山东范家庄金矿床S、Pb同位素组成及对成矿物质来源的示踪

Sulfur and Lead Isotopic Compositions of the Fanjiazhuang Gold Deposit and Their Implications for Sources of Ore-Forming Materials, Shandong Province

范家庄金矿床是胶东地区牟乳金成矿带新近发现的一个金矿床。通过S、Pb同位素的对比与分析,对范家庄金矿床的成矿物质来源进行了探讨和研究。研究结果表明,范家庄金矿床矿石硫化物δ34S值总体为9.8‰~12.3‰,极差为2.5‰,平均值10.9‰,具有岩浆热液硫的特征,且与其伴生的中基性脉岩相近,说明范家庄金矿床的矿石硫主要来自于岩浆热液,并与其伴生的中基性脉岩具有相应的继承性。硫化物矿石铅206Pb/204Pb=17.110~17.600,207Pb/204Pb=15.444~15.532,208Pb/204Pb=37.578~37.986,将数据投影到铅构造模式图上,成分点均落在地幔铅与造山带铅平均演化带之间,显示范家庄金矿床铅具有壳幔混合来源特征。硫、铅同位素反映范家庄金矿床的成矿物质来源于地壳和地幔的混合,且以地幔物质为主。

The Fanjiazhuang gold deposit is a newly discovered gold deposit in the gold ore-forming belt of Muping-Rushan of Jiaodong area.This article discusses and researches the material source of Fanjiazhuang gold deposit by contrasting and studying sulfur and lead isotopes.This study suggests that the mineral sulfur of Fanjiazhuang gold deposit mainly comes from magmatic hydrothermal fluid,and the middle-base vein rocks have corresponding inheritance,for the sulfideδ34S of deposit in Fanjiazhuang is characterized by magmatic hydrothermal sulfur,and is closed to the intermediate-base vein rocks where it is found in.The sulfide ore 206Pb/204Pb,207Pb/204Pb,and 208Pb/204Pb ratios in the Fanjiazhuang gold deposit are 17.110-17.600,15.444-15.532 and 37.578-37.986,respectively.This shows that the lead isotope in Fanjiazhuang has the characteristics of mixed mantle-and crust-derived sources.The sulfur and lead isotopes reflect that the ore-forming materials of Fanjiazhuang gold deposit are from the mixing of the mantleand crust-derived sources,dominated by the mantle.