钦杭成矿带南段旗鼓岭铜钨钼多金属矿床的辉钼矿Re-Os同位素年龄及成矿物质来源

Re-Os Age of Molybdenite and Ore-Forming Material Source of the Qiguling Cu-W-Mo Polymetallic Deposit in the Southern Section of the Qinghang Metallogenic Belt

广东旗鼓岭铜钨钼多金属矿是近年来在云开地区新发现且具有重要找矿远景的矿床之一。矿体形态不规则,主要呈层状、似层状和透镜状产出在矽卡岩中。本文在详细了解矿床地质特征的基础上,通过辉钼矿Re-Os同位素定年技术首次对旗鼓岭矿床进行了成矿时代的厘定。5件辉钼矿样品的模式年龄为163.6~165.3Ma,加权平均年龄为164.54±0.94 Ma,表明旗鼓岭铜钨钼多金属矿床成矿作用发生于中侏罗世晚期。该矿床辉钼矿样品的Re含量变化于76.86~86.22μg/g之间,表明其成矿物质具有壳幔混源的特征。黄铁矿的δ^(34)S组成范围比较窄,变化范围为1.4‰~2.5‰,显示来自于岩浆热液。旗鼓岭铜钨钼多金属矿床成矿年龄的厘定为下一步在区内开展150~170 Ma左右的斑岩-矽卡岩多金属矿床找矿勘探提供了重要的线索,也标志着著名的钦杭成矿带进一步向南延伸,同时为进一步深入研究钦杭成矿带成岩成矿作用提供了新的资料和证据。

The Qiguling Cu-W-Mo polymetallic deposit, located in the Yunkai area, is one of the newly discovered deposits with huge prospecting potential. The ore bodies mainly occur as lamellar, stratiods and lenses in skarn. Based on detailed geologic characteristics of the deposit, this study re-determined the metallogenic time of the Qiguling deposit using molybdenite Re-Os dating technology. Precise Re-Os dating of molybdenite shows that the Re-Os model ages of five samples range from 163.6 Ma to 165.3 Ma, with a weighted mean age of 164. 54±0. 94 Ma, indicating that the timing for Cu-W-Mo polymetallic mineralization formed in the late stage of the Mid-Jurassic. Rhenium content of molybdenum in the samples ranges from 76.86-86.22 /,g/g, and this indicates the ore-forming material is characterized by crust and mantle mixing in origin. 834 S values of pyrites of this deposit have a narrow range of 1. 40/000 - 2. 50/000, showing magmatic sulfur. Determination of metallogenic time for the Qiguling Cu-W-Mo deposit not only provides an important clue to future prospecting for 150-170 Ma porphyry-skarn Cu polymetallic deposits in this area, but also marks the southward extension of the well-known Qinhang metallogenic belt. Therefore, this study offers new information for further research of diagenesis and metallogenesis of the Qinhang metallogenic belt.