Making and breaking an island arc; a new perspective from the Oligocene Kyushu-Palau Arc, Philippine Sea

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doi: 10.1029/2010GC003440
Author(s): Ishizuka, Osamu; Taylor, Rex N.; Yuasa, Makoto; Ohara, Yasuhiko
Author Affiliation(s): Primary:
Geological Survey of Japan, Tsukuba, Japan
Other:
University of Southampton, United Kingdom
Hydrographic and Oceanographic Department of Japan, Japan
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 12(5). Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. Includes appendices. 97 refs.; illus., incl. 7 tables
Summary: The Kyushu-Palau Ridge (KPR) is a 2600 km long remnant island arc that is separated from the active Izu-Bonin-Mariana (IBM) arc by a series of spreading and rift basins. We present 40Ar/39Ar ages and geochemical data for the entire length of the Kyushu-Palau arc as well as for the conjugate arc which is stranded within the IBM fore arc. New 40Ar/39Ar ages indicate that the KPR was active between 25 and 48 Ma, but the majority of the exposed volcanism occurred in the final phase, between 25 and 28 Ma. Rifting of the Kyushu-Palau arc to form the Shikoku and Parece Vela basins occurred simultaneously along the length of the arc (circa 25 Ma), and at a similar distance from the trench. Unlike the IBM, the KPR has only limited systematic along-arc geochemical trends. Two geochemical components within the KPR indicate an origin in the suprasubduction mantle. First, EM-1-like lavas are identified in a restricted section of the arc, suggesting a localized heterogeneity. Second, EM-2-like arc volcanoes formed on juvenile West Philippine Basin crust, potentially reflecting ingress of mantle from the then active EM-2 province which lies in the west. Another geochemical heterogeneity is found at the KPR-Daito Ridge intersection where the arc developed on preexisting Cretaceous Daito Ridge crust. The geochemical characteristics at this intersection likely result from the involvement of sub-Daito Ridge lithospheric mantle. Subduction flux beneath the KPR generally matches post-45 Ma Eocene/Oligocene lavas in the IBM fore arc, involving fluids and melts derived from altered igneous crust.
Year of Publication: 2011
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 18 Geophysics, Solid-Earth; Absolute age; Ar/Ar; Basalts; Cenozoic; Cretaceous; DSDP Site 296; DSDP Site 448; Daito Ridge; Deep Sea Drilling Project; Eocene; Geochemistry; IPOD; Igneous rocks; Island arcs; Isotope ratios; Isotopes; Izu-Bonin Arc; Kyushu-Palau Ridge; Lead; Leg 126; Leg 185; Leg 195; Leg 31; Leg 59; Lithosphere; Mantle; Mariana Islands; Mesozoic; Metals; Micronesia; Mid-ocean ridge basalts; North Pacific; Northwest Pacific; ODP Site 1149; ODP Site 1201; ODP Site 792; ODP Site 793; ODP Site 801; Ocean Drilling Program; Ocean-island basalts; Oceania; Oligocene; Pacific Ocean; Paleogene; Parece Vela Basin; Pb-206/Pb-204; Pb-207/Pb-204; Philippine Sea; Pigafetta Basin; Radioactive isotopes; Shikoku Basin; Stable isotopes; Tertiary; Volcanic rocks; West Pacific; West Philippine Basin
Coordinates: N162027 N162028 E1345227 E1345227
N292025 N292025 E1333131 E1333131
N191700 N191800 E1350600 E1350500
Record ID: 2012021755
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