Effect of Variations in Magma Supply on the Crustal Structure of Mid-Ocean Ridges: Insights from the Western Galápagos Spreading Center

Date
2014-08
Authors
Canales, Juan Pablo
Dunn, Robert A.
Ito, Garrett
Detrick, Robert S.
Sallarès, Valentí
Contributor
Advisor
Department
Instructor
Depositor
Speaker
Researcher
Consultant
Interviewer
Journal Title
Journal ISSN
Volume Title
Publisher
John Wiley & Sons, Inc.
Volume
Number/Issue
Starting Page
Ending Page
Alternative Title
Abstract
We report results from a seismic refraction experiment across three sections of the Western Galápagos Spreading Center (WGSC) with contrasting axial morphology. Tomography models show the presence of an axial low velocity zone at the three study areas. After correcting for thermal effects, we estimate the melt content within these regions. At each of the three sites, the largest melt reservoir is located at or just below the Moho, which is 5.25 km deep at site GALA-1 within an axial-valley morphological domain, 6 km deep at GALA-2 in a morphological transitional domain, and 7.5 km deep at GALA-3 within the axial-high domain. The tomography model does not require melt above the Moho at GALA-1, nor at GALA-2, where we find little evidence for crustal melt between the Moho and a melt lens previously imaged at 2.8 km depth. In contrast, at GALA-3 the low velocity anomaly requires the presence of a few percent melt throughout the crust, with two distinct crustal reservoirs: one at the level of the seismically imaged melt lens reflector (1.6 km deep), and a deeper one at 3–4 km depth. The differences in axial melt content and distribution between the three sites are consequences of variations in magma supply, with lower magma supply resulting in less frequent upward migration of melt from the main Moho reservoir to crustal levels. At higher melt supply, transfer of melt to the crust above the main Moho reservoir becomes more frequent, resulting in the formation of distinct crustal melt reservoirs.
Description
Keywords
axial crust, magma supply, mid-ocean ridges (MORs), Western Galápagos Spreading Center (WGSC)
Citation
Canales, J. P., Dunn, R. A., Ito, G., Detrick, R. S. and Sallarès, V. (2014) Effect of Variations in Magma Supply on the Crustal Structure of Mid-Ocean Ridges, in The Galápagos: A Natural Laboratory for the Earth Sciences (eds K. S. Harpp, E. Mittelstaedt, N. d'Ozouville and D. W. Graham), John Wiley & Sons, Inc, Hoboken, New Jersey.
Extent
30
Format
Geographic Location
Time Period
Related To
Rights
Copyright © 2014 American Geophysical Union.
Rights Holder
Email libraryada-l@lists.hawaii.edu if you need this content in ADA-compliant format.