青城子姚家沟钼矿床硫、铅同位素组成及其地质意义

Characteristics and geological significance of sulfur and lead isotope compositions of Yaojiagou Molybdenum Deposit in Qingchengzi

对辽东青城子姚家沟钼矿床金属硫化物进行硫、铅同位素测量,探讨成矿物质来源。研究结果表明,金属硫化物δ34S值变化范围为2.0‰~3.9‰,显示岩浆硫的特点。矿石^(206)Pb/^(204)Pb=17.452~18.854,^(207)Pb/^(204)Pb=15.474~15.669,^(208)Pb/^(204)Pb=37.739~39.097。铅同位素Th/U比值范围为3.74~3.94,μ值介于9.34~9.56,均低于9.58,介于地壳与原始地幔值之间,反映矿石铅具深源铅和壳源铅特征。根据铅同位素特征参数和判别图解,结合矿床成矿背景和矿床成因,认为姚家沟钼矿铅同位素组成具混合铅特征,这种混合受俯冲造山作用控制,是一种与岩浆作用有关的壳幔混合铅的成矿作用。

The sulfur and lead isotope of the metal sulfides in Yaojiagou Molybdenum Deposit are analyzed in order to ascertain the origin of the ore-forming materials.The results show that the δ34 S values of ore range from2.0‰to 3.9‰.It is inferred that the sulfur may be derived mainly from deep source related to magmatic activity.The ^（206）Pb/^（204）Pb,^（207）Pb/^（204）Pb and ^（208）Pb/^（204）Pb ratios of sulfide ores vary in the range of 17.452~18.854,15.474~15.669 and 37.739~39.097,respectively.The Th/U values of the lead isotope range from 3.74 to 3.94,theμvalues range from 9.34 to 9.56（9.58）between the values of the crust and mantle,indicated that the ore lead is characterized by both deep-sourced and crust-sourced origins.According to the characteristics of parameters,omposition model of the lead,combined with the metallogenic setting and ore deposit genesis of Yaojiagou Molybdenum Deposit,it is concluded that the lead of Yaojiagou Molybdenum Deposit are mainly derived from crust-mantle mixing,which is controlled by subduction orogeny.