地质科技通报2024，Vol.43Issue(2)：123-142,20.DOI:10.19509/j.cnki.dzkq.tb20220519
湖南铜山岭层状钨多金属矽卡岩形成时代、成因机制及其找矿启示
Timing and genesis of the Tongshanling stratiform W-Mo skarn deposit in Hunan Province:Implications for exploration
摘要
Abstract
[Objective]The Tongshanling deposit in the western Nanling metallogenic belt of Hunan Province is a skarn Cu polymetallic deposit related to Ⅰ-type granodiorite.Recently,a thick stratiform W-Mo skarn ore body has been found in the limestone of the Qiziqiao Formation far from the granodiorite intrusion.Its geological characteris-tics,mineral assemblages and genetic types are different from those of the ore bodies in the contact zone of the in-trusion.[Methods]In this study,timing and genesis of the Tongshanling stratiform are analysed,through field in-vestigation,microscopic identification,in situ U-Pb dating of garnet,and LA-ICP-MS trace element analysis of scheelite.[Results]The following four stages of mineralization are identified:garnet skarn,epidote and chlorite skarn,quartz sulfide and quartz calcite.The U-Pb concordant age of garnet is(160.4±4.2)Ma(MSWD=0.79),is significantly later than that of the granodiorite(～167 Ma)and similar to that of the granite porphyry(～161 Ma).The total rare earth element(ΣREE)distribution pattern of the garnet core is light rare earth element(LREE)enrichment and heavy rare earth element(HREE)flat and is similar to the whole-rock ΣREE model of granite porphyry.The ΣREE distribution pattern of garnet rims is LREE-depleted and is different from that of garnet in contact zone skarns.Scheelite associated with epidote can be divided into three stages.ΣREE modes of the three stages are all LREE enrichment and HREE depletion,but the ΣREE content decreases significantly from the first stage(Sch1-a,332× 10-6-353× 10-6)to the second stage(Sch1-b,144×10-6-301 × 10-6)and the third stage(Sch1-c,4.05×10-6-31.8×10-6).Scheelite associated with chlorite(Sch2)shows LREE enrichment and HREE depletion,and their ΣREE content is 51.2× 10-6-139×10-6.W-Mo mineralization is mainly concentrated in the retrograde stage.The Sch1-b and Sch2 stages have higher oxygen fugacities are the main stage of W mineralization,while the other stages(Sch1-a and Sch1-c)with lower oxygen fugacities are the main stage of Mo mineralization.Comprehensive analysis reveals that the stratiform skarn and contact zone skarn in the Tongshanling and Weijia de-posits are different metallogenic systems.The stratiform skarn may be related to the granite porphyry with a relative-ly high degree of fractionation.[Conclusion]More attention should be given to the late granite porphyry in deep within and at the edge of the Tongshanling deposit.关键词
层状矽卡岩/石榴石/白钨矿/LA-ICP-MS/湖南铜山岭Key words
stratiform skarn/garnet/scheelite/LA-ICP-MS/Tongshanling in Hunan Province分类
天文与地球科学引用本文复制引用
谭富诚,孔华,刘飚,吴堑虹,刘玉国,杨齐智..湖南铜山岭层状钨多金属矽卡岩形成时代、成因机制及其找矿启示[J].地质科技通报,2024,43(2):123-142,20.基金项目
国家重点研发计划(2018YFC0603901) （2018YFC0603901）
中南大学研究生自主创新项目(2022ZZTS0458) （2022ZZTS0458）
