东昆仑巴颜喀拉浊积盆地二叠纪火山岩

东昆仑巴颜喀拉浊积盆地内沿扎拉依-哥琼尼洼断裂带及约古宗列断裂带的断夹块内出露有一套二叠纪马尔争组火山岩, 火山岩呈构造岩片形式产出, 扎拉依-哥琼尼洼断裂带火山岩岩石组合主要为玄武岩、玄武安山岩, 少量玄武岩具枕状构造, 岩石SiO₂含量均匀, TiO₂的含量较高, ALK的含量较低, 为拉斑系列的玄武岩, 玄武岩稀土总量较高, 稀土配分曲线为轻稀土富集型, 与洋岛型火山岩的稀土配分曲线相一致, 火山岩大离子亲石元素较富集, 高场强元素及重稀土元素较平坦, 稀土、微量元素特征及构造环境判别显示其形成于较富集的洋岛环境, 少数为洋中脊的构造环境.约古宗列断裂带火山岩岩石组合为玄武岩、玄武安山岩, 岩石SiO₂含量较高, TiO₂含量较低, 均 < 1%, 为钙碱性系列火山岩, 玄武安山岩的稀土配分曲线与扎拉依-哥琼尼洼断裂带一致, 而英安岩的轻稀土富集程度高, 与岛弧高钾安山岩的稀土配分曲线相吻合, 构造环境判别显示其形成于岛弧构造环境.根据扎拉依-哥琼尼洼断裂带两侧火山岩成分的差异以及断裂带两侧巴颜喀拉群碎屑物成分的差异, 可以把巴颜喀拉山三叠纪浊积盆地进一步划分为北亚带和南亚带. 

Permian Volcanic Rocks in the Bayan Hala Turbidite Basin, East Kunlun Area

Permian volcanic rocks are developed in fault nip blocks of the Zanayi-Geqiongniwa and Yueguzonglie fault zones in the Bayan Hala turbidite basin, east Kunlun area. Volcanic rocks are output in tectonic slices. The volcanic rock assemblage in the Zanayi-Geqiongniwa fault zone is mainly basalts and basaltic andesites, some with the pillow structure. The SiO_2 content of the volcanic rocks is uniform, the TiO_2 content is higher and the ALK content is lower. The rock type is mainly tholeiitic basalt. REE distribution patterns of which are LREE-rich type and consistent with those of ocean island type volcanic rocks, the large ion lithophile elements of volcanic rocks is more enrichment, HFS elements and HREE of them is flatten. The characteristics of REE, trace elements and tectonic setting distinguishing reveal that the volcanic rocks of the Zanayi-Geqiongniwa fault belt were formed mainly in an ocean island tectonic setting, while some were formed in a middle ocean ridge tectonic setting. The volcanic rock assemblage in the Yueguzonglie fault zone consists of basalt and basaltic andesite. Their SiO_2 content is higher, while TiO_2 content is less than one percent. The rock types are calc-alkaline series. REE distribution patterns of basaltic andesite are consistent with that of the volcanic rocks in the Zanayi-Geqiongniwa fault zones, that of dacite is high rich in LREE and consistent with island arc high-K andesite. Tectonic setting distinguishing reveals that the volcanic rocks of the Yueguzonglie fault belt are formed in island arc tectonic setting. According to the differing contents of the volcanic rocks and clast from the Bayan Hala Group beside the Zanayi-Geqiongniwa fault belt, we can divide the Bayan Hala turbidite basin into north subbelt and south subbelt.