浙江建德铜矿流体包裹体研究

Fluid Inclusion Studies of the Jiande Copper Deposit,Zhejiang Province,China

浙江建德铜矿（原名岭后铜矿） 是20世纪60年代初期探明的中型铜矿,位于扬子板块和华夏板块结合带（即钦杭结合带） 北东段.文中系统研究了建德铜矿主成矿期块状矿石石英中的流体包裹体.岩相学研究表明主要发育三类包裹体：包括富液相包裹体（I型）,富气相包裹体（II型）,以及含子晶包裹体（III型）;显微测温结果显示：I类富液相包裹体加热后均一到液相,均一温度分布范围主要集中在280-340℃,流体包裹体盐度0.63-8.00 wt.% NaCl eqv,II类富气相包裹体加热均一到气相,均一温度296-334℃,盐度1.22-2.00 wt.% NaCl eqv的低盐度范围,III类含子晶包裹体,均一温度范围与II类包裹体基本相同,介于290-326℃,盐度则较高,介于31.87-38.16 wt.% NaCl eqv.激光拉曼探针分析揭示,流体挥发分主要为水蒸气,同时部分包裹体气相组分中含有CO2、CH4、N2.II类与III类流体包裹体在视域内共存,且两者均一温度相似,盐度相差很大,表明强烈的流体沸腾作用发生.流体强烈沸腾作用是造成建德铜矿成矿物质沉淀富集的原因.成矿流体研究结合地质特征表明,建德铜矿是燕山期的矽卡岩型矿床而不是海西期的喷流沉积矿床.

Jiande copper deposit in Zhejiang Province was found in the 1960, and it is located in the northeastern part of Qinzhou-Hangzhou suture belt between Yangtze and Cathaysia blocks. Research about ore-forming fluids on it is still lacking. This study made a systematic investigation of fluid inclusions in the Jiande copper deposit. Based on petrographic observations of ore-bearing quartz collected from the massive ores, there are three types of primary inclusions of Jiande deposit:two-phase liquid-rich (type Ⅰ), two-phase vapor-rich (type Ⅱ), and halite-bearing (type Ⅲ) fluid inclusions. Type Ⅰ inclusions occur widely in the Jiande deposit and show homogenization temperatures of 220~377℃ and salinities of 0.63~8.00 wt.%NaCl equivalent. Type Ⅱ and type Ⅲ inclusions primarily coexist in ore veins. Homogenization temperatures of type Ⅱ and type Ⅲ reveal peak temperatures at 296~334℃and 290~326℃, respectively, and their salinities at 1.22~2.00 wt.%NaCl and 31.87~38.16 wt.%NaCl, respectively. The results indicate that fluid boiling process took place, and metal precipitation was probably induced by extensive fluid boiling events during the ore stage. Raman analysis of fluid inclusions indicates that, in the gaseous phase, water is dominant with small amount of CO2, CH4, and N2. Our study suggests that the Jiangde copper deposit is a Yanshanian Skarn deposit rather than a Hycernian Sedex Cu deposit.