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Sedimentary and volcanic record of the nascent Izu-Bonin-Mariana arc from IODP Site U1438

Waldman, Ryan J. and Marsaglia, Kathleen M. and Hickey-Vargas, Rosemary and Ishizuka, Osamu and Johnson, Kyle E. and McCarthy, Anders and Yogodzinski, Gene and Samajpati, Eshita and Li, He and Laxton, Kate and Savov, Ivan P. and Meffre, Sebastién and Arculus, Richard J. and Bandini, Alexandre N. and Barth, Andrew P. and Bogus, Kara and Brandl, Philipp A. and Gurnis, Michael and Jiang, Fuqing (2021) Sedimentary and volcanic record of the nascent Izu-Bonin-Mariana arc from IODP Site U1438. Geological Society of America Bulletin, 133 (7-8). pp. 1421-1440. ISSN 0016-7606. doi:10.1130/B35612.1.

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The oldest known, intact sedimentary record of a nascent intraoceanic arc was recovered in a ∼100-m-thick unit (IV) above ca. 49 Ma basaltic basement at International Ocean Discovery Program Site U1438 in the Amami Sankaku Basin. During deposition of Unit IV the site was located ∼250 km from the plate edge, where Izu-Bonin-Mariana subduction initiated at 52 Ma. Basement basalts are overlain by a mudstone-dominated subunit (IVC) with a thin basal layer of dark brown metalliferous mudstone followed by mudstone with sparse, graded laminae of amphibole- and biotite-bearing tuffaceous sandstone and siltstone. Amphibole and zircon ages from these laminae suggest that the intermediate subduction-related magmatism that sourced them initiated at ca. 47 Ma soon after basement formation. Overlying volcaniclastic, sandy, gravity-flow deposits (subunit IVB) have a different provenance; shallow water fauna and tachylitic glass fragments indicate a source volcanic edifice that rose above the carbonate compensation depth and may have been emergent. Basaltic andesite intervals in upper subunit IVB have textures suggesting emplacement as intrusions into unconsolidated sediment on a volcanic center with geochemical and petrological characteristics of mafic, differentiated island arc magmatism. Distinctive Hf-Nd isotope characteristics similar to the least-radiogenic Izu-Bonin-Mariana boninites support a relatively old age for the basaltic andesites similar to detrital amphibole dated at 47 Ma. The absence of boninites at that time may have resulted from the position of Site U1438 at a greater distance from the plate edge. The upper interval of mudstone with tuffaceous beds (subunit IVA) progresses upsection into Unit III, part of a wedge of sediment fed by growing arc-axis volcanoes to the east. At Site U1438, in what was to become a reararc position, the succession of early extensional basaltic magmatism associated with spontaneous subduction initiation is followed by a rapid transition into potentially widespread subduction-related magmatism and sedimentation prior to the onset of focused magmatism and major arc building.

Item Type:Article
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Bogus, Kara0000-0003-4690-0576
Gurnis, Michael0000-0003-1704-597X
Additional Information:© 2020 Geological Society of America. Manuscript Received 2 January 2020; Revised Manuscript Received 17 August 2020; Manuscript Accepted 14 September 2020. We thank the International Ocean Discovery Program (IODP) for access to core samples and acknowledge the IODP Expedition 351 shipboard scientists, technicians, and captain and crew of the R/V JOIDES Resolution, who made this study possible. Awards to K. Marsaglia from the National Science Foundation (OCE-1503694) and Ocean Leadership and from the Geological Society of America to K. Johnson supported this work. O. Ishizuka appreciates Japan Agency for Marine-Earth Science and Technology and Japan Drilling Earth Science Consortium for their funding to join the expedition and post cruise research. O. Ishizuka used Grant-in-Aid (B) (No. 25287133) for shore-based research. H. Li appreciates support from National Natural Science Foundation of China (91958110 and 41473029) and use of facilities at Australian National University. A. McCarthy acknowledges the support of Swiss National Science Foundation Grant P2LAP2_171819. We thank K. Tani for providing the opportunity to use SELFRAG at National Museum of Nature and Science and E. Curtis for providing access to olivine data. We also appreciate Oregon State University research reactor for providing irradiation opportunities. R. Hickey-Vargas, E. Samajpati, and G. Yogodzinski are grateful for support received from NSF (OCE 1537861 and 1537135) and for the use of facilities at the Florida Center for Analytical Electron Microscopy at Florida International University and the Center for Elemental Mass Spectrometry at the University of South Carolina. Constructive reviews by J. Gill, A. Robertson, and Associate Editor N. Riggs greatly improved the manuscript.
Group:Seismological Laboratory
Funding AgencyGrant Number
Geological Society of AmericaUNSPECIFIED
Japan Agency for Marine-Earth Science and TechnologyUNSPECIFIED
Japan Drilling Earth Science ConsortiumUNSPECIFIED
Japan Society for the Promotion of Science (JSPS)25287133
National Natural Science Foundation of China91958110
National Natural Science Foundation of China41473029
Swiss National Science Foundation (SNSF)P2LAP2_171819
Issue or Number:7-8
Record Number:CaltechAUTHORS:20201124-095124275
Persistent URL:
Official Citation:Ryan J. Waldman, Kathleen M. Marsaglia, Rosemary Hickey-Vargas, Osamu Ishizuka, Kyle E. Johnson, Anders McCarthy, Gene Yogodzinski, Eshita Samajpati, He Li, Kate Laxton, Ivan P. Savov, Sebastien Meffre, Richard J. Arculus, Alexandre N. Bandini, Andrew P. Barth, Kara Bogus, Philipp A. Brandl, Michael Gurnis, Fuqing Jiang; Sedimentary and volcanic record of the nascent Izu-Bonin-Mariana arc from IODP Site U1438. GSA Bulletin 2020; 133 (7-8): 1421–1440. doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106805
Deposited By: Tony Diaz
Deposited On:24 Nov 2020 18:05
Last Modified:08 Jul 2021 20:37

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