SHRIMP dating of the Qiqijianake ophiolitic mélange in the Kokshai region, southwestern Tianshan and its tectonic implications
南天山齐齐加纳克蛇绿混杂岩的SHRIMP年龄及其构造意义

Qiqijianake ophiolitic mélange is located in the kokshal region in southwestern Tianshan of Xinjiang, China. It mainly consists of pyroxene peridotite, olivine pyroxenite, olivine basalt, gabbro, diabase, basaltic lavas, which is exposed as a series of tectonic blocks with the length of 5km and width of 500m. In this paper, we report the SHRIMP U-Pb zircon data for basalt from the Qiqijianake ophiolitic mélange in studied area. It shows that the Qiqijianake ophiolitic mélange formed in the Early Devonian (399±4Ma). In combination with previously published data, we infer that the Qiqijianake ophiolitic mélange and Jigen ophiolitic remnant are the extention of South Tianshan ophiolite zone in Central Asia, which may be the product of a narrow archipelagic ocean. It represents the suture of the northward subduction of South Tianshan Ocean and collision between the Tarim Plate and Kazakhstan-Junggar Plate occurred after the subduction.