矿床地质2012，Vol.31Issue(6)：1211-1226,16.
海南省后万岭铅锌矿床控矿因素、矿床成因及成矿模式探讨
A tentative discussion on ore-controlling factors, ore genesis and metallogenic model of Houwanling Pb-Zn deposit in Hainan Province
摘要
Abstract
The discovery of the Houwanling Pb-Zn deposit in Ledong County of Hainan Province has been a very im-portant achievement in ore exploration of Hainan Province in recent years. The Houwanling deposit contains proved Pb + Zn metal reserves of 290 thousand tons with average grades of Zn 2.23 % and Pb 0.95 % . The deposit is hosted by the Cretaceous Qianjia pluton which had a crust mantle mixed origin due to intermittent mag-matic intrusion and was produced in a post-collisional extensional environment in middle-late Jurassic period. This calc-alkaline-dominated pluton, which is extremely depleted in Ba, Nb, Ta, Sr, P and Ti and relatively enriched in Rb, K and Pb, shows a shift from high-K to shoshonite association and is characterized by obvious succession in composition and structure. The Qianjia pluton comprises the monzogranite-granodiorite-syenogran-ite association and is geochemically characterized by high REE content (ranging from 122 × 10-6 to 411 × 10-6), moderate to high negative Eu anomalies (δEu = 0.13~0.69) and relatively high LREE/HREE ratios (6.74～16.32). There existed lots of hydrothermal fluids during the evolution of granitic magmas. Furthermore, the abundances of Pb and Zn in rock-forming minerals of the Qianjia pluton's granites are much higher than those in the earth's crust. Deep heat and high content of radioactive heat-producing elements (such as K, Rb) in the shallow part caused convective circulation of hydrothermal fluids in the shallow part, which continuously extracted metallogenic material in a fairly long time. At last, sphalerite and galena were deposited. The deposit is strictly controlled by both the Qianjia pluton and the NNW-nearly SN trending transtensional faults, whereas the ore bodies are largely hosted in the NNW-nearly SN transtensional fault zones or distributed adjacent to the fault zones. Based on thin section observation, the authors obtained abundant important information: course-grained pyrite and fractured pyrite were filled with chalcopyrite, indicating that some of the course-grained pyrite underwent faulting activities, and course-grained pyrite was generated earlier than chalcopyrite with mesh texture at a temperature of 300 ~ 400℃ ; skeletal texture resulted from replacement of course-grained pyrite by sphalerite, indicating that sphalerite was generated after course-grained pyrite; corona texture resulted from replacement of chalcopyrite by covellite, indicating that covellite was generated in the shallow part at a low temperature below 300℃ ; emulsion texture and grating texture resulted from the separation of chalcopyrite from sphalerite, indicating that chalcopyrite - sphalerite solid solution had a initial temperature of about 550℃ . Geological data reveal that the Houwanling Pb-Zn ore deposit probably underwent multistage mineralization and experienced at least more than four main stages of hydrothermal mineralization: ① the generation of course-grained pyrite at early stage of mineralization; ② the deposition of sphalerite mainly at the middle stage of mineralization; ③ the formation of chalcopyrite mainly at the middle or late stage of mineralization; ④ the generation of galena mainly at the late stage of mineralization. The ore-forming fluid might have been released from fractionating porphyry magma. The authors thus consider that the Houwanling Pb-Zn deposit is a hydrothermal vein-type deposit in peripheral or supergene location of the porphyry system, strictly controlled by NNW-nearly SN transtensional faults and formed in an extensional environment of post-collision in late Cretaceous. On such a basis, a metallogenic model to explain ore genesis of the Houwanling Pb-Zn ore deposit is put forward in this paper.关键词
地质学/地球化学/控矿因素/热液脉型矿床/后万岭铅锌矿/千家超单元岩体/海南省Key words
geology/ geochemistry/ ore-controlling factor/ hydrothermal vein-type deposit/ Houwanling Pb-Zn deposit/ Qianjia pluton/ Hainan Province分类
天文与地球科学引用本文复制引用
付王伟,许德如,傅杨荣,杨昌松,周迎春,杨东生,吴传军,王智琳..海南省后万岭铅锌矿床控矿因素、矿床成因及成矿模式探讨[J].矿床地质,2012,31(6):1211-1226,16.基金项目
本文得到海南省资源潜力评价项目(编号:1212010881625)资助 （编号:1212010881625）
