Geochronology of alkali volcanism in Oki-Dogo Island, Southwest Japan: Geochemical evolution of basalts related to the opening of the Japan Sea.

Uto, Kozo; Takáhashi, Eiichi; Nakamura, Eizo; Kaneoka, Ichiro

doi:10.2343/geochemj.28.431

Cited by 41 publications

(35 citation statements)

References 34 publications

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“…Eby (1990) In an earlier section, we noted that the main phase of late Miocene igneous activity on Oki Dozen overlaps in part with the Oki Trachyte Rhyolite Group of Oki Dogo ( Fig. 2; Uto et al, 1994). Despite the name, the Oki Trachyte Rhyo lite Group contains mafic as well as felsic rocks .…”

Section: Petrogenesis Of Central Cone Trachytementioning

confidence: 99%

“…Despite the name, the Oki Trachyte Rhyo lite Group contains mafic as well as felsic rocks . Uto et al (1994) showed that mafic and differentiated rocks were contempora neous. The chemistry of the Oki Trachyte-Rhyolite Group (Uto et al, 1994;Morris, unpublished data) is compared to somma, parasitic and dike phase data from Oki Dozen in Figs.…”

Section: Petrogenesis Of Central Cone Trachytementioning

confidence: 99%

“…2. Summary of K/Ar whole-rock age data for late Miocene igneous rocks of Oki Dozen (Wada et al ., 1990;Morris et al, 1990Morris et al, , 1997 and late Miocene to Pliocene alkalic volcanic rocks from Oki Dogo (Fujimaki et al ., 1989;Uto et al, 1994). Height of box is proportional to number of analyses, which is also shown (n) .…”

Section: Introductionmentioning

confidence: 99%

“…Weight percent K20 vs. Na20. Shaded circles are analyses from the Oki Trachyte-Rhyolite Group of Oki Dogo (Xu, 1988;Uto et al, 1994;Morris, unpublished). Other symbols as Fig .…”

Section: Introductionmentioning

confidence: 99%

“…Uto et al (1994) recently reviewed the chronology of Miocene to Recent alkalic volcan ism from Oki Dogo. They identified four phases of alkalic igneous activity at 18-19 Ma, 5.5-5.4 Ma, 4.4-2.4 Ma, and 1.33-0.55 Ma, and com mented that none of these ages were contempora neous with volcanic activity on Oki Dozen.…”

Section: Introductionmentioning

confidence: 99%

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Age relations and petrology of alkalic igneous rocks from Oki Dozen, Southwest Japan.

Morris¹,

Itaya²,

Iizumi³

et al. 1997

Geochem. J.

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K/Ar age data, whole-rock major, trace and rare earth element geochemistry, 87Sr/86Sr and 143Nd/144Nd isotope chemistry, and computer modelling have been used to clarify the timing and petrogenesis of late Miocene igneous activity on Oki Dozen Island in the Japan Sea. Commencing at about 7 Ma, quartz syenite was intruded on the southeastern part of present-day Nishinoshima. At the same time, compositionally similar magma (trachyte) was erupted as lava and pyroclastic flows. At approximately 6 Ma, alkali olivine basalt-trachyandesite was erupted, forming a volcanic shield (somma phase). Following this, the locus of volcanic activity, and the composition of the magma changed, with eruption of trachyte and rhyolite from satellite vents (parasitic phase). Dikes, compositionally similar to extruded magma, were intruded throughout this volcanic episode. K/Ar dating cannot resolve the individual phases of volcanic activity, which partly overlaps with late Miocene volcanism on Oki Dogo. The composition of somma and parasitic phase volcanics were controlled by fractionation of observed phenocryst phases, but decoupling of trace elements and small isotopic shifts indicate the transition from somma to parasitic volcanism was not a closed system process. Syenite and comagmatic central cone trachyte are compositionally similar to anorogenic granitoids, and may result from melting of a felsic lower crust by upwelling basaltic magma. Despite weak age overlap, divergent trace element and isotopic trends, and small differences in rare earth element chemistry indicate that alkalic volcanic rocks on Oki Dozen and Oki Dogo tapped different mantle sources.

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Section: Petrogenesis Of Central Cone Trachytementioning

confidence: 99%

Section: Petrogenesis Of Central Cone Trachytementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Weight percent K20 vs. Na20. Shaded circles are analyses from the Oki Trachyte-Rhyolite Group of Oki Dogo (Xu, 1988;Uto et al, 1994;Morris, unpublished). Other symbols as Fig .…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Age relations and petrology of alkalic igneous rocks from Oki Dozen, Southwest Japan.

Morris¹,

Itaya²,

Iizumi³

et al. 1997

Geochem. J.

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Diverse magmatic effects of subducting a hot slab in SW Japan: Results from forward modeling

Kimura

Gill

Kunikiyo³

et al. 2014

Geochem Geophys Geosyst

211

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In response to the subduction of the young Shikoku Basin of the Philippine Sea Plate, arc magmas erupted in SW Japan throughout the late Cenozoic. Many magma types are present including ocean island basalt (OIB), shoshonite (SHO), arc-type alkali basalt (AB), typical subalkalic arc basalt (SAB), high-Mg andesite (HMA), and adakite (ADK). OIB erupted since the Japan Sea back-arc basin opened, whereas subsequent arc magmas accompanied subduction of the Shikoku Basin. However, there the origin of the magmas in relation to hot subduction is debated. Using new major and trace element and Sr-Nd-Pb-Hf isotope analyses of 324 lava samples from seven Quaternary volcanoes, we investigated the genetic conditions of the magma suites using a geochemical mass balance model, Arc Basalt Simulator version 4 (ABS4), that uses these data to solve for the parameters such as pressure/temperature of slab dehydration/melting and slab flux fraction, pressure, and temperature of mantle melting. The calculations suggest that those magmas originated from slab melts that induced flux melting of mantle peridotite. The suites differ mostly in the mass fraction of slab-melt flux, increasing from SHO through AB, SAB, HMA, to ADK. The pressure and temperature of mantle melting decreases in the same order. The suites differ secondarily in the ratio of altered oceanic crust to sediment in the source of the slab melt. The atypical suites associated with hot subduction result from unusually large mass fractions of slab melt and unusually cool mantle temperatures.

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Sediment‐enriched adakitic magmas from the Daisen volcanic field, Southwest Japan

Feineman

Moriguti

Yokoyama

et al. 2013

Geochem Geophys Geosyst

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[1] The Quaternary Southwest Japan Arc is a product of subduction of the hot, young Philippine Sea Plate beneath the Eurasian Continental Plate. The magmas erupted from the Southwest Japan Arc belong to a category of magmas commonly referred to as ''adakites'' or ''adakitic magmas''. These magmas show trace element evidence for interaction with garnet at depth, and may be associated with partial melting of subducted altered oceanic crust. Also found throughout the southern Sea of Japan region are alkali basalts with little apparent connection to the subduction zone. We have determined major element, trace element, and Sr, Nd, Pb, and U-Th isotopic compositions for a bimodal suite of lavas erupted at the Daisen volcanic field in the Southwest Japan Arc. These magmas consist of mildly alkaline basalts and a calcalkaline intermediate suite, separated by a $10 wt.% silica gap. The intermediate magmas show trace element and isotopic evidence for interaction with garnet, consistent with partial melting of the hot, young ($20 Ma) Philippine Sea Plate. The Daisen intermediate magmas are distinct from other adakitic magmas in their radiogenic isotopic characteristics, consistent with a significant contribution ($25%) from subducted Nankai Trough sediments. Our data suggest that the basalts erupted at the Daisen volcanic field are not parental to the intermediate magmas, and contain a small contribution of EM1-like mantle common in Sea of Japan alkali basalts but not apparent in the Daisen intermediate magmas.

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Geochronology of alkali volcanism in Oki-Dogo Island, Southwest Japan: Geochemical evolution of basalts related to the opening of the Japan Sea.

Cited by 41 publications

References 34 publications

Age relations and petrology of alkalic igneous rocks from Oki Dozen, Southwest Japan.

Age relations and petrology of alkalic igneous rocks from Oki Dozen, Southwest Japan.

Diverse magmatic effects of subducting a hot slab in SW Japan: Results from forward modeling

Sediment‐enriched adakitic magmas from the Daisen volcanic field, Southwest Japan

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