THE U-PB GEOCHRONOLOGY AND GEOCHEMICAL CHARACTERISTICS OF THE SAERGAN MAFIC ROCKS IN THE KEPING AREA, SOUTHWEST TIANSHAN, CHINA
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摘要: 柯坪地区发育一套沿走滑断层侵位的萨尔干基性岩脉,其产出于西南天山造山带与塔里木克拉通的接触部位,具有重要的意义。文章通过对萨尔干基性岩脉样品进行锆石LA-ICP-MS U-Pb年代学、岩石地球化学分析,探讨西南天山中新生代陆内造山作用过程。结果表明,萨尔干基性岩脉的LA-ICP-MS锆石U-Pb年龄为(49.14±0.8)Ma,表明该套岩石形成于始新世。地球化学表明该套岩石形成于与青藏高原碰撞远程效应相关的构造背景。Abstract: There is a set of mafic rocks developed along the Saergan strike-slip faults in the Keping area, which is of great significance to understanding the internal relations between the southwest Tianshan orogenic belt and the Tarim Craton. The zircon U-Pb geochronology and geochemical analysis of the Saergan Mafic rocks are used to investigate the effect of the Cenozoic intracontinental orogeny process of the Southwest Tianshan orogenic belt. The zircon LA-ICP-MS U-Pb age of the Saergan mafic rock is 49.14±0.8 Ma, indicating that the mafic rocks were formed in Eocene. Geochemistry data shows that the rocks have an important relationship with the remote effects of the collision between the Indian plate and the Eurasian plate.
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Key words:
- southwest Tianshan /
- Keping /
- U-Pb chronology /
- Saergan area /
- mafic rocks
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图 1 西南天山造山带地质图
1—新生代地层;2—中生代地层;3—古生代地层;4—前寒武纪地层;5—蛇绿混杂岩;6—超基性-基性侵入岩;7—花岗岩;8—湖泊;9—冰川;10—断层;
①—扎拉依尔—奈曼缝合带;②—尼古拉耶夫线—那拉提北缝合带;③—南中天山缝合带;④—塔里木北缘断裂带; ⑤—塔拉斯—费尔干纳走滑断裂带;
KNTS—吉尔吉斯斯坦北天山;YB—伊犁地块;TB—塔里木陆块;CTA—中天山复合弧地体;STOB—西南天山造山带a—中亚造山带构造简图;b—西南天山及其邻区地质图[1-3]Figure 1. Tectonic sketch map of the southwest Tianshan orogen
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