Large volume submarine ignimbrites in the Shikoku Basin; an example for explosive volcanism in the Western Pacific during the late Miocene

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doi: 10.1002/2014GC005263
Author(s): Kutterolf, Steffen; Schindlbeck, Julie C.; Scudder, Rachel P.; Murray, Richard W.; Pickering, Kevin T.; Freundt, Armin; Labanieh, Shasa; Heydolph, Ken; Saito, Sanny; Naruse, Hajime; Underwood, Michael B.; Wu, Huaichun
Author Affiliation(s): Primary:
Leibniz Institute for Marine Sciences, Helmholtz Center for Ocean Research, Kiel, Germany
Boston University, United States
University College London, United Kingdom
Institut Français de Recherche pour l'Exploitation de la Mer, France
Japan Agency for Marine-Earth Science and Technology, Japan
University of Kyoto, Japan
University of Missouri-Columbia, United States
China University of Geosciences, China
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 15(5), p.1837-1851. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 61 refs.; illus., incl. sketch map
Summary: During IODP Expedition 322, an interval of Late Miocene (7.6 to ∼9.1 Ma) tuffaceous and volcaniclastic sandstones was discovered in the Shikoku Basin (Site C0011B), Nankai region. This interval consists of bioturbated silty claystone including four 1-7 m thick interbeds of tuffaceous sandstones (TST) containing 57-82% (by volume) pyroclasts. We use major and trace element glass compositions, as well as radiogenic isotope compositions, to show that the tuffaceous sandstones beds derived from single eruptive events, and that the majority (TST 1, 2, 3a) came from different eruptions from a similar source region, which we have identified to be the Japanese mainland, 350 km away. In particular, diagnostic trace element ratios (e.g., Th/La, Sm/La, Rb/Hf, Th/Nb, and U/Th) and isotopic data indicate a marked contribution from a mantle source beneath continental crust, which is most consistent with a Japanese mainland source and likely excludes the Izu-Bonin island arc and back arc as a source region for the younger TST beds. Nevertheless, some of the chemical data measured on the oldest sandstone bed (TST 3b, Unit IIb) show affinity to or can clearly be attributed to an Izu-Bonin composition. While we cannot completely exclude the possibility that all TST beds derived from unknown and exotic Izu-Bonin source(s), the collected lines of evidence are most consistent with an origin from the paleo-Honshu arc for TST 1 through 3a. We therefore suggest the former collision zone between the Izu-Bonin arc and Honshu paleo-arc as the most likely region where the eruptive products entered the ocean, also concurrent with nearby (∼200 km) possible Miocene source areas for the tuffaceous sandstones at the paleo-NE-Honshu arc. Estimating the distribution area of the tuffaceous sandstones in the Miocene between this source region and the ∼350 km distant Expedition 322, using bathymetric constraints, we calculate that the sandstone beds represent minimum erupted magma volumes between ∼1 and 17 km3 (Dense Rock Equivalent (DRE)). We conclude that several large volume eruptions occurred during the Late Miocene time next to the collision zone of paleo-Honshu and Izu-Bonin arc and covered the entire Philippine Sea plate with meter thick, sheet-like pyroclastic deposits that are now subducted in the Nankai subduction zone. Abstract Copyright (2014), American Geophysical Union. All Rights Reserved.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; Alkaline earth metals; Alteration; Asia; Bathymetry; Biogenic structures; Bioturbation; Cenozoic; Chemical composition; Clastic rocks; Claystone; Electron probe data; Expedition 322; Expedition 333; Explosive eruptions; Far East; Honshu; Honshu Arc; IODP Site C0011; IODP Site C0012; Igneous rocks; Ignimbrite; Integrated Ocean Drilling Program; Island arcs; Isotope ratios; Isotopes; Izu-Bonin Arc; Japan; Kii Peninsula; Lead; Metals; Miocene; NanTroSEIZE; Nankai Trough; Nd-144/Nd-143; Neodymium; Neogene; North Pacific; Northwest Pacific; Pacific Ocean; Pb-206/Pb-204; Pb-207/Pb-204; Philippine Sea; Pyroclastics; Radioactive isotopes; Rare earths; Sandstone; Sedimentary rocks; Sedimentary structures; Shikoku Basin; Sr-87/Sr-86; Stable isotopes; Strontium; Subduction zones; Submarine volcanoes; Tertiary; Trace elements; Tuff; Upper Miocene; Volcanic rocks; Volcaniclastics; Volcanism; Volcanoes; West Pacific
Coordinates: N300000 N360000 E1420000 E1320000
Record ID: 2014098676
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom, Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union