Genesis of jadeite–quartz rocks in the Yorii area of the Kanto Mountains, Japan

Fukuyama, Mayuko; Ogasawara, M.; Horie, Kenji; Lee, Der-Chuen

doi:10.1016/j.jseaes.2012.10.031

Cited by 24 publications

(29 citation statements)

References 50 publications

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“…The jadeite-quartz rocks are exposed as an isolated block, typically 10 × 5 m in size, in 20 × 10 m area at the top of a small hill, and have no direct relationship to other units (Hirajima, 1983;Fukuyama et al 2013). The jadeite-quartz rocks are thought to be enclosed in the surrounding serpentinite mélange, because serpentinite boulders are present near the jadeite-quartz rocks.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…The jadeite-quartz rocks record a jadeite + quartz = albite reaction . Details of descriptions of jadeite-quartz rocks including mineral compositions are shown in Fukuyama et al (2013). Mineral abbreviations here and throughout the paper are after Whitney and Evans (2010).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…Whole-rock trace element compositions of jadeite-quartz rock samples, which were previously examined for major and some trace elements with XRF in Fukuyama et al (2013), were determined by 7700x Quadrupole-ICP-MS (Agilent, U.S.A.) at Akita University. Calibration standards with 10 ng/g and 100 ng/g were prepared in 0.5M HNO 3 from multi-element standard solution, ICP-MS-68A and ICP-MS-68B (High Purity Standards, U.S.A.), respectively.…”

Section: Whole-rock Trace Element Analysesmentioning

confidence: 99%

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Chemical composition of fluid inclusions in the Yorii jadeite–quartz rocks from the Kanto Mountains, Japan

Fukuyama

Kawamoto

Ogasawara

2017

Journal of Mineralogical and Petrological Sciences

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Jadeite-quartz rocks from the Yorii area, the Kanto Mountains, central Japan occur as tectonic blocks within serpentinite mélange. Primary two-phase (liquid + vapor) aqueous fluid inclusions are observed in jadeite, quartz, albite and zircon. The fluids trapped in jadeite and quartz are H 2 O with and without CH 4 and show a wide range of salinity (4.7 ± 1.1 wt% NaCl eqv in jadeite; 3.4 ± 0.7 and 13.6 ± 2.0 wt% NaCl eqv in quartz). In this study, we examined the chemical composition of fluid inclusions in quartz from jadeite-quartz rock to understand the characteristics of fluid, which related to the formation of the rocks in the subduction zone. The trace element concentrations of fluid inclusions determined with LA-ICP-MS are enriched in LILE, Li, B, HFSE and transition metals with LILE enriched and relatively HFSE depleted characteristics. These have elemental patterns similar to the HFSE-depleted fluid released from antigorite during subduction, though the orders of magnitude are different. It can be common chemical characteristics of fluid in a subduction zone. There are two possibilities of the chemical composition of the evolved fluid after the formation of jadeite-quartz rocks. HFSE from the fluid can be sequestered into jadeite-quartz rock prior to fluids moving up into a mantle wedge. This process lead the evolved fluids relatively depleted in HFSE and enriched in LILE. Other possibility is that the fluid has same chemical composition of fluid inclusion as the fluid is equilibrated with jadeite-quartz rocks during the jadeite-quartz formation. In both cases, fluid after the metasomatic formation of jadeite-quartz rocks can be relatively enriched in LILE and depleted in HFSE. Magmas generated in subduction zones exhibit distinctive geochemical features of LILE enrichment and HFSE depletion and this characteristic of arc magma can be explained by the behavior of HFSE during the formation of jadeite-quartz rocks.

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Section: Geological Backgroundmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Whole-rock Trace Element Analysesmentioning

confidence: 99%

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Chemical composition of fluid inclusions in the Yorii jadeite–quartz rocks from the Kanto Mountains, Japan

Fukuyama

Kawamoto

Ogasawara

2017

Journal of Mineralogical and Petrological Sciences

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“…Hirajima (1984) considered Yorii jadeite-bearing rocks to be members of the Kurosegawa belt. Fukuyama et al (2013) reported U-Pb zircon ages of 162.2 ± 0.6 Ma from the Yorii samples, which are distinctly older than the Late Cretaceous Sanbagawa metamorphism (about 80-95 Ma U-Pb detrital zircon ages: Tsutsumi et al, 2009). The K-Ar phengite ages of metapelite from the Sanbagawa metamorphic belt yield about 58-84 Ma, which is comparable to the U-Pb detrital zircon ages (Hirajima et al, 1992;Miyashita and Itaya, 2002).…”

Section: Introductionmentioning

confidence: 97%

Coexistence of jadeite and quartz in garnet of the Sanbagawa metapelite from the Asemi–gawa region, central Shikoku, Japan

Taguchi

Enami

2014

Journal of Mineralogical and Petrological Sciences

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Coexistence of jadeite (Jd 92 ) and quartz was newly found in an inner segment of a composite-zoned garnet from a metapelite in the southern albite-biotite zone of the Asemi-gawa region, Sanbagawa belt in central Shikoku, Japan. The assemblage of jadeite + quartz in garnet gives a minimum metamorphic pressure of 1.4-1.9 GPa at 500-700°C, which was significantly higher than that previously proposed for epidote-amphibolite facies conditions in the albite-biotite zone. Garnet includes quartz retaining high residual pressure (Δω 1 values up to 11.7 cm −1 ), which is comparable to the residual pressure reported in eclogite and metapelite within the eclogite unit in central Shikoku. These results imply that (1) the inner segment of the composite-zoned garnet records prograde recrystallization under high-pressure blueschist to eclogite facies conditions and (2) at least a part of the southern albite-biotite zone of the Asemi-gawa region recrystallized under higher pressure conditions prior to the regional metamorphism from the greenschist to epidote-amphibolite facies that formed the regional thermal structure of the Sanbagawa belt of central Shikoku.

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“…Hirajima (1983) reported jadeitequartz rock from a serpentinite mélange in the Yorii area of the Kanto Mountains. Fukuyama et al (2013) showed jadeite crystallization in the Yorii tectonic blocks took place at 162.2 ± 0.6 Ma based on zircon U-Pb ages. Although this age is significantly younger than the other jadeite-bearing tectonic blocks in the Kurosegawa zone, the Jurassic age and high-P conditions in the jadeite + quartz stability field suggest the jadeite-forming metamorphism is unrelated to the Sanbagawa metamorphism.…”

Section: Introductionmentioning

confidence: 98%

Jadeite–bearing metaigneous rocks from the Northern Chichibu belt, SW Japan: implications for the lowest–grade Sanbagawa metamorphism

Endo

2015

Journal of Mineralogical and Petrological Sciences

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Multiple generations of Na-Ca and Na pyroxenes (aegirine-augite, aegirine and jadeite) were found in a metamorphosed monzonitic dike from a coherent mafic layer of the Northern Chichibu belt in central Shikoku, Japan. The mafic layer was derived from alkaline basalt magma and its derivatives, and belongs to the Kamiyoshida unit (Middle Jurassic accretionary complex). The earliest-stage sodic pyroxene (jadeite-free Ti-rich aegirine-augite to aegirine) in the dike probably crystallized during a post-magmatic hydrothermal stage. Igneous Ti-rich augite phenocrysts were almost completely pseudomorphed by chlorite + phengite + Al-OH-rich titanite + sodic pyroxene (aegirine-augite with jadeite component) during early stages of subduction metamorphism. The earliest-stage sodic pyroxene and pseudomorphed Ti-rich augite were further overgrown by jadeite/ aegirine fringes during high-P/T metamorphism. Jadeite/aegirine pyroxene also occurs as small (~50 µm long) neoblasts within pseudomorphs (albite + phengite + pumpellyite ± Ba-rich K-feldspar) after igneous plagioclase. Individual grains of the fringe/neoblastic pyroxene are zoned with a jadeite core (up to 98% jadeite content) and an aegirine rim (down to 25% jadeite content). Jadeite-rich pyroxene (up to 92% jadeite content) was also found in basaltic rock from the mafic layer. The absence of quartz and the alkaline affinity of the protoliths suggest that the jadeite formation can be explained by the reaction analcime = jadeite + H 2 O. If H 2 O fluid was present, the decrease in jadeite content in the fringe/neoblastic pyroxene implies decompression from 0.6-0.7 GPa at 300°C to~0.4 GPa at 210-260°C. The formation of the jadeite-to-aegirine pyroxene during exhumation probably resulted from the lowest-grade Sanbagawa metamorphism.

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Genesis of jadeite–quartz rocks in the Yorii area of the Kanto Mountains, Japan

Cited by 24 publications

References 50 publications

Chemical composition of fluid inclusions in the Yorii jadeite–quartz rocks from the Kanto Mountains, Japan

Chemical composition of fluid inclusions in the Yorii jadeite–quartz rocks from the Kanto Mountains, Japan

Coexistence of jadeite and quartz in garnet of the Sanbagawa metapelite from the Asemi–gawa region, central Shikoku, Japan

Jadeite–bearing metaigneous rocks from the Northern Chichibu belt, SW Japan: implications for the lowest–grade Sanbagawa metamorphism

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