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Dive into the research topics where Yuji Ichiyama is active.

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Featured researches published by Yuji Ichiyama.


Geology | 2012

Picrites in central Hokkaido: Evidence of extremely high temperature magmatism in the Late Jurassic ocean recorded in an accreted oceanic plateau

Yuji Ichiyama; Akira Ishiwatari; Jun-Ichi Kimura; Ryoko Senda; Hiroshi Kawabata; Yoshiyuki Tatsumi

The Sorachi-Yezo belt, central Hokkaido, Japan, is composed of voluminous tholeiitic basaltic volcanics, and has been thought to be accreted fragments of an oceanic plateau formed in the Late Jurassic Pacific Ocean. Picrites have been reported as pillow lava and hyaloclastite from the Sorachi-Yezo belt. These picrites are characterized by very magnesian olivine phenocrysts (up to Fo [=100* Mg/(Mg+Fe)] = 94.1), which indicate that the primary magma was unusually Mg rich. The estimated MgO of the primary magma and the mantle potential temperature are as high as 29 wt% and 1700 °C, respectively, comparable to those of the Neoarchean komatiites, and higher than those of the Gorgona komatiites and picrites. The rare earth element patterns of the Sorachi-Yezo picrites are divided into two groups that are chemically akin to the Neoarchean komatiites and Gorgona komatiites and picrites, indicating different melting regimes in an extremely hot mantle plume. The Sorachi-Yezo picrites provide evidence for extremely high temperature magmatism, like that of Archean komatiite, caused by melting of the hottest mantle plume among the Phanerozoic oceanic large igneous provinces.


Lithos | 2008

Petrogenesis of greenstones from the Mino–Tamba belt, SW Japan: Evidence for an accreted Permian oceanic plateau

Yuji Ichiyama; Akira Ishiwatari; Kazuto Koizumi


Lithos | 2006

Geochemical and isotopic constraints on the genesis of the Permian ferropicritic rocks from the Mino–Tamba belt, SW Japan

Yuji Ichiyama; Akira Ishiwatari; Yuka Hirahara; Kenji Shuto


Island Arc | 2006

Dredge petrology of the boninite- and adakite-bearing Hahajima Seamount of the Ogasawara (Bonin) forearc: An ophiolite or a serpentinite seamount?§

Akira Ishiwatari; Yuki Yanagida; Yibing Li; Teruaki Ishii; Satoru Haraguchi; Kazuto Koizumi; Yuji Ichiyama; Masaru Umeka


International Geology Review | 2004

Alaskan-Type Plutons and Ultramafic Lavas in Far East Russia, Northeast China, and Japan

Akira Ishiwatari; Yuji Ichiyama


Contributions to Mineralogy and Petrology | 2005

HFSE-rich picritic rocks from the Mino accretionary complex, southwestern Japan

Yuji Ichiyama; Akira Ishiwatari


Island Arc | 2004

Petrochemical evidence for off-ridge magmatism in a back-arc setting from the Yakuno ophiolite, Japan

Yuji Ichiyama; Akira Ishiwatari


Contributions to Mineralogy and Petrology | 2014

Jurassic plume-origin ophiolites in Japan: accreted fragments of oceanic plateaus

Yuji Ichiyama; Akira Ishiwatari; Jun-Ichi Kimura; Ryoko Senda; Tsuyoshi Miyamoto


Mineralogy and Petrology | 2014

Podiform chromitite formation in a low-Cr/high-Al system: An example from the Southwest Indian Ridge (SWIR)

Betchaida D. Payot; Shoji Arai; Henry J. B. Dick; Natsue Abe; Yuji Ichiyama


Island Arc | 2007

Olivine‐spinifex basalt from the Tamba Belt, southwest Japan: Evidence for Fe‐ and high field strength element‐rich ultramafic volcanism in Permian Ocean

Yuji Ichiyama; Akira Ishiwatari; Kazuto Koizumi; Yoshito Ishida; Sumiaki Machi

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Takayuki Tomiyama

Japan Agency for Marine-Earth Science and Technology

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Hiroki Horikawa

Japan Agency for Marine-Earth Science and Technology

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Jun-Ichi Kimura

Japan Agency for Marine-Earth Science and Technology

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Ryoko Senda

Japan Agency for Marine-Earth Science and Technology

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Yasunori Hanafusa

Japan Agency for Marine-Earth Science and Technology

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Yukihiko Nakano

Japan Agency for Marine-Earth Science and Technology

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