Enriched mid–ocean ridge basalt–type geochemistry of basalts and gabbros from the Nikoro Group, Tokoro Belt, Hokkaido, Japan

Yamasaki, Toru; Nanayama, Futoshi

doi:10.2465/jmps.170613

Cited by 13 publications

(16 citation statements)

References 21 publications

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“…As a kind of intrusive rock, gabbroic rocks exist in two forms: (1) cumulate gabbroic rocks that have a layered structure and (2) homogeneous gabbroic rocks that are composed of pyroxene and plagioclase, which result from residual magma. The compositions of cumulate gabbroic rocks are significantly different from those of basalts, while the compositions of homogeneous gabbroic rocks are generally similar to those of basalts [16,17]. As a gabbroic rock can be mainly composed of either cumulate rocks or residual magma, the compositions of gabbroic rocks are complex.…”

Section: Using Gabbroic Rocks In Discrimination Tasks?mentioning

confidence: 96%

“…Gabbro, a basic intrusive rock, is widespread in the Earth's crust. The chemical composition of gabbroic rocks (except for cumulate gabbros) are similar to those of basalts [16][17][18]. However, the petrogenesis of gabbroic rocks is more complicated than that of basalts, and the existing discrimination diagrams for basalts cannot be applied to discriminate among the different tectonic settings of gabbroic rocks.…”

Section: Introductionmentioning

confidence: 99%

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An Automated Method to Generate and Evaluate Geochemical Tectonic Discrimination Diagrams Based on Topological Theory

Han

Zhang

et al. 2020

Minerals

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Discrimination diagrams can be used to distinguish different tectonic settings of igneous rocks. To improve the quality and efficiency of the design of discrimination diagrams, an automatic design and assessment method for discrimination diagrams is proposed based on topology theory. The method is aimed at programming the traditional process of discrimination diagram design, enabling computers to simulate the visual discrimination process. It thus automatically designs tectonic setting discrimination diagrams by investigating all possible combinations of geochemical elements. In the experiment, analyses of 3803 gabbro samples were collected from three tectonic settings, including island arc, ocean island, and mid-oceanic ridge. Using the proposed method, we found thousands of discrimination diagrams with fields overlapping less than 10%. By analyzing these diagrams, the most critical elements (or element ratio pairs) are identified. Based on the result, the feasibility of using gabbroic rocks to discriminate between tectonic settings is illustrated and four representative discrimination diagrams, including the La/Y–Nb/Ba diagram, Nb/Sc–Sc/Ba diagram, Ba/Nb–Ba/Sc diagram, and La/Na2O–Nb/Ba diagram, are recommended for use. This research supports the view that gabbroic rocks can also be used to discriminate between different tectonic settings. The method could also be applied to other rock types.

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Section: Using Gabbroic Rocks In Discrimination Tasks?mentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

An Automated Method to Generate and Evaluate Geochemical Tectonic Discrimination Diagrams Based on Topological Theory

Han

Zhang

et al. 2020

Minerals

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“…The pelagic sediments yield Late Jurassic to Early Cretaceous micro fossils (Iwata et al, 1990;Kiminami, Suizu, & Kontani, 1983;Okada et al, 1989) and the clastic deposits are likely to be Upper Cretaceous (Sakakibara, Isozaki, Nanayama, & Narui, 1993). The mafic rocks of the Nikoro Group show a mixture of tholeiitic and alkaline basaltic compositions, which may represent abyssal ocean floor and seamount origins, respectively (Niida, 1981;Sakakibara et al, 1986), or ocean floor affected by plume-ridge interaction (Yamasaki & Nanayama, 2017). Zeolite to prehnite-pumpellyite facies metamorphism is widespread and associated with the development of metamorphic aragonite, lawsonite, sodic pyroxene, and sodic amphibole.…”

Section: Tokoro Terrane (Tk)mentioning

confidence: 99%

The basement geology of Japan from A to Z

et al. 2020

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The Precambrian and lower Paleozoic units of the Japanese basement such as the Hida Oki and South Kitakami terranes have geological affinities with the eastern Asia continent and particularly strong correlation with units of the South China block. There are also indications from units such as the Hitachi metamorphics of the Abukuma terrane and blocks in the Maizuru terrane that some material may have been derived from the North China block. In addition to magmatism, the Japanese region has seen substantial growth due to tectonic accretion. The accreted units dominantly consist of mudstone and sandstone derived from the continental margin with lesser amounts of basaltic rocks associated with siliceous deep ocean sediments and local limestone. Two main phases of accretionary activity and related metamorphism are recorded in the Jurassic Mino-Tanba-Ashio, Chichibu, and North Kitakami terranes and in the Cretaceous to Neogene Shimanto and Sanbagawa terranes. Other accreted material includes ophiolitic sequences, e.g. the Yakuno ophiolite of the Maizuru terrane, the Oeyama ophiolite of the Sangun terrane, and the Hayachine-Miyamori ophiolite of the South Kitakami terrane, and limestone-capped ocean plateaus such as the Akiyoshi terrane. The ophiolitic units are likely derived from arc and back-arc basin settings. There has been no continental collision in Japan, meaning the oceanic subduction record is more complete than in convergent orogens seen in intracontinental settings making this a good place to study the geological record of accretion. Hokkaido lacks most of the Paleozoic history recognized in Honshu, Shikoku, Kyushu, and the Ryukyu Islands to the south and its geology reflects the Cenozoic development of two convergent domains with volcanic arcs, their approach, and eventual collision. The Hidaka terrane reveals a cross section through a volcanic arc and the main accretionary complex of the convergent system is represented by the Sorachi-Yezo terrane.

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“…Amphibolites in the Hidaka Metamorphic Belt (Mikoshiba, 1999) Amphibolites in the Hidaka Metamorphic Belt (Kawanami et al, 2006) Amphibolites in the Okutokachi area (Kawanami et al, 2006) Greenstones in the Shimokawa area (Kawanami et al, 2006) Meguro Andesitic Dikes (Furukata et al, 2010) Rekifune Volcanic Rocks (Furukata et al, 2010) Volcanic rocks in the Toyokoro area (Furukata et al, 2010) Rekifune Volcanic Rocks (Yamagishi et al, 1989) Greenstone in the Nikoro Group (Yamasaki and Nanayama, 2017) Daimaruyama Greenstones…”

mentioning

confidence: 99%

“…Amphibolite in the Hidaka Metamorphic Belt fromMikoshiba (1999) andKawanami et al (2006) in panel (b) are averaged values for N = 12 and N = 11, respectively. Data for the Nikoro Group in the panel (d) is averaged values for N = 11(Yamasaki and Nanayama, 2017). Normalization values for CI chondrite and N-MORB, and element orders are fromSun and McDonough (1989).…”

mentioning

confidence: 99%

Whole-rock geochemical compositions of igneous-origin rocks from the 1:200,000, Hiroo Quadrangle and related area.

Yamasaki

Nanayama

Takahashi

et al. 2018

Bull. Geol. Surv. Japan

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Whole-rock major and trace geochemical analyses of igneous rocks and igneous-origin rocks from the 1:200,000, Hiroo Quadrangle and related area have been carried out to confirm geotectonic attribution and correlation. Studied samples are; 1) Okutokachi Amphibolite, 2) Rekifune Volcanic Rocks, 3) dolerite dike in the Okawa Formation (Middle Miocene), 4) greenstone in the Toyokoro area (originated from Nikoro Group, Tokoro Belt), 5) granitic gravels in the Toyonigawa Formation (Middle-Late Miocene), 6) Nupinai Granite in the Hidaka Metamorphic Belt, 7) mafic volcanic gravels in the Nakanogawa Group, Hidaka Belt (Paleocene-Eocene), 8) greenstone from the Daimaruyama Greenstone body in the Nakanogawa Group, 9) granitic gravel in the Erimo Formation (Utaro Conglomerate: Late Oligocene), and 10) acidic tuff in the Sakashita Formation, Nakanogawa Group, Hidaka Belt. Obtained data are important as the scientific bases of the 1:200,000, Hiroo Quadrangle (2nd edition), and valuable information for future researches. Based on the analytical results, geotectonic attribution, origin and tectonics of the studied samples are preliminary discussed.

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Enriched mid–ocean ridge basalt–type geochemistry of basalts and gabbros from the Nikoro Group, Tokoro Belt, Hokkaido, Japan

Cited by 13 publications

References 21 publications

An Automated Method to Generate and Evaluate Geochemical Tectonic Discrimination Diagrams Based on Topological Theory

An Automated Method to Generate and Evaluate Geochemical Tectonic Discrimination Diagrams Based on Topological Theory

The basement geology of Japan from A to Z

Whole-rock geochemical compositions of igneous-origin rocks from the 1:200,000, Hiroo Quadrangle and related area.

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