云南澜沧老厂深部斑岩钼(铜)矿成矿物质来源的同位素地球化学证据

通过对云南澜沧老厂深部斑岩钼(铜)矿的S、Pb、H、O同位素地球化学特征的综合分析研究,探讨了隐伏斑岩型矿床的成矿物质来源.研究表明:斑岩钼(铜)矿体主要硫化物的δ34S在3.99‰～+1.8‰之间,平均值为- 1.32‰,分布范围较窄,指示硫具有壳-幔混合源特征；隐伏的成矿花岗斑岩和矿石中主要硫化物的铅同位素组成的变化范围和平均值均具明显的相似性,206pb/204pb比值变化于17.863～ 18.701之间(平均值为18.411),207pb/204 Pb值变化于15.448～15.733之间(平均值为15.628),208 Pb/204 pb值变化于37.753～39.104之间(平均值为38.615),指示矿区斑岩型矿体中的原始铅具有壳-幔混合源的特点,深部地幔也是重要源区之一；斑岩型钼(铜)矿体脉石矿物石英的δ18QH2O在-9.51‰～+9.41‰之间,δD在- 93‰～- 46.2‰之间,指示斑岩矿体成矿流体介质水既有岩浆水又有大气降水,其中,在远离主岩体的外接触带大气降水(雨水)参与成矿的程度相对较高.

Isotopic geochemical evidence of the sources of ore-forming materials for the Laochang deep porphyry Mo(Cu) deposit in Lancang, Yunnan

Based on a comprehensive analysis of S,Pb,H,O isotope geochemical characteristics of the Laochang deep porphyry molybdenum(copper) ore bodies,this paper deals with concealed porphyry metallogenic source material in Lancang of Yunnan Province.Studies show that the main sulfide δ34S values of porphyry molybdenum(copper) ore bodies are between-3.99 ‰ and +1.8 ‰,concentrated in a narrow distribution area,with an average of-1.32‰.The test results of S isotope show the crust-mantle characteristics with the mixture derived from the lower crust and the upper mantle.The main lead isotope 206Pb/204Pb ratios of porphyry molybdenum(copper) ore bodies vary in the range of 17.863～18.701,with an average of 18.411.207Pb/204Pb ratios vary in the range of 15.448～15.733,with an average of 15.628.208Pb/204Pb ratios vary in the range of 37.753～39.104,with an average of 38.615.These data show that lead was derived not only from the formation but also from the ancient continental crust basement located in the lower part of the ore-bearing layer,deep mantle and volcanic magma.The δ18OH2O values of porphyry molybdenum(copper) ore bodies vary between -9.51‰ and +9.41‰,δD values vary between-93‰ and-46.2‰,suggesting that the ore-forming solution of the porphyry ore body was derived from media water from magmatic water and atmospheric precipitation,with the atmospheric precipitation playing the dominant role.