东准噶尔地区扎河坝-阿尔曼太蛇绿岩多期次岩浆演化特征：来自锆石U—Pb年代学的证据

Multistage evolution of Zhaheba-Aermantai ophiolite in eastern Junngar： Evidence from zircon

新疆东准噶尔地区阿尔曼太蛇绿岩被认为是早古生代大洋岩石圈残片，其主要由地幔橄榄岩、辉长岩、玄武岩以及硅质岩组成。通过野外地质观测，发现在扎河坝—阿尔曼太蛇绿岩内侵入了大量的岩体，主要为闪长岩以及闪长玢岩。本文通过LA-ICP-MS 锆石U-Pb 定年，获得蛇绿岩中辉长岩年龄为497.3 ± 4.5 Ma，而后期侵入的闪长玢岩的年龄为424.5 ± 3.1 Ma。前人研究认为这些闪长玢岩具有岛弧岩浆岩特征。结合区域地质背景，本文认为这些后期侵入的闪长玢岩是岛弧岩浆作用的结果， 推测阿尔曼太蛇绿岩为一个岛弧多期次演化的产物。

The Zhaheba-Aermantai ophiolite of eastern Junggar, Xinjiang Province, is considerate as Early Paleozoic fossil oceanic lithospheric slab. It is composed of mantle peridotite, gabbro, basalt and chert. Based on the field investigation, the Zhaheba-Aermantai ophiolite is intruded by late magmatic rocks such as diorite porphyry. According to the LA-ICP-MS dating, U-Pb zircon age of gabbro is 497.3 ± 4.5 Ma and the age of intruding diorite porphyry is 424.5 ± 3.1 Ma. These diorite porphyry are indicated that they are of island arc geochemistry affinity. Combined with regional geology of Zhaheba-Aermantai area, the later intrusion of diorite porphyry are magmatism of island arc evolution followed ophiolite formation. It gives light on the multistage evolution of ophiolite origin in Zhaheba-Aermantai area.