Testing Subduction Initiation and Ophiolite Models by Drilling the Bonin Forearc
Proposal #696-Full4 >> go to the full version (PDF)
Scientific Prospectus >> To be uploaded
Pre-cruise Training Report >> Click HERE
30 Jul. to 29 Sep. 2014
Yokohama (Japan) to Keelung (Taiwan)
This expedition, based on IODP Proposal 696-Full4, aims to examine early processes in magmatic evolution, chemostratigraphy and arc crustal accretion that are associated with subduction initiation at intra-oceanic convergence plate margins. The objectives will be achieved by coring through the sediment and into the volcanic stratigraphy at two sites on the outer Izu-Bonin-Mariana (IBM) forearc trench system, with total penetrations of ~ 1 km in oceanic crust in water depths between 3.1 and 4.8 km.
Scientific objectives are to (1) obtain a high-fidelity record of magmatic evolution during subduction initiation by coring volcanic rocks down to underlying intrusive rocks, including obtaining radiometric and biostratigraphic ages; (2) understand the chemical gradients within the rock units and across their transitions, as well as their tectonic significance; and (3) provide empirical constraints for subduction initiation geodynamic models by examining how mantle melting processes evolve from early decompression melting of fertile asthenosphere to late flux melting of depleted mantle. Results from these objectives will help to test the hypotheses that (1) “forearc basalt” tholeiites lie beneath boninites; and (2) forearc lithosphere created during subduction initiation is the birthplace of suprasubduction zone ophiolites.
Julian Pearce & Mark Reagan
Japan-based Scientists applied through J-DESC
|Name||Affiliation||Title||Role on board|
|Kenji Shimizu||JAMSTEC/IFREE||Research Scientist||Core Description-Petrologist|
|Katsuyoshi Michibayashi||Shizuoka Univ.||Professor||Physical Properties Specialist|
|Tetsuya Sakuyama||JAMSTEC/IFREE||Scientist||Physical Properties Specialist|
|Marie Python||Hokkaido Univ.||Assistant Professor||Core Description-Petrologist/Alteration|
Japan-based scientists may apply to J-DESC.
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