新疆西昆仑盼水河地区晚三叠世花岗闪长斑岩LA-ICP-MS锆石U-Pb年龄和岩石地球化学特征

为进一步丰富西昆仑地区黑石北湖-三道河子一带侵入岩数据，为盼水河锑矿的形成时代提供年代学制约，对盼水河花岗闪长斑岩进行了地质学、岩石学、地球化学及年代学研究。LA-ICP-MS锆石U-Pb测年结果显示，盼水河花岗闪长斑岩年龄为210.9±2.8 Ma，形成于晚三叠世。岩石地球化学特征显示，盼水河花岗闪长斑岩SiO2含量为66.1%~72.03%，全碱（Na2O+K2O）含量为5.95%~8.29%，平均值为7.10%，K2O>Na2O，岩石富钾，显示为高钾（钙碱性）岩；岩石稀土元素总量较低，且强富集轻稀土元素，Eu具弱负异常（δEu=0.66~0.90），相对富集Rb、Th、Ta、Ce、Hf，贫化Ba、K、P、Ti。构造环境判别图解显示，盼水河花岗闪长斑岩形成于同碰撞的构造环境，揭示区内松潘-甘孜陆块西北缘在华力西晚期-印支期发生了同碰撞造山作用，区内黑石北湖-三道河子岩浆岩带正是该造山作用及洋陆转换的产物。

LA-ICP-MS zircon U-Pb age and petrogeochemical characteristics of Late Triassic granite porphyry in Panshuihe area,West Kunlum Mountains,Xinjiang

In order to further enrich the data of intrusive rocks in Heshibeihu-Sandaohezi area of West Kunlun Mountains and provide a chronologic restriction for the formation age of the Panshuihe antimony deposit, the authors studied geology, petrology, geochemistry and chronology of the granodiorite porphyry in Panshuihe.The LA-ICP-MS zircon U-Pb dating yielded the age of Panshuihe granodiorite porphyry of 210.9±2.8 Ma, suggesting Late Triassic.Rock geochemistry shows that the content of SiO2 in Panshuihe granodiorite porphyry is 66.1%~72.03%, the content of total alkali (Na2O+K2O) is 5.95%~8.29%, and the average value is 7.10%.The feature K2O > Na2O shows that the rock is rich in potassium and belongs to a high potassium (calc-alkaline) rock. The total REE is relatively low, and it shows strong enrichment of light rare earth elements, slight loss of europium (Eu=0.66~0.90), relative enrichment of Rb, Th, Ta, Ce and Hf, and relative dilution of Ba, K, P and Ti.The tectonic environment classification diagram shows that the Panshuihe granodiorite porphyry was formed in the tectonic environment of syn-collision, and that the syn-collision orogeny occurred on the northwestern margin of the Songpan-Garze landmass in this area from the Late Variscan to the Indosinian period, and the north lake of Heshibeihu-Sandaohezi magmatic belt in the area was formed by this orogenesis and the transition from ocean to land.