摘要
在诸如沉积型层状铜矿、浅成低温热液型矿床、与火山岩有关的块状硫化物矿床等中常出现黄铁矿、铜(铁)硫化物、铁氧化物等矿物的共生现象,研究这些矿物组合的形成机制对于认识这一系列矿床中矿石矿物的成因具有重要意义。本文以矿物—流体相互作用伴随物质溶解—再沉淀为理论基础,在水热条件下,以黄铁矿为初始矿物,Cu(Ⅰ)—Cl为溶液中Cu的形态,通过设置不同的p H、反应温度、Cu(Ⅰ)—Cl浓度研究了这些矿物组合的形成规律。实验结果表明:1黄铜矿、斑铜矿等铜铁硫化物主要出现在弱酸性环境中,蓝辉铜矿等铜硫化物可出现在弱碱性环境中;2温度较低时(约100℃)黄铁矿主要转变为赤铁矿等铁氧化物。不同实验条件下形成的矿物组合与已知矿床中发现的矿物组合具有高度的相似性,因此可以用特定矿物组合的实验条件模拟和反演矿床形成的物理化学环境。
In some ore deposits, such as Sediment hosted Stratiform Copper deposits, Epithermal Copper deposits and Volcanic associated massive sulfide deposits, the assemblage of pyrite, copper （iron） sulfides, iron oxides often occurs. The study of this assemblage is important to understand the genesis of the ore mineral in those types of ore deposit. In this paper, we consider the theory of mineral—fluid interaction. This process may involve dissolution—reprecipitation reaction giving rise to transformation of some ore formation elements. We use pyrite as the parent mineral and Cu（I）—Cl as the cupreous speciation to study the assemblage and reaction mechanism on the interface between mineral and fluids.Methods： We conduct our reaction in a 10 mL PTFE tube. Every 6mL pH buffer solutions and a cubic pyrite were used. The cubic pyrite can record morphological changes before and after reaction. The hydrothermal reaction occurred in anaerobic conditions. And the reactions are in different temperature, different pH, different reaction time and different concentration of Cu（I）—Cl solution. X ray Diffractometry （XRD）, Electron Probe Microanalysis （EPMA）, Scanning Electron Microscopy （SEM） and Laser Raman Microprobe （LRMP） were used to study the transformation of the product and the structure during the reaction.Results： The results show that the species of the reaction product differs at different temperature, different pH and different reaction time. The main products are chalcopyrite, bornite, digenite, anilite, hematite and magnetite. The hematite can form in different temperature and different pH. There would be more in low temperature and most of the hematite nucleate on the bottom and wall of the PTFE tube. Chalcopyrite and bornite can form in mild acid conditions while digenite forms in mild basic conditions. At low temperature （about 100℃ ） the pyrite mainly converts to hematite. Furthermore, the results show that the trace element of parent mineral can be inherited by daughter phase and the processes are pseudomorphic reactions.Conclusions： The mineral assemblage obtained in our experiment is similar to the one in some deposits in nature. This may suggest that this type of copper deposits has a similar forming conditions to our experiment.
出处
《地质论评》
CAS
CSCD
北大核心
2016年第4期997-1009,共13页
Geological Review
基金
国家自然科学基金资助项目(编号:41272055)的成果~~
关键词
黄铁矿
水热实验
铜铁硫化物交代产物
溶解-再沉淀耦合机制
pyrite hydrothermal experiment products of copper iron sulfide the coupled dissolution-reprecipitation mechanism
