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Sr・Nd isotopic study on basaltic rocks from the Chubu District

中部地区玄武岩的 Sr·Nd 同位素研究

基本信息

批准号：
02640625
负责人：
UJIKE Osamu
金额：
$ 1.22万
依托单位：
Toyama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02640625/
关键词：
Strontium Isotope Neodymium Isotope Chubu District Ueno Basaltic Rocks On-take Volcano Ryohaku Mountains Mt. Kunimi-dake Tojimbo 玄武岩同位体組成マグママントル

项目摘要

(1) The Ueno and On-take basaltic rocksTen samples of the Ueno basaltic rocks (2.7-0.9 Ma) have ^<87>Sr/ ^<86>Sr-0.7055-0.7070 and epsilon _<nd>-+3.3-1.1, and show no specific secular variation in isotpic compositions. The Ueno samples are higher in ^<87>Sr/ ^<86>Sr than basaltic rocks from the On-take volcano (<0.8 Ma) which lie within the mantle array on an epsilon _<nd>-^<87>Sr/ ^<86>Sr diagram. Because (1) the Ueno and On-take basaltic rocks were formed in the same area and (2) the difference in their ^<87>Sr/ ^<86>Sr cannot be ascribed to possible contamination by the crust, some episode (arrival of the leading edge of the subducting Philippine Sea plate?) seems to have occurred at 1+alpha Ma in the upper-mantle beneath central Japan.(2) The Jizo-toge andesitic rocksThe Jizotoge andesitic rocks, formed at -2 Ma nearby the Ueno basaltic rocks, bear epsilon _<nd>-^<87>Sr/ ^<86>Sr relations similar to that of the Ueno basaltic rocks. The epsilon _<nd> and ^<87>Sr/ ^<86>Sr compositions of magmas generated at -2 Ma in this area seem to be insignificantly affected by the crustal material.(3) Volcanic rocks from the Ryohaku Mountains and Fukui PrefectureThe epsilon _<nd>-^<87>Sr/ ^<86>Sr relations of volcanic rocks from the Ryohaku Mountains (Mts. Gankyoji-yama, Dainichiga-take, Kyoga-take and Bishamon-dake) and Fukui Prefecture (Mt. Kunimi-dake and Tojimbo) are largely similar to that of the Ueno basaltic rocks, but they show a greater scatter trending towards a higher ^<87>Sr/ ^<86>Sr and lower epsilon _<nd> direction.

(1)上野玄武岩和上山玄武岩：10个上野玄武岩样品(2.7~0.9 Ma)具有^&lt；87&gt；sr/^&lt；86&gt；sr-0.7055-0.7070和epsilon_&lt；nd&gt；-3.3-1.1，同位素组成没有明显的长期变化。Ueno样品的^&lt；87&gt；sr/^&lt；86&gt；sr；由于(1)上野玄武岩和接壤玄武岩形成于同一地区，以及(2)它们的差异不能归因于地壳可能的混染，某些事件(俯冲菲律宾海板块前缘的到达？)(2)吉佐托格安山岩。吉佐托格安山岩形成于-2 Ma，形成于上野玄武岩附近，具有与上野玄武岩相似的Esisilon&lt；Nd&gt；-^&lt；87&gt；sr/^&lt；86&gt；本区-2 Ma岩浆的epsilon&lt；nd&gt；和^&lt；87&gt；sr/^&lt；86&gt；sr组分似乎不受地壳物质的影响。(3)琉球山脉和福井县的火山岩。Gankyoji-yama、Dainichiga-Take、Kyoga-Take和Bishamon-Dake)和福井县(Mt.Kurimi-dake和Tojimbo)与上野玄武岩基本相似，但它们具有较大的分散性，倾向于较高的^&lt；87&gt；sr/^&lt；86&gt；sr和较低的epsilon；