北祁连中段北坡铀矿地质特征

GEOLOGICAL FEATURES OF URANIUM MINERALIZATION IN THE NORTHERN SLOPE OF THE MIDDLE SECTOR OF NORTH QILIAN MOUNTAINS

北祁连中段北坡是甘肃西部的一个铀成矿带,下奥陶统火山岩、下志留统条带状砂岩及硅质岩、上泥盆统块状砾岩和含砾砂岩是重要的含铀建造;矿化受断裂和裂隙构造控制,区域性NW向构造岩浆岩带控制着矿带的延展方向,矿体产于多次活动的断裂构造带中;矿化与岩体有密切的时空关系,许多矿点和矿化点围绕岩体分布或产于岩体内部,晚加里东-晚燕山期的火山-次火山中酸性岩浆活动引起和促进了含铀建造中铀的活化、迁移和富集;铀矿化是地层、构造和岩浆活动共同作用的结果,矿化类型属于钠交代热液型。

The northern slope of the middle sector of North Qilian Mountains is an uranium ore belt in the west Gansu province. Lower Ordovician volcanics, Lower Silurian banded sandstone and siliceous sandstone and Upper Devonian massive conglomerate and pebble-sandstone are the important U-bearing formation. The mineralization is controlled by faults and cracks, extension of the ore belt by the regional NW tectonomagmatic rock belt. Ore bodies occur generally in the multiply active fractural zones. The mineralization is closely related to intrusive body temporally and spatially so as to many ore （mineralization） occurrences which are located in the intrusive body or in the surroundings. Late Caledonian-Late Yanshanian volcanic-sub-volcanic intermediate-acidic magmatism played an important role in mobilization, transportation and enrichment of uranium form the formation. U-mineralization is the result of combination of the strata, tectonism and magmatism thus the Na replacement hydrothermal type.