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Comparative petrologic study of ophiolitic rocks in the Japanese Islands and Russian Far East

日本列岛和俄罗斯远东地区蛇绿岩的比较岩石学研究

基本信息

批准号：
10640462
负责人：
ISHIWATARI Akira
金额：
$ 1.79万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640462/
关键词：
ophiolite the Inner Zone of Southwest Japan Russian Far East Sikhote Alin, Primorye Omi-Renge metamorphic rocks eclogitic blueschist Tamba and North Kitakami belt accreted greenstone 夜久野オフィオライトトロクトライトロシア沿海州シホテアリン丹波帯ロシア沿海州

项目摘要

(1) Research in Japan. Western part of the Yakuno ophiolite exposed in the Kamigori area constitutes a crustal section of the late Paleozoic oceanic island arc. The coexistence of Ca-rich plagioclase and Fe-rich clinopyroxene in the metagabbro as well as highly depleted incompatible trace elements in amphibolite support this identification, which is also confirmed by the finding of shoshonitic rocks. We measured K-Ar age of hornblende from metacumulates of the Oeyama ophiolite, and confirmed their early Paleozoic age (400-440 Ma). We find eclogitic glaucophane schist from the Renge blueschist belt in the Omi area. This finding proves that the Renge metamorphism reached the eclogite facies. In the Jurassic accretionary complex of the North Kitakami belt in Aomori Prefecture, we find that the accreted volcanic rocks (greenstones) are mostly of ocean-island tholeiite origin. This clearly contrasts to the reported alkali basalt origin, which predominates greenstones in the southern Iwate Prefecture area, and proves magmatic diversity of the accreted seamounts.(2) Research in Russia. The Elistratova ophiolite in Taigonos Peninsula at the southern edge of the Koryak Mountains shows peculiar occurrence, where a stratified sequence of an island-arc ophiolite intrudes into the oceanic mantle peridotite. Extreme diversity in the degree of depletion of mantle peridotite along the eastern coast of Taigonos Peninsula is also revealed. In Primorye, we find that the Cambrian Khanka ophiolite shows distinct "passive continental margin" occurrence clearly different from the other "accretionary" early Paleozoic ophiolites in the Sikhote Alin accretionary system. Our petrologic and geochronologic study of the associated blueschist revealed close analogy between Oeyama ophiolite-Renge blueschist pair in Japan and the "accretionary" early Paleozoic ophiolite-late Paleozoic blueschist pair in Primorye.

(1)日本的研究。出露于上郡地区的八久野蛇绿岩的西部构成晚古生代洋岛弧的地壳剖面。变质辉长岩中富钙斜长石和富铁单斜辉石的共存以及角闪岩中不相容微量元素的高度亏损支持了这一鉴定，钾玄质岩石的发现也证实了这一点。本文对大山蛇绿岩变质堆积物中角闪石的K-Ar年龄进行了测定，确定了它们的早古生代年龄（400-440 Ma）。我们在近江地区的伦盖蓝片岩带中发现了榴辉蓝闪片岩。这一发现证明了仁格变质作用已达到榴辉岩相。在青森县北北上带侏罗纪增生杂岩中，发现增生火山岩（绿岩）多为洋岛拉斑玄武岩成因。这与报告的岩手县南部地区以绿岩为主的碱性玄武岩成因形成鲜明对比，证明了增生海山的岩浆多样性。(2)在俄罗斯的研究。科里亚克山南缘泰戈诺斯半岛的埃利斯特拉托娃蛇绿岩具有特殊的产状，岛弧蛇绿岩的层状序列侵入洋幔橄榄岩中。还揭示了泰戈诺斯半岛东海岸沿着地幔橄榄岩亏损程度的极端多样性。在Primorye，我们发现寒武纪Khanka蛇绿岩显示出明显的“被动大陆边缘”产状，明显不同于Sikhote Alin增生系统中的其他“增生”早古生代蛇绿岩。我们的岩石学和地质年代学研究的相关蓝片岩之间的Oeyama蛇绿岩-Renge蓝片岩对在日本和“增生”早古生代蛇绿岩-晚古生代蓝片岩对滨海边疆区之间的密切相似性。