新疆卡特巴阿苏金矿床含矿岩石及围岩地球化学特征与构造环境简析

The Geochemical Characteristics and Tectonic Environment Analysis of Ore-bearing Rock and Wall Rock in Katebaasu gold deposit,Xinjiang

卡特巴阿苏金矿床位于新疆西天山那拉提山中段,矿区侵入岩发育,主要含矿岩石为二长花岗岩,花岗闪长岩次之,围岩以碱长花岗岩为主,少量闪长岩。通过锆石SHRIMP U-Pb测年得出二长花岗岩侵位年龄为(345.5±2.6)Ma^(356.8±5.2)Ma,为晚泥盆世末期—早石炭世岩浆活动产物。经岩石化学分析,SiO_2含量47.77%~77.11%,Al_2O_3含量12.31%~16.91%,里特曼指数(σ)均值3.82,A/NCK(铝系数)均值0.98,为次铝质中高钾钙碱性系列岩石。稀土元素具轻稀土元素富集、重稀土元素亏损特点,(La/Yb)_N平均8.81,δEu平均0.68,显示Eu弱负异常。微量元素标准化蛛网图上显示Nb,Ta,P,Ti亏损,Rb,Th,K相对富集。通过岩石主量、微量和稀土元素特征、岩石化学图解及地质背景分析,认为矿区含矿岩石及围岩属中高钾钙碱性系列的岛弧"Ⅰ"型花岗岩,具以壳源为主的壳幔混合源成因特点,构造环境为活动大陆边缘的火山弧环境,与板块俯冲作用相关。

The gold deposit of Katebaasu located in the middle of Nalati mountain,west tianshan in Xinjiang,mine and surrounding intrusive rocks,the main ore-bearing rocks are adamellite, granodiorite take second place,wall rock are mainly alkali-feldspar granite,and a small amount diorite.By zircon SHRIMP U-Pb dating,drawn adamellite emplacement age of （345.5 ±2.6） Ma-（356.8 ± 5.2） Ma,belongs to the end of the Late Devonian-Early Carboniferous magmatism product. By petrochemistry analysis,SiO2 content are 47.77%-77.11%, Al2O3 content are 12.31% - 16.91%,the average value of Rittman index （σ） is 3.82, the average value of A/NCK （aluminum coefficient） is 0.98,belongs to subaluminous high K Calc alkaline series rock, LREE are enrichment,HREE are deficit,（La/Yb）N average of 8.81, 5Eu average of 0.68,show a weak negative Eu anomaly, trace elements normalized spider diagram shows that Nb,Ta,P, Ti are deficit,Rb,Th,K are enrichment.Through analysis of major element,trace element and REE characteristics, petrochemistry illustrations and the geological background, it is considered that ore-bearing rock and wall rock belongs to I- type island-arc granite,has the Characteristics of mantle-crust mixed environment,tectonic environment is the volcanic-arc environment,and related to the plate subduction.