Magnetic mineralogy of the Hongqiling Cu-Ni sulphide deposit: Implications for ore genesis  

作　　者：Xi Aihua Ge Yuhui Cai Yuanfeng Zhang Xuefeng 

机构地区：[1]Faculty of Resources ＆ Environment, Southwest Petroleum University, Chengdu 610500, China [2]State Key Laboratory for Endogenic Metal Deposit Research, Nanjing University, Nanjing 210093, China [3]Department of Natural Resources ＆ Technology Information, China University of Petroleum, Beijing 102249, China

出　　处：《Progress in Natural Science:Materials International》2007年第10期1192-1198,共7页自然科学进展·国际材料（英文版）

基　　金：Supported by National Natural Science Foundation of China (Grant Nos 40572058 and 40672063)

摘　　要：Pyrrhotite is one of the common ore minerals in Cu-Ni sulphide deposits, but only monoclinic pyrrhotite is ferromagnetic at room temperature. X-ray and EPA analyses reveal that most pyrrhotite forming sideronitic texture in the Hongqiling Cu-Ni sulphide de- posit is monoclinic, but that in the massive ore is a mixture of monoclinic and hexagonal pyrrhotites. Differential thermal and magneticthermogravimetric analyses of massive ore indicate a magnetic transition and heat absorption at 323℃, suggesting that this temperature is the thermomagnetic and phase transition point of pyrrhotite. For massive pyrrhotite ores heated at 400℃ for 30 h and then quenched by cool water, the monoclinic pyrrhotite （mpo） transforms completely into the hexagonal pyrrhotite （hpo）. However, all the pyrrhotites resuiting from slow cooling of the sample in air are mpo. These results indicate that transformation between hpo and mpo depends upon the cooling rate. Therefore, massive ores in this deposit might have been formed via rapid cooling of ore melts. On the other hand, it is significant to study the effect of the ratio of the magnetite in total ores on the genesis of magmatic Cu-Ni suphide deposits.Pyrrhotite is one of the common ore minerals in Cu-Ni sulphide deposits, but only monoclinic pyrrhotite is ferromagnetic at room temperature. X-ray and EPA analyses reveal that most pyrrhotite forming sideronitic texture in the Hongqiling Cu-Ni sulphide deposit is monoclinic, but that in the massive ore is a mixture of monoclinic and hexagonal pyrrhotites. Differential thermal and magnetic- thermogravimetric analyses of massive ore indicate a magnetic transition and heat absorption at 323℃, suggesting that this temperature is the thermomagnetic and phase transition point of pyrrhotite. For massive pyrrhotite ores heated at 400oC for 30 h and then quenched by cool water, the monoclinic pyrrhotite (mpo) transforms completely into the hexagonal pyrrhotite (hpo). However, all the pyrrhotites resulting from slow cooling of the sample in air are mpo. These results indicate that transformation between hpo and mpo depends upon the cooling rate. Therefore, massive ores in this deposit might have been formed via rapid cooling of ore melts. On the other hand, it is significant to study the effect of the ratio of the magnetite in total ores on the genesis of magmatic Cu-Ni suphide deposits.

关 键 词：PYRRHOTITE MAGNETITE genesis of Cu-Ni sulphide deposit Hongqiling. 

分 类 号：P571[天文地球—矿物学]