中国红透山太古宙块状硫化物矿床的变质——重就位

THE METAMORPHISM AND REEMPLACEM ENT OF THE ARCHEAN HUNGTOUSHAN MASSIVE SULFIDE ORE DEPOST, NORTH LIAONING PROVINGE, CHINA

红透山太古宙锌——铜型块状硫化物矿床,经历了多次变质和多期变形作用。目前所保留的矿貌,主要是早太古宇晚期,第二次变质和形变作用造成的。 该矿床遭受第二次较强变形 (500℃—700℃中压条件) 过程中,硫化物矿物朝迭加褶皱和塑性断层所造成的低压区、进行物理迁移(主要为塑性流动)。物理迁移是由处于脆性状态的黄铁矿和部分脉石矿物,发生破裂,与具有不同程度塑形的硫化物矿物等一起产生的迁移。由于主要是硫化物矿物的脆性—延展性转化点的不同,导致了此过程中出现再活化差异迁移。 参照不同硫化物的脆性——延展性转化点的实验数据,结合它的在再就位过程中的先后穿切关系,区内主要硫化物矿物的再活化能力由小到大的序列为。黄铁矿——磁黄铁矿——闪锌矿——黄铜矿。 主要由硫化物矿物组成的矿体的变质——重就位可理解为:较强塑性变形过程中,不仅矿体发生了相对位移,而且组成矿体的各种硫化物矿物,尚发生了差异性的再活化迁移,从而造成矿体形状、产状、分布特点及矿石组构等一系列矿床地质特征变化的过程。 各种硫化物矿物的脆性——延性的转化点不同,矿体、围岩及矿体内部组成间的物理性质差异及低压区的存在是变质——重就位的必要条件。硫化物矿体物理性质的变质——重就晓,对变质成矿作用来说?

The Hungtoushan Archean massive Zinc-copper sulfide deposit had undergone multistages of metamorphism and deformation. The aspect now it reveals was the resultant of the 2nd stage of metamorphism and stractural deformation held in the late period of early Archaeozoic era.In the course of the second stage of deformation(under 500℃-700℃ and moderate pressure) thesulfide minerals migrated in the form of plastic flow to the low pressure zone resulted by folding and ductile faulting. The plastic migration was conducted by the broken up of the brittle pyrite and sonce gangminerals and with the mobilization of sulfide minerals during the deformation and to the differen 1behavior in plastic yielding of the main sulfide minerals a rather differen-tial mi gration was happened.In combining the experimental data of the yielding point of the varied sulfide minerals with the field observation of their crossing relationship the mobility of the mairi sulfide minerals are arranged in an increasing order as: pyrite-pyrrhotite-sphalerite-chalcopyrite.The metamorphism and leemplacement of the sulpide ore body may be conceived as a process in which not only the whole ore body but also the individual constituent minerals had been involved in differential movement with the result of a series of change in shape, occurrence and mineras composition of the ore. And all of these is conditioned by the differences in yielding point and physical properties of the minerals and rocks of the ore deposit and by the existence of a low pressure region, The subject presented here may be of some significance in the study of metamprphic mineralization both in theory and in practice.