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Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system

J. Pablo Canales, Robert A. Dunn, Ryuta Arai and Robert A. Sohn
Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system
Geology (Boulder) (May 2017) 45 (5): 451-454


Hydrothermal circulation at mid-ocean ridge volcanic segments extracts heat from crustal magma bodies. However, the heat source driving hydrothermal circulation in ultramafic outcrops, where mantle rocks are exhumed in low-magma-supply environments, has remained enigmatic. Here we use a three-dimensional P-wave velocity model derived from active-source wide-angle refraction-reflection ocean bottom seismometer data and pre-stack depth-migrated images derived from multichannel seismic reflection data to investigate the internal structure of the Rainbow ultramafic massif, which is located in a non-transform discontinuity of the Mid-Atlantic Ridge. Seismic imaging reveals that the ultramafic rocks composing the Rainbow massif have been intruded by a large number of magmatic sills, distributed throughout the massif at depths of approximately 2-10 km. These sills, which appear to be at varying stages of crystallization, can supply the heat needed to drive high-temperature hydrothermal circulation, and thus provide an explanation for the hydrothermal discharge observed in this ultramafic setting. Our results demonstrate that high-temperature hydrothermal systems can be driven by heat from deep-sourced magma even in exhumed ultramafic lithosphere with very low magma supply.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 45
Serial Issue: 5
Title: Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system
Affiliation: Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA, United States
Pages: 451-454
Published: 201705
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 30
Accession Number: 2017-041892
Categories: Solid-earth geophysicsIgneous and metamorphic petrologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2017134
Illustration Description: illus. incl. sects., sketch map
N35°00'00" - N36°30'00", W34°19'60" - W33°30'00"
Secondary Affiliation: University of Hawaii at Manoa, USA, United StatesJapan Agency for Marine-Earth Science and Technology, JPN, Japan
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201723
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