投稿时间：2023-08-15
修订日期：2024-01-26
网络发布日期：2024-04-25
中文摘要:龙玛拉铅锌多金属矿床是冈底斯成矿带东段北缘念青唐古拉矽卡岩型多金属成矿带一个典型的铅锌矿床，矿床以铅锌银矿化为主，伴生铁铜矿化，具有矿化元素丰富，品位高的特点。矿体在纵向上发育明显的矿化分带，从矿体顶部向下依次发育铅锌银矿化、锌铜矿化、铁铜矿化和铁矿化，表现出从矿体顶部到矿体，从低温到高温的元素和矿物组合的分布规律。镜下鉴定及电子探针分析结果表明，矿床主要金属矿物有方铅矿、闪锌矿、黄铜矿、黄铁矿、磁黄铁矿和磁铁矿，同时存在少量的斜方辉铅铋矿、自然铋等铋矿物以及白铁矿、铜蓝、孔雀石等次生矿物，金属矿物间具有复杂的穿插交代关系，根据详细的野外观察和镜下鉴定厘清了矿物生成顺序。黄铁矿Co/Ni比值集中在1~5之间，显示出岩浆热液成因的特点，其Fe/（S+As）比值和胶状黄铁矿的出现暗示矿床形成于中浅成环境，闪锌矿富Fe、Mn，多为铁闪锌矿，表明其形成于中高温环境，按照Fe元素温度计估算出闪锌矿成矿温度为259~305℃，磁黄铁矿以单斜磁黄铁矿为主，为低温成因，且在浅部围岩和矿体中均大量出现，显示出成矿流体运移至近地表后快速降温，在强还原条件下发生了硫化物沉淀，龙玛拉矿床为远端岩浆热液矽卡岩型矿床。矿床中铋矿物与银具有密切的时空关系，指示铋对银的富集可能具有重要作用，对该带银成矿规律的研究具有一定的指示意义。
Abstract:The Longmala lead-zinc polymetallic deposit is a typical Pb-Zn deposit in the Nyainqentanglha skarn type polymetallic metallogenic belt on the northern margin of the eastern Gangdise metallogenic belt. The deposit is dominated by lead-zinc-silver mineralization, accompanied by iron-copper mineralization, and characterized by rich mineralized elements and high grade. Obvious mineralization zonation is developed vertically in the deposit. Lead-zinc-silver mineralization, zinc-copper mineralization, iron-copper mineralization and iron mineralization are successively developed from the top to foot of the orebody, indicating the element combination and mineral association were developed from low temperature to high temperature from the top to foot of the orebody. The results of microscopic identification and electron probe analysis show that the main metal minerals of the deposit are galena, sphalerite, chalcopyrite, pyrite, pyrrhotite and magnetite, as well as minor bismuth minerals such as cosalite, natural bismuth and secondary minerals such as marcasite, covellite and malachite. The ore minerals have a complex intersperses metasomatism relationship, which is studied from detailed field observation and microscopic identification, and the mineral paragenesis was clarified. The Co/Ni ratio of multi-stage pyrite is concentrated in the range of 1~5, showing the characteristics of magmatic hydrothermal origin, and the Fe/(S+As) ratio and colloidal pyrite suggest that the deposit was formed in a mesogene to hypabyssal environment. Sphalerite in the Longmala deposit is rich in Fe and Mn, mostly marmatite, indicating that it was formed in a medium to high temperature environment. The Fe element thermometer estimates that the metallogenic temperature of spha-lerite is 259~305℃. The pyrrhotite is mainly monoclinic pyrrhotite and it occurs in abundance in both ore bodies and sand slate, indicating that ore forming fluids cooled rapidly after moving to the surface. Sulfide precipitation occurred under strong reduction condition. The Longmala deposit is a distal magmatic hydrothermal skarn depo-sit. The bismuth minerals in the deposit have a close relationship with silver, which indicates that bismuth may play an important role in silver enrichment, and has certain indicative significance for the study of silver minera-lization in this belt.
keywords:distal skarn deposit mineralization zonation mineralogy of metal minerals bismuth minerals Longmala deposit Gangdise metallogenic belt
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基金项目:本文得到国家自然科学基金（编号：41902095）和国家重点研发项目（编号：2022YFC2905002）联合资助
引用文本：
孙杨,周敖日格勒,谢富伟,王立强,何逸飞,张冠,林文海.2024.西藏龙玛拉矽卡岩型铅锌多金属矿床金属矿物特征及地质意义[J].矿床地质,43(2):304~318SUN Yang,ZHOU Aorigele,XIE FuWei,WANG LiQiang,HE YiFei,ZHANG Guan,LIN WenHai.2024.Metallic minerals characteristic and geological significance of Longmala skarn type Pb-Zn polymetallic deposit in Xizang[J].Mineral Deposits43(2):304~318
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