Geochronological characterization and petrogenesis of granitoids in the Ryoke belt, Southwest Japan Arc: constraints from K–Ar, Rb–Sr and Sm‐Nd systematics
Geochronological characterization and petrogenesis of granitoids in the Ryoke belt, Southwest Japan Arc: constraints from K–Ar, Rb–Sr and Sm‐Nd systematics
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日本西南弧 Ryoke 带花岗岩类的年代学特征和岩石成因：来自 K-Ar、Rb-Sr 和 Sm-Nd 系统学的约束
DOI：
10.1046/j.1440-1738.2000.00262.x
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发表时间：
2000
期刊：
影响因子：
1.5
通讯作者：
K. Nagao
中科院分区：
文献类型：
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作者：
M. Yuhara;H. Kagami;K. Nagao
对日本西南部稻田、Awaji岛和东三木地区的花岗岩和变质岩进行了Rb-Sr和K-Ar年代学研究，以探讨Ryoke带花岗岩类的侵位时代。在120 Ma至70 Ma之间，在Ina地区发生了“较年轻”的Ryoke花岗岩浆侵入，最年轻的花岗岩体侵位后立即开始冷却。Awaji岛的火成活动始于100 Ma，一直持续到75 Ma。Rb-Sr全岩等时线年龄沿弧线的变化表明，梁克带和三代带的岩浆活动几乎同时开始(约120 Ma)。最后一次岩浆作用发生在两条带的东部。花岗岩类向东年轻的Rb-Sr和K-Ar矿物年龄。年龄数据表明，Ryoke带是在火成岩活动结束后刚刚抬升的。Ryoke花岗岩类的初始锶、钕同位素比值表明，它们大多来自下地壳和/或上地幔产生的岩浆，具有统一的锶、钕同位素组成。然而，一些花岗岩类显示出Ryoke变质岩或Ryoke带下更古老的前寒武纪地壳岩石同化的证据。
Abstract Rb–Sr and K–Ar chronological studies were carried out on granitic and metamorphic rocks in the Ina, Awaji Island and eastern Sanuki districts, Southwest Japan to investigate the timing of intrusion of the granitoids in the Ryoke belt. Intrusions of ‘younger’ Ryoke granitic magmas took place in the Ina district between 120 Ma and 70 Ma, and cooling began immediately after the emplacement of the youngest granitic bodies. Igneous activity in Awaji Island was initiated at 100 Ma and continued to 75 Ma. Along‐arc variations of Rb–Sr whole‐rock isochron ages suggest that magmatism began everywhere in the Ryoke and San‐yo belts at almost the same time (ca 120 Ma). The last magmatism took place in the eastern part of both belts. Rb–Sr and K–Ar mineral ages for the granitoids young eastwards. The age data suggest that the Ryoke belt was uplifted just after the termination of igneous activity. Initial Sr and Nd isotopic ratios for the Ryoke granitoids indicate that most were derived from magmas produced in the lower crust and/or upper mantle with uniform Sr and Nd isotopic compositions. Several granitoids, however, exhibit evidence of assimilation of Ryoke metamorphic rocks or older Precambrian crustal rocks beneath the Ryoke belt.
影响因子：
3.5
作者：
H. Kagami;S. Iizumi;Y. Tainosho;M. Owada
通讯作者：
H. Kagami;S. Iizumi;Y. Tainosho;M. Owada
Yoshihiro SAWADA：“日本西南部山阴省白垩纪到新近纪火成岩的SrNd同位素系统学——岩石圈的重建——”。
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