or one of its splays such as the Rawthey Fault. Brecciation style is shown to be influenced by lithology, with the most extensive brecciation in mechanically strong units: siliceous or calcareous mudstone, cemented sandstone and fine tuff. Most brecciation involves dilational strain in the fault damage zones. Attritional breccias are rare, even in fault cores. Dilation breccias are cemented sporadically by quartz or barite, but mostly by carbonate minerals. Transition matrix analysis shows that the sequence of hanging-wall carbonate cements matches that in the footwall: first dolomite or calcite, then ferroan dolomite, then ferroan calcite. This similarity suggests hydrological connectivity from hanging wall to footwall and through tens of cubic kilometres across the Dent–Rawthey fault system. Such connectivity is predicted across upper crustal faults that cut strong mechanical stratigraphy. It is proposed that fluid flow though the fault system was driven mainly by syntectonic topography above the hanging wall, and possibly also by thermal convection caused by a buried granite pluton in the footwall.

Item Type:	Article
Uncontrolled Keywords:	08AREP IA55 2008 P
Subjects:	02 - Geodynamics, Geophysics and Tectonics
Divisions:	02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title:	Journal of the Geological Society
Volume:	165
Page Range:	pp. 829-837
Identification Number:	https://doi.org/10.1144/0016-76492007-133
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/815

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