Early history of the Izu-Bonin-Mariana Arc system; evidence from Belau and the Palau Trench

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doi: 10.1111/j.1440-1738.1998.00210.x
Author(s): Hawkins, James W.; Castillo, Paterno R.
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, Geological Research Division, La Jolla, CA, United States
Other:
University of Texas at Dallas, United States
Volume Title: Izu-Bonin-Mariana Arc system
Volume Author(s): Stern, Robert J., prefacer; Arima, Makoto
Source: Izu-Bonin-Mariana Arc system, prefaced by Robert J. Stern and Makoto Arima. Island Arc, 7(3), p.559-578. Publisher: Wiley Blackwell on behalf of Geological Society of Japan, Tsukuba, Japan. ISSN: 1038-4871
Note: In English. 56 refs.; illus., incl. 2 tables, geol. sketch map
Summary: Volcanic rocks of the Kyushu-Palau Ridge (KPR) from Deep Sea Drilling Project (DSDP) site 448 and from Belau comprise a low-to-medium-K arc tholeiitic series. Belau rocks include (probable) Mid-Eocene low-Ca type-3 boninite and pre-Early Oligocene-Early Miocene low-K arc tholeiitic basalt, basaltic andesite, andesite and dacite. Palau Trench samples include sparsely phyric high-Mg, -Cr and -Ni rocks which resemble the Belau boninite and Izu-Bonin-Mariana (IBM) system boninites. The high-Mg Palau Trench samples also resemble other primitive arc lavas (e.g. arc picrites). Their chemistry suggests an origin involving steep thermal gradients in multiply depleted mantle. Subduction of hot, young lithosphere under a young hot upper plate is postulated to explain this occurrence. The KPR is inferred to be the source of Eocene boninite and arc tholeiitic terranes presently in forearc regions of the IBM system. A model is presented here showing how many IBM boninites may have originated in a small area near Belau. These have migrated eastward by episodic back-arc opening accompanying eastward migration of arcs and trenches. Oldest known KPR rocks (ca 47.5 Ma at DSDP site 296), and presumed KPR-derived exotic terranes of Guam (ca 43.8 Ma), presage the postulated Eocene (ca 42-43 Ma) change in Pacific plate motion invoked as the cause of subduction initiation at the KPR. The KPR has been rotated more than 40° clockwise since the Eocene, thus the age mismatch may indicate a different tectonic style, for example transtension or transpression, in earliest KPR history.
Year of Publication: 1998
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; 18 Geophysics, Solid-Earth; Andesites; Babelduap Island; Basalts; Boninite; Caroline Islands; Cenozoic; DSDP Site 296; DSDP Site 448; Dacites; Deep Sea Drilling Project; Eocene; IPOD; Igneous rocks; Island arcs; Izu-Bonin Arc; Kyushu-Palau Ridge; Lava; Leg 125; Leg 31; Leg 59; Lithosphere; Magmatism; Mantle; Mariana Arc; Micronesia; Movement; North Pacific; Northwest Pacific; ODP Site 786; Ocean Drilling Program; Oceania; Oligocene; Pacific Ocean; Palau; Palau Trench; Paleogene; Paleomagnetism; Philippine Sea; Picrite; Plate tectonics; Rotation; Subduction; Tertiary; Tholeiitic basalt; Trace elements; Volcanic rocks; West Pacific
Coordinates: N065500 N080500 E1345000 E1341500
N060000 N100000 E1380000 E1340000
Record ID: 2012050272
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