International Ocean Discovery Program Expedition 351 preliminary report; Izu-Bonin-Mariana Arc origins; continental crust formation at an intraoceanic arc; foundation, inception, and early evolution; 30 May-30 July 2014

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doi: 10.14379/iodp.pr.351.2015
Author(s): Arculus, Richard; Ishizuka, Osamu; Bogus, Kara; Drab, Laureen; Aljahdali, Mohammed H.; Bandini, Alexandre N.; Barth, Andrew P.; Brandl, Philipp A.; Guerra, Rodrigo do Monte; Gurnis, Michael; Hamada, Morihisa; Hickey-Vargas, Rosemary L.; Jiang Fuqing; Kanayama, Kyoko; Kender, Sev; Kusano, Yuki; Li He; Loudin, Lorne C.; Maffione, Marco; Marsaglia, Kathleen M.; McCarthy, Anders; Meffre, Sebastien; Morris, Antony; Savov, Ivan P.; da Silva, Clara A. Sena; Tepley, Frank J., III; van der Land, Cees; Yogodzinski, Gene M.; Zhang Zhaohui
Internaitonal Ocean Discovery Program, Expedition 351 Scientists, College Station, TX
Author Affiliation(s): Primary:
Australian National University, Research School of Earth Sciences, Australia
Other:
Geological Survey of Japan, Japan
Texas A&M University, United States
Lamont-Doherty Earth Observatory, United States
Florida State University, United States
University of Western Australia, Australia
Indiana University-Purdue University Indianapolis, United States
University of Erlangen-Nuremberg, Germany
University of Vale do Rio dos Sinos, Brazil
California Institute of Technology, United States
Japan Agency for Marine-Earth Science and Technology, Japan
Florida International University, United States
Chinese Academy of Sciences, Institute of Oceanology, China
Kanazawa University, Japan
British Geological Survey, United Kingdom
Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, China
University of New Hampshire, United States
Utrecht University, Netherlands
California State University, Northridge, United States
University of Lausanne, Switzerland
University of Tasmania, Australia
Plymouth University, United Kingdom
University of Leeds, United Kingdom
Universidade de Aveiro, Portugal
Oregon State University, United States
University of Newcastle, United Kingdom
University of South Carolina, United States
Nanjing University, China
Source: Preliminary Report (International Ocean Discovery Program), Vol.351, 66p. Publisher: International Ocean Discovery Program, College Station, TX, United States. ISSN: 2372-9562
Note: In English. 84 refs.
Summary: The intraoceanic Izu-Bonin-Mariana (IBM) arc in the western Pacific has been intensively examined over the past few decades, and the outlines of its overall tectonic and magmatic history have been revealed. Arc inception occurred at ∼52 Ma, concurrent with a major change in the motion of the Pacific plate. Rifting of the active volcanic axis took place at ∼25 Ma, with accompanying seafloor spreading and eastward migration of the active volcanic front forming a volcanically inactive remnant arc (Kyushu-Palau Ridge; KPR). The Amami Sankaku Basin (ASB) flanks the northern KPR; the ASB seafloor has a simple structure comprising ∼1.5 km of sediment overlying igneous oceanic crust. International Ocean Discovery Program Expedition 351 targeted the ASB anticipating recovery of the sedimentary record of the earliest stages of arc inception and evolution of the northern IBM arc. Igneous basement samples would permit determination of the petrological, geochemical, and age characteristics of the pre-KPR crust in the region, from which the geochemical composition of the mantle prior to IBM arc inception and growth could be inferred. The expedition successfully accomplished its primary and most of its secondary objectives at Site U1438 in 4700 m water dept h. Drilling penetrated 1461 m of sediment and 150 m of variably altered and veined aphyric to sparsely phyric tholeiitic basalt lava flows, which form the uppermost igneous oceanic basement (lithostratigraphic Unit 1). Four sedimentary units have been established in the sedimentary column above basement, described here from oldest to youngest. Lithostratigraphic Unit IV (99.7 m) consists of early Eocene mudstone , tuffaceous siltstone, breccia-conglomerate, sandstone, and radiolarian-bearing mudstone. The oldest fossil (radiolarian) age is 50-53 Ma (Core 351-U1438E-63R-1; 40 m above basement). Lithostratigraphic Unit III (1046 m) consists of Eocene-Oligocene tuffaceous mudstone, tuffaceous sandstone, sandstone with gravel, and breccia-conglomerate with pebble/cobble-sized volcanic and sedimentary rock clasts. Lithostratigraphic Unit II (139.4 m) is Oligocene tuffaceous mudstone, siltstone, and fine sandstone with localized slumping. Lithostratigraphic Unit I (160.3 m) is latest Oligocene to recent mud and ooze of terrigenous and biogenic origin, with interspersed discrete tephra layers. In addition to the fossil age constraint, in situ downhole temperature measurements and thermal conductivity measurements on core material from Unit I give a calculated heat flow of 73.7 mW/m 2 , implying a thermal age for the underlying lithosphere of 40-60 Ma. The recovery at Site U1438 of an extensive sediment sequence of early Eocene age in Unit IV, coeval with the putative initiation of the IBM arc at ∼52 Ma determined by radiometric dating of fore-arc igneous samples, will allow comprehensive analysis of the provenance, geochemical and petrological characteristics, and style of earliest arc magmatic activity in the KPR. The geochemical and petrological equivalence of the Unit 1 lava flows with the "fore-arc basalts" of the IBM fore arc has critical implications regarding the style of magmatism accompanying arc initiation and the lateral (across-strike) extent of this type of igneous activity. The apparent absence of boninite at Site U1438, however, may indicate petrologic provinciality was established within the first few million years of IBM magmatism.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; 18 Geophysics, Solid-Earth; Absolute age; Algae; Ar/Ar; Basalts; Basement; Biostratigraphy; Boreholes; Cenozoic; Chemostratigraphy; Cores; Cretaceous; Crust; Expedition 351; Foraminifera; Gabbros; Geophysical methods; Geophysical profiles; Geophysical surveys; IODP Site U1438; Igneous rocks; International Ocean Discovery Program; Invertebrata; Izu-Bonin Arc; Lithosphere; Lithostratigraphy; Magnetostratigraphy; Mariana Islands; Mesozoic; Microfossils; Micronesia; Nannofossils; North Pacific; Northwest Pacific; Oceania; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleomagnetism; Philippine Sea Plate; Physical properties; Plantae; Plate tectonics; Plutonic rocks; Protista; Quaternary; Radiolaria; Rifting; Sedimentary rocks; Seismic methods; Seismic profiles; Seismic stratigraphy; Stratigraphic units; Subduction; Surveys; Tertiary; Volcanic rocks; Volcaniclastics; Volcanism; Well logs; West Pacific
Coordinates: N272300 N272300 E1341900 E1341900
Record ID: 2015099188
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