阿尔泰造山带南缘富蕴后造山线形花岗岩体锆石U-Pb年龄及其地质意义

TIMS U-Pb zircon ages of Fuyun post-orogenic linear granite plutons on the southern margin of Altay orogenic belt and their implications

阿尔泰造山带南缘发育一系列后造山花岗岩体。富蕴南额尔齐斯断裂带中发育具有片麻理的黑云母花岗岩体,其中还侵入有未变形的黑云母花岗岩体。本文对这两个岩体进行了 TIMS 法锆石 U-Pb 测年,结果分别为 281±5 Ma(变形岩体)和275±2 Ma(不变形岩体),显示其为后造山花岗岩体。该研究表明,阿尔泰造山带在281± 5 Ma 时仍存在一定规模的后造山剪切作用,275±2 Ma 之后变形作用开始变弱。

A series of post-orogenic granite plutons occur on the southern margin of Altay orogenic belt. A gneissic deformed granitic pluton occurs in the Ertix faulted zone to the south of Fuyun, intruded by an underformed granitic pluton. The former pluton is dated by U-Pb TIMS method at 281 ± 5 Ma and the latter at 275 ± 2 Ma. These data indicate that shearing deformation still took place to some extent along Ertix zone during ca. 280 275 Ma in the post-orogenic period. The deformation probably ended or became much weaker after 275 ± 2 Ma.