流体—硫化物反应实验对福建紫金山铜硫化物矿物组合成因的指示
发布时间：2018-08-07 11:28
【摘要】：福建紫金山铜金矿床是我国最大的浅成低温热液型铜金矿床,金矿下发现的巨大铜矿体对其他同类矿床的指导找矿具有很好的指示意义。我们通过对采集自紫金山矿床的钻孔岩芯磨制的光片进行光学显微镜和电子探针成分分析,发现紫金山矿床中硫化物之间存在着一定的交代、穿插及化学组分的继承关系,依次总结出矿床中硫化物矿物生长及交代的顺序为：黄铁矿-硫砷铜矿-斜方蓝辉铜矿、蓝辉铜矿-铜蓝。同时,我们为模拟黄铁矿在低温酸性含铜流体中反应的过程,设计了水热反应实验,将切割为边长3mmm“立方体”黄铁矿颗粒和1wt%和5wt%浓度的CuSO4溶液封存于消解罐中,再置于100℃、150℃、200℃、250℃的反应釜中,进行15天和30天的低温水热反应。反应之后对反应沥出液进行电感耦合等离子体原子吸收光谱(ICP-AES)分析,并将部分反应残余固体制靶,抛光,置于光学显微镜和扫描电子显微镜(SEM)下观察其生成物形貌特征,电子探针成分分析(EPMA)以确定产物成分、变化趋势和反应过程。水热反应实验结果显示,温度和初始Cu的浓度控制着反应的剧烈程度,温度越高,初始浓度越高,则反映越剧烈,时长则积累了反应变化的效应。反应在低温时(200℃)生成的稳定产物为蓝辉铜矿,在温度较高(200～250℃)时生成的稳定产物为久辉铜矿产物成分从Cu1408到Cu1.96S均有出现,不同成分的产生是反应进行到不同阶段的表现。反应符合耦合的“溶解-再沉淀”机制。结合紫金山钻孔岩芯样品观察结果和室内水热反应模拟实验结果,我们推测矿床经历了两期、四阶段热液事件：第一期第一阶段形成黄铁矿；第二阶段形成硫砷铜矿；第二期第一阶段形成各种铜硫化物,铜蓝在第二期第二阶段形成。其中硫砷铜矿中的砷元素来自于岩浆热液,其显示出交代先成黄铁矿的特征,也有少量结晶于矿石的较大裂缝处形成自形柱状晶体。表生带中的硫化物矿物曝露在地表或潜水中遭受风化剥蚀,逐渐形成高硫型浅成热液,并沿构造裂隙持续下渗至岩体附近受热折返,在下渗和折返的过程中交代先成的黄铁矿和硫砷铜矿。后期的浅成热液逐渐过渡到低温低盐度流体,矿床中生成斜方蓝辉铜矿和蓝辉铜矿等铜硫化物,该交代反应符合耦合的“溶解-再沉淀”的成因机制。热液下渗和受热折返是一个循环往复的过程。
[Abstract]:Zijinshan copper-gold deposit in Fujian Province is the largest epithermal copper-gold deposit in China. The giant copper deposit discovered under the gold deposit has a good instructive significance for the guidance of other similar deposits. By analyzing the optical microscope and electron probe composition of the polished pieces collected from the borehole core of Zijinshan deposit, we find that there is a certain metasomatism, intercalation and inheritance relationship between the sulfides in the Zijinshan deposit. The order of sulphide mineral growth and metasomatism in the ore deposit is as follows: pyrite-arsenite-clinopyranite, blue chalcopyrite-copper blue. At the same time, in order to simulate the reaction process of pyrite in acid copper-bearing fluid at low temperature, the hydrothermal reaction experiment was designed. The pyrite particles cut into the side length of 3mmm "cube" and the CuSO4 solution with the concentrations of 1wt% and 5wt% were sealed in the digestion tank. The reaction was carried out at low temperature for 15 days and 30 days in a reactor at 100 鈩，
本文编号：2169877
[Abstract]:Zijinshan copper-gold deposit in Fujian Province is the largest epithermal copper-gold deposit in China. The giant copper deposit discovered under the gold deposit has a good instructive significance for the guidance of other similar deposits. By analyzing the optical microscope and electron probe composition of the polished pieces collected from the borehole core of Zijinshan deposit, we find that there is a certain metasomatism, intercalation and inheritance relationship between the sulfides in the Zijinshan deposit. The order of sulphide mineral growth and metasomatism in the ore deposit is as follows: pyrite-arsenite-clinopyranite, blue chalcopyrite-copper blue. At the same time, in order to simulate the reaction process of pyrite in acid copper-bearing fluid at low temperature, the hydrothermal reaction experiment was designed. The pyrite particles cut into the side length of 3mmm "cube" and the CuSO4 solution with the concentrations of 1wt% and 5wt% were sealed in the digestion tank. The reaction was carried out at low temperature for 15 days and 30 days in a reactor at 100 鈩，
本文编号：2169877
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