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From basalts to boninites: The geodynamics of volcanic expression during induced subduction initiation

Leng, Wei and Gurnis, Michael and Asimow, Paul D. (2012) From basalts to boninites: The geodynamics of volcanic expression during induced subduction initiation. Lithosphere, 4 (6). pp. 511-523. ISSN 1941-8264. doi:10.1130/L215.1.

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Subduction initiation may unfold via different pathways in response to plate strength, plate age, and driving mechanism. Such pathways influence volcanism on the overriding plate and may be preserved in the sequence of erupted volcanic products. Here, we parameterize melting in a mechanical model to determine the volcanic products that form in response to different subduction initiation modes. We find that with a mode of continuous initiation with infant-arc spreading, the foundering of the subducting slab and water release from the slab govern a succession from basalts with compositions similar to mid-ocean-ridge basalts (MORB) to boninites. The modeled transition from MORB-like to boninite composition typically occurs within a few million years. When plate strength is reduced, the subducting slab tends to segment, with extensive melting occurring when the slab breaks; most melting occurs close to the trench. When plate strength increases, subduction initiation becomes continuous without infant-arc spreading; such a mode leads to a limited, very low degree of melting occurring during a long interval of plate convergence before subduction initiation starts, although extensive melting near the trench is still possible when subduction initiation starts after a protracted period of plate convergence (∼10 m.y.). If the subduction initiation is driven by constant stresses, such as through ridge push, the slab subducts rapidly in response to continuous acceleration of the plate under action of the far-field push; significant melting, including boninite eruption, can be generated within a few million years with no trench migration. Based on the tectonic and volcanic evolution, these different modes may be applicable to the initiation of the Izu-Bonin-Mariana arc (infant-arc spreading and a sequence from MORB-like to boninites), the New Hebrides arc (slab segments in the upper mantle), the Puysegur Trench in New Zealand (scarce distribution of volcanism and no infant-arc spreading), and the Aleutian Trench (strong volcanism and no infant-arc spreading).

Item Type:Article
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URLURL TypeDescription
Gurnis, Michael0000-0003-1704-597X
Asimow, Paul D.0000-0001-6025-8925
Additional Information:© 2012 Geological Society of America. Manuscript Received 29 March 2012; Revised Manuscript Received 20 August 2012; Manuscript Accepted 28 September 2012. Published online 26 October 2012. We thank Bob Stern and two anonymous reviewers, whose comments help to improve the manuscript. Leng was supported by the O.K. Earl Fellowship at Caltech. Additional support was provided by the National Science Foundation (EAR-0810303) and the Caltech Tectonics Observatory (by the Gordon and Betty Moore Foundation) with contribution number TO 209.
Group:Caltech Tectonics Observatory, Seismological Laboratory
Funding AgencyGrant Number
Caltech O. K. Earl FellowshipUNSPECIFIED
Caltech Tectonics ObservatoryUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Tectonics Observatory209
Issue or Number:6
Record Number:CaltechAUTHORS:20130103-085750674
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36136
Deposited By: Tony Diaz
Deposited On:10 Jan 2013 19:21
Last Modified:09 Nov 2021 23:20

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