冀东铧尖金矿金属矿物矿物学特征及成矿作用研究

Research on the Mineralogical Characteristics of Metallic Mineral and Mineralization of Huajian Gold Deposit,Eastern Hebei Province

铧尖金矿位于冀东地区,该地区有丰富的铁矿、金矿资源。研究铧尖金矿床中金属矿物的矿物学特征及其成分的变化,可以深入了解该矿床的形成机制并指导后续找矿。通过野外地质观察、室内光学显微镜观察以及电子探针测试、氢氧同位素和硫同位素测试分析,研究表明:铧尖金矿的载金矿物为黄铁矿和石英,金矿物以含银自然金为主,主要存在于黄铁矿裂隙中或被黄铁矿包裹;黄铁矿中硫的含量平均为52.11%,与硫的理论值相比,黄铁矿普遍亏硫,显示出黄铁矿的形成与热液有关;氢氧同位素δD变化范围为-77.9‰～-68.1‰,δ18O变化范围为9.9‰～15.7‰,硫同位素δ34S变化范围为3.2‰～6‰,表明铧尖金矿的热液来源主要为岩浆水,硫源来自深部岩浆源。综上认为铧尖金矿应为岩浆热液型金矿床。

Huajian gold deposit is located in the eastern part of Hebei Province where contains abundant iron and gold resources. In order to decipher the mechanism of this gold deposit and guide the future mineral deposit exploration,we have studied the metallic mineral characteristics and compositional variations. In this paper, field investigations,microscopic identification and electron microprobe analysis are complished on the metallic minerals in Huajian gold deposit. Hydrogen,oxygen and sulfur isotopes are also analyzed to confirm the source of hydrothermal solution and sulfur of the ore-forming stage. The results suggest that pyrite and quartz are the main gold-bearing minerals in Huajian gold deposit and Au mainly exists as silver-bearing native gold. In this case,silver-bearing native gold generally occurs in the micro-fissures of pyrite or as inclusions in pyrite. The average sulfur value of pyrite is 52. 11% and it is lower than the theoretical value,indicating a magmatic hydrothermal genesis. The δD and δ18 O values of the fluid vary from 77. 9‰ to 68. 1‰,and from 9. 9‰ to 15. 7‰,respectively. The δ34 S values of pyrite vary from 3. 2‰ to 6‰. They indicate that the sources of oreforming solution are mainly magmatic fluid and sulfur is derived from deep-seated magma. We argue that the Huajian gold deposit is a magmatic hydrothermal deposit.