Conference proceeding
IODP Expedition 352 (Bonin Forearc); first results
American Geophysical Union Fall Meeting, Vol.2014
American Geophysical Union 2014 fall meeting
12/2014
Abstract
IODP Expedition #352 (Testing Subduction Initiation and Ophiolite Models by Drilling the Outer Izu-Bonin-Mariana Forearc: July 30-Sept. 29, 2014) is just underway at the time of writing. It is testing the Stern-Bloomer hypothesis that subduction initiation (SI) was followed by a strongly extensional period of slab sinking and trench roll-back and then by a transitional period leading to the establishment of significant slab-parallel plate motion and hence normal subduction. The Expedition aims to carry out offset drilling at two sites near 28 degrees 30'N in the Bonin forearc. Ideally, these together will give the vertical volcanic stratigraphy needed to trace the geodynamic and petrogenetic processes associated with SI, and provide the complete reference section required for comparison with volcanic sequences of possible SI origin found on land in ophiolite complexes and elsewhere. We predict, but need to confirm, a c. 1.0-1.5 km sequence with basal, MORB-like forearc basalts (known as FAB) marking the initial period of extension, boninites characterizing the transitional period, and tholeiitic and calc-alkaline lavas marking the establishment of normal arc volcanism. Study of such a sequence will enable us to understand the chemical gradients within and across these volcanic units, to reconstruct mantle flow and melting processes during the course of SI, and to test the hypothesis that fore-arc lithosphere created during SI is the birthplace of most supra-subduction zone ophiolites. Here, we present the first Expedition results, including (a) the volcanic stratigraphic record and subdivision into lava units, (b) the classifications and interpretations made possible by shipboard (portable XRF and ICP) analyses and down-hole measurements, and (c) the biostratigraphic, magnetic, mineralogical, sedimentary and structural constraints on the geological history of the SI section and the interactions between magmatic, hydrothermal and tectonic activity during its evolution.
Details
- Title: Subtitle
- IODP Expedition 352 (Bonin Forearc); first results
- Creators
- J. A Pearce - Cardiff UniversityMark K Reagan - University of Iowa USA United StatesR. J Stern - University of Texas Dallas USA United StatesK. E Petronotis - Integrated Ocean Drilling Program 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
- 9984240917402771
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