Journal
JOURNAL OF STRUCTURAL GEOLOGY
Volume 58, Issue -, Pages 22-42Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jsg.2013.10.008
Keywords
Carbonate fault; Phyllosilicate; Fault zone heterogeneity; Seismic behaviour; Microstructure; Deformation mechanisms
Categories
Funding
- Natural Environment Research Council through a NERC PhD studentship [NE/J500215/1]
- NERC Standard Grant [NE/H021744/1]
- EPSRC [EP/K031414/1] Funding Source: UKRI
- NERC [NE/H021744/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/K031414/1] Funding Source: researchfish
- Natural Environment Research Council [1079527, NE/H021744/1] Funding Source: researchfish
Ask authors/readers for more resources
A significant proportion of moderate-large earthquakes, plus aftershocks, nucleate within and propagate through upper-crustal carbonate-dominated sequences, where the effects of lithological variations on fault behaviour are poorly understood. The Gubbio fault is an active (1984, Ms = 5.2) normal fault in Italy, hosted in Mesozoic Cenozoic limestones and interbedded marls. Fault core domains derived from limestone at the studied outcrop are characterised by fractures/hydrofractures and breccias and host a number of localised (<1.5 mm wide) principal slip zones (PSZs). The majority of displacement of up to 230 m is concentrated in these PSZs, which comprise cataclasites, gouges, and calcite veins. Degassing bubbles, 'quenched' calcite, and the transformation of smectite to illite, are also observed within PSZs, implying frictional heating and seismic slip. In contrast, marl-rich domains exhibit distributed shear planes bounding a continuous and pervasive foliation, defined by phyllosilicate-rich pressure-solution seams. Microstructures in the seams include folds/kinks of phyllosilicates and pressure shadows around clasts, consistent with aseismic fault creep. A model is proposed for the behaviour of lithologically complex carbonate-hosted faults during the seismic cycle, whereby limestone-dominated fault core domains behave in a predominantly seismic manner, whereas phyllosilicate-rich domains behave in a predominantly aseismic manner. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available