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

摘要

The mafic rock in the Taerjiebai-Kebukete-Kuwei area of the Altay Orogenic Belt in Xinjiang,output Taerjie-bai Cu-Ni ore deposit and Kuwei V-Ti-Fe ore deposit.Through systematical investigation and analysis,a detailed petrolo-gy and geochemistry research was carried out and two rock series with different metallogenetic specialization in study ar-ea have been identified.①Rock series related to V-Ti-Fe mineralization with rock association of gabbro and diorite,short-ly called as“Ti-Fe rock series”.This series is characterized by basic,alkali,Fe,Ti,Al,Ca-rich,but low mafic index (m/f),ob-viously positive Eu anomaly,Ba,K,Sr-rich and lower Ce in chemical composition②Rock series related to Cu-Ni mineral-ization with rock association of pyroxene peridotite-Olivine pyroxenolite-pyroxenite-allalinite,shortly called as“Cu-Ni rock series”.This serie is characterized by ultrabasic,Mg-rich,and relatively lower Fe,Ti,Al,Si,K and Na,feeblish posi-tive or negative Eu anomaly,Rb,Ba,Th,K,Sr- poor and Ce- rich in chemical composition.Zircon La-ICP-MS U-Pb age of 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 them are formed in continental margin arc environment.The magma is mainly from the depleted-mantle.%新疆阿尔泰造山带塔尔结拜-科布克特-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-橄榄辉石岩-辉石岩-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。