东准噶尔塔合尔巴斯陶蛇绿岩带特征及地质意义

Characteristics and Geological Significance of the East JunggarTahaerbasitao Ophiolite Belt

塔合尔巴斯陶蛇绿岩位于卡拉麦里俯冲增生杂岩带的西北段,共有5个大小不同的岩片组成。地球化学显示,塔合尔巴斯陶蛇绿岩中的玄武岩具LREE轻度亏损或整体平坦特征,与MORB特征相似;辉长岩稀土元素分布模式整体显示平坦型特征,接近MORB。微量元素N-MORB标准化蛛网图显示,玄武岩、辉长岩中大离子亲石元素Sr,K,Rb,Ba明显富集,高场强元素Nb明显亏损,Ta适度富集。认为塔合尔巴斯陶蛇绿岩为卡拉麦里混杂岩带的组成部分,兼有岛弧火山岩特征,是早石炭世弧后盆地扩张的产物。

The Tahaerbasitao ophiolite is located in the northwestern section of the Kalamaili subduction accretionary mafic belt,and consists of a total of five rock fragments of different sizes.Geochemistry shows that the basalts in the Tahaerbasitao ophiolite are characterised by a mild LREE deficit or overall flatness,similar to the MORB signature;The gabbroic rare earth element partitioning pattern as a whole shows flat-type features,close to MORB.Trace element NMORB normalised spiderweb plots show that basalt and gabbro are significantly enriched in the large ionic lithophilic elements Sr,K,Rb,and Ba,while the high-field-strength element Nb is significantly deficient and Ta is moderately enriched to varying degrees.It is believed that the Tahaerbasitao ophiolite is a component of the Kalamaili mélange belt,with island arc volcanic features,and is a product of basin spreading after the Early Carboniferous arc.