Picritic basalt from the Miocene Yoka Formation in the Tango Peninsula, Kyoto Prefecture, south-western Japan.

明, 石渡; 美絵, 今坂

doi:10.5575/geosoc.108.10_671

Cited by 7 publications

(3 citation statements)

References 20 publications

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“…In the Tango Peninsula (Fig. ), the Yoka Formation contains andesite and basalt composed of olivine ± clinopyroxene ± orthopyroxene basalt and clinopyroxene–orthopyroxene andesite (Ishiwatari & Imasaka ). The radiometric ages indicate that the Yoka Formation was deposited at about 21–18 Ma (Furuyama et al .…”

Section: Discussionmentioning

confidence: 99%

Petrographic study of the Miocene Mizunami Group, Central Japan: Detection of unrecognized volcanic activity in the Setouchi Province

Sasao

2013

Island Arc

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A petrographic study of sandstones from the Miocene Mizunami Group in Central Japan has been performed on core samples from a single borehole, in order to evaluate the provenance of the sedimentary rock. Evaluation of the provenance is based on bulk mineral, heavy mineral and plagioclase contents and on whole rock chemical compositions. The sandstones studied are divisible into three types; the first type is characterized by the occurrence of biotite and plagioclase ranging from albite to oligoclase, the second type is characterized by the dominance of amphibole and labradorite with pyroxene (clinopyroxene > orthopyroxene), and the third type is characterized by the dominance of pyroxene (orthopyroxene > clinopyroxene) and andesine with lesser labradorite, bytownite and anorthite. The first type is interpreted to be derived from the basement granite, whereas the others were derived mostly from volcanic ash, judging from their mineral compositions. The volcanic activity that supplied the volcanic ash to the Mizunami Basin occurred in two phases, distinguishable by variations in their mineralogical and geochemical compositions, an indication of change in character of the volcanic activity. This petrographic study of the sandstones in the Mizunami Group suggests that unrecognized volcanic activity occurred around the Mizunami Basin, even though potential provenance of the volcanic ash has not yet been identified.

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Section: Discussionmentioning

confidence: 99%

Petrographic study of the Miocene Mizunami Group, Central Japan: Detection of unrecognized volcanic activity in the Setouchi Province

Sasao

2013

Island Arc

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“…The “Yakuno Ophiolite” identified by Dr. Ishiwatari has been internationally recognized as an ophiolite with an unusually thick oceanic crust (Ishiwatari, 1985a, 1985b; Ishiwatari, 1991). As a skilled field geologist with a strong background in petrology, Dr. Ishiwatari worked not only on the Yakuno Ophiolite but also on ophiolites in the French Alps (Ishiwatari, 1985c) and Russian Far East (Ishiwatari et al, 2003; Ishiwatari & Ichiyama, 2004), as well as on plume‐related accreted ocean‐island basalts (Ichiyama et al, 2008), and Miocene volcanic rocks formed during the opening of the Japan Sea (Ayalew & Ishiwatari, 2011; Ishiwatari & Imasaka, 2002). He also studied deep‐sea igneous rocks as a modern ophiolite analog (Ishiwatari, 1992; Ishiwatari et al, 2006).…”

Section: A Celebration Of the Career Of Akira Ishiwatarimentioning

confidence: 99%

Editorial for the thematic issue, “Orogens, ophiolites, and oceans: A snapshot of Earth's tectonic evolution”

et al. 2022

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“…Dashed arrows indicate the possible eclogitic and peridotitic sources. Data sources: Ethiopian LIP low-Ti and HT2 suits (Beccaluva et al, 2009); Abitibi komatiite (Barnes, 1985); Pioneer komatiite (Stiegler et al, 2012); Gorgona komatiite (Dietrich et al, 1981); Emeishan picrites (Kamenetsky et al, 2012); Siberian ferropicrite (Arndt et al, 1995); Karoo meimechite and ferropicrite Luttinen, 2008, 2010); West Greenland picrite (Larsen and Pedersen, 2000); Hawaii picrite (Wilkinson and Hensel 1988); Tonga boninite (Sobolev and Danyushevsky, 1994); Sorachi-Yezo picrite (Ichiyama et al, 2012); Tango picrite (Ishiwatari and Imasaka, 2002); depleted (D-type) and enriched (E-type) picrites from Mikabu belt (Ichiyama et al, 2014); high magnesian andesite (HMA) and tholeiite lava Noto Peninsula (López and Ishiwatari, 2002); Mongolian high magnesian andesite and picrite (Erdenesaihan et al, 2013).…”

Section: Primary Bulk-rock Nature Of the Meltmentioning

confidence: 99%

Ferropicrite from the Lalibela area in the Ethiopian large igneous province

Desta

Ayalew

Ishiwatari

et al. 2014

Journal of Mineralogical and Petrological Sciences

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Ferropicrite (FeO* = 14.0 wt% and MgO = 13.9 wt%) and picritic ferrobasalt (FeO* = 14.7 wt% and MgO = 10.8 wt%) lava flows are found near Lalibela in the Oligocene (~30 Ma) Ethiopian large igneous province (LIP) in association with ultratitaniferous transitional basalt and picrite of the second high-Ti (HT2) series. The dominant phenocryst in the studied samples is Mg-rich olivine (up to Fo 88.9) with high CaO contents (to 0.42 wt%) without any kink band structure, indicating that the olivines are crystallized from a magnesian melt. Spinel microphenocrysts and inclusions in olivine are characterized by extremely high Cr# (79-84), moderate Mg# (18-51), moderate Fe 3+ # (11-39) and high TiO 2 (3.6-14.8 wt%). The clinopyroxene phenocrysts are Mg#=74-88, TiO 2 = 0.84-1.82 wt%, and Al 2 O 3 = 1.2-3.2 wt% in the cores. The REE contents of clinopyroxenes display enrichment in LREE (La N /Yb N = 1.2-1.9) and MREE (Eu N /Yb N = 3.3-4.3) relative to HREE. Relative depletion of HFSE (e.g., Nb and Zr) is also observed. In general, these trace element characteristics of clinopyroxene are similar to those of the HT2 basalts. Some of the clinopyroxene crystals show strong reverse zoning with abrupt increase in Cr, Ni and Mg# from core to rim, which may be resulted from reaction of melt with mantle peridotite during magma ascent. Bulk rock chemistry of the studied samples exhibits very low Al 2 O 3 /TiO 2 (1.8-2.2) and high Zr/Y (8.2-10.2) ratios. These may indicate the important role for garnet during melting and that the lavas were formed by a small degree of partial melting which apparently contradicts to the high Cr# of spinel. In view of low Cr/Al ratio of the bulk rock, the high Cr# of spinel suggests very high temperature of the magma (and the mantle plume). The origin of these ferropicrite and picritic ferrobasalt could be attributed to high pressure partial melting of peridotite-eclogite (pyroxenite) mixture that possibly incorporated recycled oceanic crust components.

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Picritic basalt from the Miocene Yoka Formation in the Tango Peninsula, Kyoto Prefecture, south-western Japan.

Cited by 7 publications

References 20 publications

Petrographic study of the Miocene Mizunami Group, Central Japan: Detection of unrecognized volcanic activity in the Setouchi Province

Petrographic study of the Miocene Mizunami Group, Central Japan: Detection of unrecognized volcanic activity in the Setouchi Province

Editorial for the thematic issue, “Orogens, ophiolites, and oceans: A snapshot of Earth's tectonic evolution”

Ferropicrite from the Lalibela area in the Ethiopian large igneous province

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