贵州罗甸软玉矿床地球化学特征及成矿机制研究

Nephrite is a valuable jade forms under greenschist facies metamorphic conditions. Luodian is a newly discovered nephrite deposit which forms in the contact alteration zone of (255.0±0.62Ma) diabase and limestone of Permian Sidazhai Group. The white, cyan, bluish-white and spotted ore are dominant type in the mine. The high quality nephrite normally occurs away from diabase and quality and scale of nephrite in southern belt is better than northern. Although many previous studies have been carried out, the source of ore forming elements, evolution history of fluids, and genetic links between magmatism and mineralization, are still controversial. Taking Luomu, Luokun, baiyun, E’cun and Rongli nephrite deposit as examples, a combination use of geochronology, trace element geochemistry, isotope geochemistry, and microthermometry on both ores and country rocks will better understand the metallogenic mechanism of Luodian nephrite. Finally, we try to establish an updated genetic model for the nephrite mineralization. These studies will support prospecting and exploration of similar deposit in the Guizhou-Guangxi adjacent area.

软玉是一种重要的宝玉石类型，通常形成于绿片岩相之下的变质环境中。近年来新发现的罗甸软玉矿矿体产出于辉绿岩（255.0±0.62Ma）与二叠纪四大寨组灰岩接触部位的上覆围岩蚀变带中。玉石类型有白玉、青玉、青白玉和花斑玉。优质软玉矿体的产出远离辉绿岩体，且矿区内南部矿体产出的玉石在质量和规模上优于北部矿体。尽管前人做了大量工作，也取得了很多进展，但在成矿年龄、成矿物质来源、成矿流体演化以及岩浆岩与成矿耦合关系等方面还存在诸多争议。本项目选取矿区内罗悃、罗暮、白云、峨村和冗里矿床为研究对象，系统采集矿石、赋矿围岩、岩浆岩样品进行年代学、元素地球化学、同位素地球化学和流体包裹体的研究，旨在解决如上争议，建立成矿模式，丰富软玉成矿理论并为贵州南部、广西北部地区同类型矿床的寻找提供理论指导。