华北地台区太古界含铁岩系中铀矿床的成矿地质条件

GEOLOGICAL CONDITION OF U-DEPOSITS WITHIN THE IRON-BEARING ROCKS OF ARCHEAN IN THE NORTH CHINA PLATFORM

U-deposits occurring in the iron-bearing rocks of Archean in the North China Platform belong to U-Fe-Type U-deposits. They are located in the iron ore deposits in stable blocks where sub-tectonic units, hydrothermal activity and green-altered rocks are developed. Mineralization is usually in the altered rock belts near to the rich iron ore bodies or in the contact zones between granitic-migmatitic gneiss and banded Fe-quartzite. Metallogeny is related to the late hydrothermal activity during regional metamorphism and super-metamorphism. Uranium is derived from the original sedimenary rocks and concentrated to form ore during the time when the sedimentary rocks were exposed to super-metamorphism. U-ore and rich iron ore are the different-staged products of one geological process.Age of the U-deposits is 1907 ± 35 Ma aproximate to the rich iron ore which is closely related to green-altered rocks.