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Earthquake rupturing as a mineralizing agent in hydrothermal systems

Richard H. Sibson
Earthquake rupturing as a mineralizing agent in hydrothermal systems
Geology (Boulder) (August 1987) 15 (8): 701-704


Much fault-hosted epithermal mineralization is localized in dilational jogs between en echelon fault segments, as fissure veins or as hydrothermally cemented, high-dilation wall-rock breccias. Jog widths may range from millimetres to kilometres; vein textures record histories of incremental development. Perturbation or arrest of earthquake ruptures at dilational jogs has been observed and is believed to involve extensional fracturing at the rupture tip, locally reducing fluid pressure and inducing suctions opposing rapid slip transfer across the jog. This forced fissuring leads to brecciation by hydraulic implosion and to a concentrated fluid influx, allowing delayed slip transfer accompanied by aftershock activity. Within the southern San Andreas fault system, major dilational jogs extend throughout the seismogenic regime and form loci for magmatic-hydrothermal systems; they act as vertical pipelike conduits for enhanced fluid flow. Rupture termination at these structures has sometimes been followed by hydrothermal eruptions, suggesting that high-level boiling events are triggered by the arrest mechanism. It thus seems probable that episodic mineral deposition in the top 1-2 km of such jogs is induced by the dynamic effects of rupturing on the flanking strike-slip faults.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 15
Serial Issue: 8
Title: Earthquake rupturing as a mineralizing agent in hydrothermal systems
Author(s): Sibson, Richard H.
Affiliation: Univ. Calif., Dep. Geol. Sci., Santa Barbara, CA, United States
Pages: 701-704
Published: 198708
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 31
Accession Number: 1987-070672
Categories: Economic geology, geology of ore depositsStructural geologySeismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch maps
N32°34'60" - N33°25'00", W116°10'00" - W114°25'00"
S47°30'00" - S34°30'00", E166°30'00" - E178°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data supplied by Institute of Geological and Nuclear Sciences Limited (GNS Science), Lower Hutt, New Zealand
Update Code: 1987
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