冀东峪耳崖金矿床金属矿物特征及其组合意义

Mineralogical characteristics of metallic minerals in Yuerya gold deposit of eastern Hebei Province and their combination significance

峪耳崖金矿床是冀东地区重要的金矿床之一。研究峪耳崖金矿床中金属矿物成分的变化及元素赋存状态,对了解矿床的形成机制及指导找矿具有重要意义。本次工作应用光学显微镜和电子探针(EPMA)对峪耳崖金矿床中的金属矿物进行了研究,并应用氢、氧及硫同位素分析对峪耳崖金矿床的成矿热液来源及硫源进行了探讨。该矿床的载金矿物有石英、黄铁矿、碲铋矿,金矿物为银金矿。其中,黄铁矿的w(S)平均为52·34%,与理论值相比,其普遍亏硫,显示出成矿与热液有关。碲铋矿是本次工作重点研究的载金矿物,与金的产出具关联性。被碲铋矿包裹的银金矿的w(Au)要高于被黄铁矿包裹的银金矿的w(Au)。据氢、氧及硫同位素测试结果认为,峪耳崖金矿床的热液来源主要为岩浆水,硫来自深部岩浆源。结合黄铁矿、黄铜矿、闪锌矿、方铅矿、碲铋矿和银金矿等的矿物学特征及组合意义推断,峪耳崖金矿床为中-深成中温岩浆热液矿床,并认为其深部找矿可关注Te、Bi富集异常的区段。

The Yuerya gold deposit is one of the important gold deposits in eastern Hebei Province. The study of the compositional variations of metallic minerals and the mode of occurrence of elements from the Yuerya gold deposit is of great significance in further understanding the metallogenic mechanism and providing the basis for further prospecting. The research on metallic minerals of the Yuerya gold deposit was carried out by means of field survey and microscopic study as well as the Electron Probe Micro Analysis （EPMA）. Hydrogen, oxygen and sulfur isotopes were also analyzed to probe into the sources of ore-forming hydrothermal fluids and sulfur. The gold-bearing minerals of the Yuerya gold deposit include quartz, pyrite and tellurobismuthite, and the gold mineral is electrum. The sulfur average content of pyrite is 52.34 wt%. A comparison with the theoretical content of sulfur shows that the pyrite from Yuerya gold deposit is generally sulfur depletion, suggesting that the mineralization of deposit was related to the hydrothermal fluid. This study laid emphasis on the gold-bearing mineral tellurobismuthite which belonged to the medium and high temperature mineral and had certain genetic relationship with the formation of electrum. Based on a comparison between the amount of gold carried by electrum in pyrite and that in tellurobismuthite, the authors have come to the conclusion that the amount of gold carried by tellurobismuthite was greater than the amount of gold carried by pyrite. By analyzing hydrogen, oxygen and sulfur isotope, the authors consider that the ore-forming fluid came from magmatic water, and the sulfur came from deep-seated magma. Taking the mineralogical characteristics and combination signicance of pyrite, chalcopyrite, sphalerite, galena, tellurobismuthite and electrum into account,the authors hold that the Yuerya gold deposit belongs to middle-deep medium temperature magmatic hydrothermal deposit, and that we should pay special attention to the enrichment area of Te and Bi in the prospecting for deep ore bodies.