Sr isotopic study of Ibara dismembered ophiolite from the Maizuru Tectonic Belt, Southwest Japan
Sr isotopic study of Ibara dismembered ophiolite from the Maizuru Tectonic Belt, Southwest Japan
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日本西南部舞鹤构造带伊原肢解蛇绿岩的锶同位素研究
DOI：
10.2465/ganko1941.82.1
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
H. Kagami
中科院分区：
文献类型：
--
作者：
Yoshiyuki Koide;K. Tazaki;H. Kagami
出露于麦祖鲁构造带西段的Ibara裂解蛇绿岩，主要由变质玄武岩和变质辉长岩组成。蛇绿岩的Rb-Sr全岩等时线年龄为281±8 Ma，属岩浆型，其初始锶同位素比值为0,70359±04，略高于现代摩尔玄武岩和边缘海玄武岩。较高的初始锶同位素比值可能是边缘海地幔先前被具有较高锶同位素比值的俯冲成分混染的结果。岩浆年龄与变质年龄(270~290 Ma)基本一致，表明茨原蛇绿岩是在岩浆固化后不久发生变质作用的。
Ibara dismembered ophiolite exposed in the western extension of the Maizuru Tectonic Belt is composed mainly of metabasalt and metagabbro. The Rb-Sr whole rock isochron of the ophiolite gives an age of 281±8 Ma which shows a magmatic one, and the initial Sr isotopic ratio is 0, 70359±04 which is slightly higher than those of modern MORE and marginal sea basalt. The high initial Sr isotopic ratio may result from the derivation of the marginal sea mantle previously contaminated by the subduction components having high Sr isotopic ratio. The magmatic age is almost identical with the metamorphic age (270-290Ma), This suggests that the Ibara ophiolite was metamorphosed soon after solidification of the magma.