Fluid inclusion study of carbonatite dykes/veins and ore-hosted dolostone at the Bayan Obo ore deposit

详细信息   全文下载|推荐本文 |

• 出版年：2007
• 作者：QIN Chaojian；QIU Yuhuo；ZHOU GuoFu；WANG ZhongGang；ZHANG TaiRong；XIAO GuoWang
• 单位1：State Key Lab of Ore Deposit Geochemistry，Institute of Geochemistry,Chinese Academy of Sciences
• 语种：英文
• 作者关键词：Fluid inclusion；Carbonatite dyke；Ore-hosted dolostone；Origin；Bayan Obo deposit
• 起始页：161
• 总页数：8
• 刊名：岩石学报
• 是否内版：否
• 刊频：月刊
• 创刊时间：1985
• 主办单位：中国矿物岩石地球化学学会；中国科学院地质与地球物理研究所
• 电子信箱：Ihzd@ public.tpt.tj.cn
• 卷：23
• 期：1
• 期刊索取号：P350.66357

摘要

Fluid inclusion study has been carried out for the carbonatite dykes/veins and the ore-hosted dolostone of the Bayan Obosuperlarge REE-Fe-Nb deposit in order to provide the evidence and constraint for their origin. Based on the detailed geologicalobservation and mineralogical investigation, the heating and cooling stage and laser Raman spectroscopy were mainly used for thelaboratory work of this study. Following results have been obtained: (1) The discovery of melt and melt-fluid inclusions fromcarbonatite dykes/veins in the Dulahara and Jianshan Mountains, combined with the fine-grained (aplitic) texture of rocks, as well asthe types and features of fluid inclusions such as CO₂ enrichment, higher homogenization temperature, provides a direct evidence forthe magmatic origin of these dykes/veins.(2) The carbonatite dykes/veins distributed in two regions, nearby the axis of the Kuangouanticline and in the east to Bayan Obo town, mainly show coarse-grained texture. No melt inclusion was found, and the fluid inclusionspossess features of less CO₂ , lower homogenization temperature and higher salinity. They are tentatively identified as veins formed bysome carbonate-rich hydrothermal solution.(3) Bedding carbonate layers/lens within the hanging wall and foot wall of ore-hosteddolostone, previously recognized as of magmatic origin, mainly composed by dolomite. The existence of single phase pure aqueousinclusions with very low homogenization temperature indicates their sedimentary origin.(4) The ore-hosted dolostone possessesapparent bedding and laminated structures. No melt inclusion was found, but, both single phase pure aqueous inclusions and CO₂bearing multi-phase fluid inclusions coexisted in dolostones. In the direction towards ore-bodies, the homogenization temperature andCO₂ contents of fluid inclusion show an increasing tendency. It indicates the sedimentary origin of dolostone superimposed by late fluidmetasomatism.