【摘要】 内蒙古鸡冠山钼矿床位于中亚-蒙古巨型造山带东段,是西拉沐沦钼金属成矿带中典型的大型斑岩型钼矿床。矿床产于燕山晚期火山侵入杂岩中,矿体与岩体关系密切,矿化类型以细脉浸染状斑岩型矿化为主。在野外地质观察的基础上,本文对矿石矿物黄铁矿、辉钼矿进行了S同位素组成分析,对矿床围岩全岩及黄铁矿单矿物进行了Pb同位素组成分析。结果表明,钼矿石δ³⁴S变化范围为4. 617‰～7. 072‰,平均值为5. 653‰,离散度小,硫化物δ³⁴S值全为正值,表明矿石中S源是均一的。辉钼矿δ³⁴S变化范围为4. 617‰～5. 351‰,平均值为4. 875‰。硫同位素比值5. 653‰具花岗质岩浆硫特征,推测其硫可能主要来源于下地壳岩浆源,并有一定量的地幔物质混入。全岩的²⁰⁶Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb和²⁰⁸Pb/²⁰⁴Pb分别为17. 876～19. 618、15. 519～15. 609和38. 111～40. 408,表明鸡冠山钼矿床围岩的全岩铅同位素组成均变化较大。矿石矿物黄铁矿的²⁰⁶Pb/²⁰⁴Pb、²⁰⁷Pb/²⁰⁴Pb和²⁰⁸Pb/^{20 4}Pb分别为17. 781～17. 830、15. 523～15. 526和38. 084～38. 102,表明矿石矿物铅同位素组成变化较小。围岩全岩和矿石硫化物的铅同位素投影点均落在造山带演化线的下方,表明铅很可能源于地幔或者下地壳。更多还原

【Abstract】 The Jiguanshan molybdenum deposit in Inner Mongolia is located in the Xilamulun Mo metallogenic belt,eastern section of the Central Asia-Mongolia orogen. It occurs within a volcanic-intrusive complex of the Late Yanshan period,characterized by the veinlet and disseminated mineralization. On the basis of field geological observation,this work has made analysis of S isotope composition to its pyrite and molybdenite and Pb isotope to whole rock of surrounding rock and single mineral of pyrite. Results show that the sulphide δ³⁴S values are all positive,ranging in 4. 617‰ ～ 7. 072‰,with a mean value of 5. 653‰ and a small discrete degree,implying uniformity of S in the ore source. In molybdenite,δ³⁴S changes in 4. 617‰ ～ 5. 351‰,4. 875‰ on average. The sulfur isotope ratio is 5. 653‰,a feature of granitic magma sulfur,presumably mainly coming from magma in lower crust with a certain amount of mantle material mixed. Whole rock ²⁰⁶Pb/²⁰⁴Pb,²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb are 17. 876 ～ 19. 618,15. 519 ～ 15. 609 and 38. 111 ～40. 408,respectively,showing that the lead isotopic composition of whole rock in this deposit is highly variable. In the ore mineral of pyrite,²⁰⁶Pb/²⁰⁴Pb,²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb are 17. 781 ～ 17. 830,15. 523 ～ 15. 526 and 38. 084 ～ 38. 102,respectively,indicating small changes of Pb isotopic composition. The projection points of Pb isotope of both the whole rock of country rock and ore sulfides are below the evolution line of the orogenic belt,suggesting that the Pb probably originated from mantle or lower crust.更多还原