内蒙古东乌旗巴彦都兰铜矿床地质和地球化学特征及其意义

内蒙古巴彦都兰铜矿床位于二连—东乌旗成矿带,该矿区出露下泥盆统泥鳅河组粉砂岩和海西中期黑云母花岗岩体,铜矿体呈脉状产出于泥鳅河组粉砂岩中,严格受断裂控制。主要金属矿物为黄铁矿、磁黄铁矿、黄铜矿等,脉石矿物主要为石英和碳酸盐岩等。矿区黑云母花岗岩La-ICP-MS锆石~(206)Pb/~(238) U加权平均年龄为303.5 Ma±1.1 Ma,铜矿床属于晚古生代构造-岩浆作用的产物。岩石地球化学特征反映黑云母花岗岩属准铝质-弱过铝质高钾钙碱性系列,A/CNK值介于0.99~1.04之间,高碱(w(K_2O+Na_2O)=7.36%~8.73%),富钾(w(K_2O)/w(Na_2O)=1.08~1.66),其形成具有岛弧或后碰撞环境I型花岗岩特征;微量元素特征显示岩体可能形成于后碰撞伸展阶段早期的构造环境中。黄铜矿硫同位素组成介于0.1×10~(-3)~2.1×10~(-3)之间,反映成矿所需的硫可能来自于岩浆,巴彦都兰铜矿区花岗岩很可能是成矿硫的提供者。

Geological and geochemical characteristics of Bayandulan copper deposit, Dong Ujimqin banner, Inner Mongolia and the significance

The Bayandulan copper deposit is located in the Erlian-Dongwuqi metallogenic belt.In the working area are outcropped siltstone of Lower? Devonian Niqiuhe formation and Middle Hercynian biotite granite.Ore bodies occur in the siltstone of Niqiuhe formation and strictly controlled by faults.The main metallic minerals are pyrite,pyrrhotite,chalcopyrite and gangue minerals quartz and carbonatite minerals.Zircons from the biotite granite are analysed for their U-Pb isotopes by La-ICP-MS with the weighted 206Pb/238U average age 303.5 Ma±1.1 Ma,The geochemistry of the rock suggests that the biotite granite belongs to metaluminous to weak peraluminous and high k calc alkaline rock series with A/ CNK values from 0.99 to 1.04,high alkali (ω(K22O+Na2O)=7.36％～8.73％)and K(ω(K2O)/ω (Na2O) =1.08～1.66),characteristic of arc or post-collision I-type granite.Trace element indicated that the granite formed during the early stage of post-collision extension period.The chalcopyrite δ34 SV-CDT values vary from 0.1× 10-3 to 2.1 × 10 3 showing that the sulfur is derived from magma.The biotite granite is the most possible supplier of the sulfur thus the copper deposit is the product of Late Paleozoic tectonic-magmatic process.