新疆阿尔泰造山带塔尔结拜-科布克特-库卫铜镍钛铁矿区镁铁质侵入岩LA-MC-ICP-MS锆石U-Pb年龄及地球化学特征

LA-MC-ICP-MS Zircon U-Pb Geochronology and Geochemical Study of Mafic Rock at Taerjiebai-Kebukete-Kuwei Cu-Ni-Ti-Fe ore district in Altay Orogenic Belt,Xinjiang

新疆阿尔泰造山带塔尔结拜一科布克特一库卫镁铁质岩中产有塔尔结拜铜镍矿和库卫低品位钒钛磁铁矿床。经研究分析识别出两个具不同成矿专属性的岩石系列:①与钒钛磁铁矿化有关的钛铁系列。矿化岩石主要为中细粒辉长岩,次为闪长岩,岩石相对偏基性,以富碱、富铁、高钛、铝、钙而镁铁指数(m/f)低为特征,具明显正铕异常,强不相容元素Rb,Ba,K和中等不相容元素Sr总体富集,Ce相对亏损;②与铜镍硫化物矿化有关的铜镍系列。岩石组合为辉石橄榄岩一橄榄辉石岩一辉石岩一蚀变辉长岩,偏超基性,富镁,贫钛、铁,相对低铝、硅和钾、钠,具弱正铕异常或负铕异常,强不相容元素Rb,Ba,Th,K和中等不相容元素Sr总体亏损,Ce相对富集。铜镍系列岩石锆石U-Pb加权平均年龄(406.8±1.0)Ma,钛铁系列科布克特岩体锆石U-Pb加权平均年龄(407.8±1.2)Ma,二者形成于陆缘弧环境,岩浆来源亏损地幔。

The mafic rock in the Taerjiebai-Kebukete-Kuwei area of the Altay Orogenic Belt in Xinjiang,output TaerjiebaiCu-Ni ore deposit and Kuwei V-Ti-Fe ore deposit.Through systematical investigation and analysis,a detailed petrologyand geochemistry research was carried out and two rock series with different metallogenetic specialization in study areahave been identified.①Rock series related to V-Ti-Fe mineralization with rock association of gabbro and diorite,shortlycalled as“Ti-Fe rock series”.This series is characterized by basic,alkali,Fe,Ti,Al,Ca-rich,but low mafic index （m/f）,obviouslypositive Eu anomaly,Ba,K,Sr-rich and lower Ce in chemical composition②Rock series related to Cu-Ni mineralizationwith rock association of pyroxene peridotite-Olivine pyroxenolite-pyroxenite-allalinite,shortly called as“Cu-Nirock series”.This serie is characterized by ultrabasic,Mg-rich,and relatively lower Fe,Ti,Al,Si,K and Na,feeblish positiveor negative Eu anomaly,Rb,Ba,Th,K,Sr- poor and Ce- rich in chemical composition.Zircon La-ICP-MS U-Pb ageof Cu-Ni rock series is （406.8±1.0） Ma,Zircon La-ICP-MS U-Pb age of Ti-Fe rock series is （407.8±1.2） Ma,both of themare formed in continental margin arc environment.The magma is mainly from the depleted-mantle.