Site U1438

Arculus, R. J.; Ishizuka, Osamu; Bogus, Kara; Aljahdali, Mohammed H.; Bandini-Maeder, Alexandre N.; Barth, Andrew P.; Brandl, Philipp A.; Guerra, Rodrigo do Monte; Drab, L.; Gurnis, Michael; Hamada, Mareomi; Hickey‐Vargas, Rosemary; Jiang, Fangming; Kanayama, Kyoko; Kender, Sev; Kusano, Yuki; Li, H.; Loudin, Lorne C.; Maffione, Marco; Marsaglia, Kathleen M.; McCarthy, Anders; Meffre, Sébastien; Morris, A.; Neuhaus, Martin; Savov, Ivan P.; Silva, C.A. Sena Da; Tepley, F. J.; Land, Cees van der; Yogodzinski, G. M.; Zhang, Z.

doi:10.14379/iodp.proc.351.103.2015

Cited by 11 publications

(27 citation statements)

References 24 publications

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“…(i) δD. Division of lithology units is based on Arculus, Ishizuka, Bogus, and the Expedition 351 Scientists (). Error bars for major and trace elements are estimated at 1%.…”

Section: Methodsmentioning

confidence: 99%

“…Rifting of the active volcanic axis and accompanied seafloor spreading as well as the eastward migration of the active volcanic front took place at ~25 Ma, resulting in the formation of the KPR, volcanically inactive remnant arc (Arculus, Ishizuka, Bogus, & the Expedition 351 Scientists, ; Ishizuka et al, ). The locus of arc magmatism shifted eastward, and consequently, the distance between the KPR chain of volcanoes and the present‐day trench is much greater than originally.…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…The lithologic sequence recorded the formation of the IBM arc basement and the subsequent history of the early IBM arc from arc initiation to arc rifting and back‐arc basin formation at about 25 Ma (Arculus, Ishizuka, Bogus, Gurnis, et al, ; Arculus, Ishizuka, Bogus, & the Expedition 351 Scientists, ). Such large‐scale tectonic activities shall be reflected in the chemical and isotopic compositions of sediment pore waters.…”

Section: Introductionmentioning

confidence: 99%

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Rapid Shifts in Chemical and Isotopic Compositions of Sediment Pore Waters in the Amami Sankaku Basin in Response to Initial Arc Rifting in the Mid‐Oligocene

Zhao-hui

2020

Geochem Geophys Geosyst

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Pore waters were recovered from the sediment cores drilled in the back‐arc Amami Sankaku Basin (ASB) during the International Ocean Discovery Program Expedition 351. The sediment sequence is composed of the recent mud and ooze from late Oligocene/early Miocene accumulated at 7 m/Ma and rapid deposition of thick volcaniclastic sequence at 50 m/Ma. Such variations are reflected in the evolutions of chemical and isotopic compositions of pore waters. Cl and Ca concentrations in pore waters increased rapidly with depth and became enriched in the deep portion. Before arc rifting, extremely high deposition rates of volcaniclastic gravity‐flow sediments from the nearby Kyushu‐Palau arc into the ASB resulted in strong alteration, removing Mg and Si from pore waters. Mg concentrations were initially almost zero but abruptly shifted to substantial increases after ~29.5 Ma, indicating extended rifting of the active volcanic axis from the ASB. The δ18O and δD values of pore waters also evolved from more depleted and wide range to more positive and narrow range as a response to reduced alteration and increasing influence of seawater. Concentrations of Si and Mn in pore waters rapidly increased since ~29.5 Ma but suddenly declined at ~17.5 Ma due to the cessation of input of volcaniclastic materials. Covariations of Ca and Mg in pore waters are very similar to those in the back‐arc West Philippine Basin but significantly different from those in the Izu‐Bonin fore‐arc basin. Variations in chemical and isotopic compositions of pore waters can assist the reconstruction of tectonic activities.

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“…(i) δD. Division of lithology units is based on Arculus, Ishizuka, Bogus, and the Expedition 351 Scientists (). Error bars for major and trace elements are estimated at 1%.…”

Section: Methodsmentioning

confidence: 99%

Section: Regional Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rapid Shifts in Chemical and Isotopic Compositions of Sediment Pore Waters in the Amami Sankaku Basin in Response to Initial Arc Rifting in the Mid‐Oligocene

Zhao-hui

2020

Geochem Geophys Geosyst

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Section: Introductionmentioning

confidence: 99%

“…One of the primary aims of IODP Expedition 351 was to target the sedimentary and volcaniclastic record at Site U1438 to constrain the evolution of the arc following inception at ~50 Ma (Arculus et al, ). Sediments and sedimentary rocks recovered at Site U1438 up to 1461 m below seafloor (mbsf) were separated into four distinct lithostratigraphic units (Units I to IV; Arculus et al, ) and overly a unit of igneous basement (Unit 1: 1461–1611 mbsf). The deeper portions of the volcaniclastic and sedimentary record in the core (Unit III: ~310–1361 mbsf, and IV: ~1361–1461 mbsf) are primarily related to the Paleogene Izu‐Bonin arc developed at the KPR (50 to 25 Ma; Brandl et al, ).…”

Section: Introductionmentioning

confidence: 99%

Isotopic Characteristics of Neogene‐Quaternary Tephra From IODP Site U1438: A Record of Explosive Volcanic Activity in the Kyushu‐Ryukyu Arc

McCarthy

Yogodzinski

Tepley

et al. 2019

Geochem Geophys Geosyst

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International Ocean Discovery program (IODP) Site U1438 is located within the Amami‐Sankaku Basin, ~50 km SW of the Kyushu‐Palau Ridge and ~500 km SE of the present‐day volcanic front of the Kyushu‐Ryukyu arc. Thirty‐eight rhyolitic tephra layers (1–15 cm thick) deposited over the last 4 Myr were recovered at this site. Representative ash layers dominated by unaltered, colorless glass shards reaching 100–300 μm in size, in association with rare pyroxene, amphibole, biotite, and zircon, were sampled for isotopic analysis. The isotopic compositions of the tephra have a narrow range in 87Sr/86Sr (0.704 to 0.706), 206Pb/204Pb (18.32 to 18.46), 207Pb/204Pb (15.57 to 15.62), and 208Pb/204Pb (38.46 to 38.75) and are more variable in εNd (−3.5 to +4.8) and εHf (+2.0 to +13.3). This record indicates the tephra were not sourced from the Izu‐Bonin‐Mariana arc or from Central Japan but derived from felsic volcanism from the Kyushu‐Ryukyu arc. The 4.8‐km‐deep Amami‐Sankaku Basin was located up to 600–900 km from the Kyushu‐Ryukyu arc over the last 4 Ma, which is significantly more distal than other drill sites from which extensive tephra layers sourced from SW Japan have been recovered. Site U1438 tephra are thus likely related to widely distributed (M > 6) rhyolitic eruptions. We propose the unique tephra record and high‐precision isotope analysis of recovered tephra from Site U1438 can be used as an important marker to identify submerged calderas within the Ryukyu arc and/or constrain the history of activity (>1 Ma) of major calderas‐forming eruptions within the Kyushu‐Ryukyu arc.

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The onset of fabric development in deep marine sediments

Maffione

Morris

2017

Earth and Planetary Science Letters

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Post-depositional compaction is a key stage in the formation of sedimentary rocks that results in porosity reduction, grain realignment and the production of sedimentary fabrics. The progressive time-depth evolution of the onset of fabric development in deep marine sediments is poorly constrained due to the limited quantity and resolution of existing data. Here we present high-resolution anisotropy of magnetic susceptibility (AMS) results from clay-rich deep marine sediments recovered at International Ocean Discovery Program Site U1438 (Philippine Sea). AMS is a petrofabric tool sensitive to the preferred orientation of grains in rocks. Down-section variations of AMS parameters, density, porosity and the inclination of magnetic remanences demonstrate that fabrics develop in response to compaction and dewatering but also that they do not develop progressively with depth below the mudline. Instead, a horizontal foliation first forms at 83 mbsf once the sediment load reaches an effective stress threshold for the onset of compaction and is then continuously enhanced down to 113 mbsf, defining a 30 m-thick 'initial compaction window'. The magnetostratigraphic age model for IODP Site U1438 indicates a delay of 5.7 Ma in initial fabric formation following sediment deposition, with strongly defined fabrics then taking an additional 6.5 Ma to develop.

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Site U1438

Abstract: Background and objectives 3 Operations 8 Lithostratigraphy 28 Biostratigraphy 35 Geochemistry 41 Paleomagnetism 55 Physical properties and downhole measurements 63 References 101 2H

Cited by 11 publications

References 24 publications

Rapid Shifts in Chemical and Isotopic Compositions of Sediment Pore Waters in the Amami Sankaku Basin in Response to Initial Arc Rifting in the Mid‐Oligocene

Rapid Shifts in Chemical and Isotopic Compositions of Sediment Pore Waters in the Amami Sankaku Basin in Response to Initial Arc Rifting in the Mid‐Oligocene

Isotopic Characteristics of Neogene‐Quaternary Tephra From IODP Site U1438: A Record of Explosive Volcanic Activity in the Kyushu‐Ryukyu Arc

The onset of fabric development in deep marine sediments

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