A large area of distributed granodiorite in the West TianShan of Xinjiang,containing higher Na2O+K2O,A/ CNK 0.74～0.97,is quasi alumina,Sodic,the genetic type is Ⅰ type granite;REE enrichment,the heavy REE behave as right deviation allocation model;δEu in weakly foliated porphyritic granodiorite showes moderate negative anomaly,there is no anomaly in the strong granulite granodiorite.General enrichment of trace elements with large ion affinity stone elements,loss of high field elements.Ba,Rb,K,Nb,Ta,Ti elements showed obvious loss characteristics,characterized by island arc volcanic rocks.The zircon U-Pb age is (321.9+ 1.2) Ma,which belongs to late carboniferous.Comprehensive geological observation,regional geological structure,southern Tianshan Xiang gneissic granodiorite formed in the South Tianshan ocean closure period,arc largely vanished gradually to the collision of the transition phase.%新疆西天山天山乡地区大面积分布片麻状花岗闪长岩,含较高的Na2O+K2O,A/CNK为0.74～0.97,为准铝质、钠质,成因类型为I型花岗岩,稀土元素富集、重稀土亏损的右倾型分布模式,δEu在弱片麻状似斑状花岗闪长岩中呈中等负异常,在强片麻状花岗闪长岩中基本无异常;微量元素总体富集大离子亲石元素,亏损高场强元素,Ba,Rb,K,Nb,Ta,Ti元素呈明显的亏损特征,具岛弧火山岩特征;锆石U-Pb年龄为(321.9±1.2) Ma,为早石炭世晚期.综合野外地质观察、区域地质构造,认为天山乡南部片麻状花岗闪长岩形成于南天山洋闭合时期,岛弧基本消亡逐渐向陆陆碰撞的过渡阶段.
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