Age relations and petrology of alkalic igneous rocks from Oki Dozen, Southwest Japan.
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- Morris Paul A.
- Geochemistry Section, Geological Survey of Western Australia
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- Itaya Tetsumaru
- Research Institute of Natural Sciences, Okayama University of Science
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- Iizumi Shigeru
- Department of Geoscience, Shimane University
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- Kagami Hiroo
- Institute for Study of the Earth's Interior, Okayama University
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- Watling R. John
- Chemistry Centre of Western Australia
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- Murakami Hisashi
- Cosmo Kensetsu Consultancy
書誌事項
- タイトル別名
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- Age relations and petrology of alkalic
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抄録
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.
収録刊行物
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- GEOCHEMICAL JOURNAL
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GEOCHEMICAL JOURNAL 31 (3), 135-154, 1997
一般社団法人日本地球化学会
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詳細情報 詳細情報について
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- CRID
- 1390001204550641280
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- NII論文ID
- 10008801525
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- NII書誌ID
- AA00654975
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- COI
- 1:CAS:528:DyaK2sXjvV2lu7Y%3D
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- ISSN
- 18805973
- 00167002
- http://id.crossref.org/issn/00167002
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- NDL書誌ID
- 4231174
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可