Conference proceeding
The ophiolite - oceanic fore-arc connection
American Geophysical Union Fall Meeting, Vol.2014
American Geophysical Union 2014 fall meeting
12/2014
Abstract
Miyashiro (1973, EPSL) put forward the hypothesis that many ophiolites are generated in subduction zone settings. More recently, ophiolitic sequences including MORB-like basalts underlying boninites or other subduction-related rock types have been linked to near-trench spreading during subduction infancy (e.g., Stern and Bloomer, 1992, GSA Bull.; Shervais, 2001, G-cubed; Stern et al., 2012, Lithos.). These contentions were given strong support by the results of Shinkai 6500 diving in the Izu-Bonin-Mariana (IBM) fore-arc (e.g., Reagan et al., 2010, G-cubed; Ishizuka et al., 2011, EPSL; Reagan et al., 2013, EPSL). Based on widely spaced dives and grab sampling at disbursed dive stops, these studies concluded that the most abundant and most submerged volcanic rocks in the IBM fore-arc are MORB-like basalts (fore-arc basalts or FAB), and that these basalts appear to be part of a crustal sequence of gabbro, dolerite, FAB, boninite, and normal arc lavas overlying depleted peridotite. This ophiolitic sequence was further postulated to make up most or all of the IBM fore-arc from Guam to Japan, with similar magmatic ages (52 Ma FAB to 45 Ma arc) north to south, reflecting a western-Pacific wide subduction initiation event. At the time of this writing, IODP Expedition 352 is about to set sail, with a principal goal of drilling the entire volcanic sequence in the Bonin fore-arc. This drilling will define the compositional gradients through the volcanic sequence associated with subduction initiation and arc infancy, and test the hypothesized oceanic fore-arc - ophiolite genetic relationship. A primary goal of this expedition is to illustrate how mantle compositions and melting processes evolved during decompression melting of asthenosphere during subduction initiation to later flux melting of depleted mantle. These insights will provide important empirical constraints for geodynamic models of subduction initiation and early arc development.
Details
- Title: Subtitle
- The ophiolite - oceanic fore-arc connection
- Creators
- M. K Reagan - University of Iowa Iowa City, IA USA United StatesJ. A Pearce - Cardiff UniversityR. J Stern - University of Texas Dallas Richardson, TX USA United StatesO Ishizuka - Geological Survey of JapanK. E Petronotis - Integrated Ocean Drilling Program College Station, TX USA United States
- Resource Type
- Conference proceeding
- Publication Details
- American Geophysical Union Fall Meeting, Vol.2014
- Conference
- American Geophysical Union 2014 fall meeting
- Publisher
- American Geophysical Union
- Alternative title
- AGU 2014 fall meeting
- Language
- English
- Date published
- 12/2014
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240912202771
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