摘要
与基性-超基性岩有关的岩浆熔离铜-镍矿床和岩浆铬铁矿矿床成岩成矿作用中铂族元素地球化学性状的研究，已积累了相当丰富的资料。但与中-酸性岩有关的夕卡岩型和热液型金属矿床成矿作用中铂族元素的地球化学方面研究却很少。
On the basis of a geological survey and chemical analyses of some 12 types of mineral assemblage from 15 copper deposits in a certain district in China, the authors have come to the following conclusions:1. The distribution and enrichment of precious metals are closely related to genetic type, mineral and element assemblages of the copper deposits. Precious me-tals in the district studied occur preferentially in skarns, hypothermal and mesother-mal copper deposits, whose ore-forming materials are all thought to be of deeper origin.2. Geochemically, the behavior of precious metals in these copper deposits has the following features:(1) Their contents are normally low in copper ores and sulfides, a strong in-dication of the dispersion and chalcophile character of the precious metals.(2) Most strongly concentrated are gold, platinum and palladium. The order of enrichment is Au > Pt > Pd.(3) An intimate relationship between palladium and gold is observed. The ratio of gold to palladium is 100 : 1. Platinum shows a remarkable siderophile trend, its content is higher than that of palladium. The ratio of platinum to palladium is 2 : 1.3. Mineral assemblages rich in precious metals in this district include: bornite-chalcopyrite, chalcopyrite-magnetite, molybdenite-chalcopyrite. Precious-metal-rich sul-fides are chalcopyrite, bornite, molybdenite and arsenopyrite.4. Precious metals are largely enriched in high temperature ores in pneumatoly-tic-hydothermal stages during the later periods of the metasomatic process between acid-intermediate magmatic rocks (granodiorite, quartz-diorite) and carbonate rocks. Most of the gold, platinum and palladium are associated with high temperature ores (300-500℃).5. Two different manners of occurrence have beeen recognized of the precious metals in copper ores and sulfides: as precious metal minerals (native gold, silver-bearing native gold, palladium-bearing electrum and kustelite), or being dispersed in various minerals in copper ores. The mineral system of Au-Ag may be considered as a geothermoineter. It is noted in this district that native gold and electrum are found associated with high temperature ores exclusively, whereas kustelite is present in medium-low temperature (100-300℃) ores.
出处
《地球化学》
CAS
1974年第3期157-168,共12页
Geochimica
