Missing Oligocene crust of the Izu-Bonin Arc; consumed or rejuvenated during collision?

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doi: 10.1093/petrology/egq002
Author(s): Tamura, Yoshihiko; Ishizuka, Osamu; Aoike, Kan; Kawate, Shinichi; Kawabata, Hiroshi; Chang, Qing; Saito, Satoshi; Tatsumi, Yoshiyuki; Arima, Makoto; Takahashi, Masaki; Kanamaru, Tatsuo; Kodaira, Shuichi; Fiske, Richard S.
Author Affiliation(s): Primary:
Japan Agency for Marine-Earth Evolution, Institute for Research on Earth Evolution, Yokosuka, Japan
Geological Survey of Japan, Japan
Musashi High School, Japan
Yokohama National University, Japan
Nihon University, Japan
National Museum of Natural History, United States
Volume Title: Journal of Petrology
Source: Journal of Petrology, 51(4), p.823-846. Publisher: Oxford University Press, Oxford, United Kingdom. ISSN: 0022-3530 CODEN: JPTGAD
Note: In English
Summary: The ∼50 Myr old Izu-Bonin-Mariana (IBM) arc consists mostly of Oligocene middle and lower crust that underlies the upper crust; these units are in turn covered by Quaternary volcanic rocks. Seismic imaging, forearc geology, Ocean Drilling Program drilling and magnetic anomalies suggest that most IBM arc crust was created in Eocene-Oligocene times. However, remnants of this old crust have never been found at the northern end of the arc, where it is colliding with the Honshu arc (Izu collision zone). Two batholiths in this collision zone (the Tanzawa tonalites and the Kofu Granitic Complex) were emplaced during the Miocene (4-17 Ma). Major elements, Zr/Y, rare earth element ratios and normalized abundance patterns, and Sr-Nd isotopic data indicate that these plutonic bodies are compositionally similar to the Oligocene IBM volcanic rocks, and that they are dissimilar to the Miocene, Pliocene and Quaternary IBM lavas and volcaniclastic rocks. We suggest that the Miocene plutonic rocks in the Izu collision zone were derived from partially melted Oligocene middle crust. A model is proposed in which IBM arc middle crust in the collision zone was partially melted during the collision and then intruded into the overlying upper crust of the Honshu and IBM arcs. This resulted in the complete loss of chronological information related to their original source.
Year of Publication: 2010
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; Asia; Cenozoic; Chemical ratios; Crust; Diorites; Far East; Geochemistry; Granites; Honshu; Igneous rocks; Izu-Bonin Arc; Japan; Kofu Complex; Leg 126; Lithogeochemistry; Lower crust; Middle crust; North Pacific; Northwest Pacific; ODP Site 787; ODP Site 792; ODP Site 793; Ocean Drilling Program; Oligocene; Pacific Ocean; Paleogene; Plutonic rocks; Tanzawa Mountains; Tertiary; Tonalite; West Pacific
Coordinates: N322230 N322231 E1404439 E1404438
N322355 N322359 E1402249 E1402246
N310619 N310621 E1405217 E1405215
Record ID: 2011045356
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