摘要:
冀北地区是火山岩型铀矿的产出远景区,以该区1∶20万水系沉积物及区域岩石资料为基础,探讨了冀北地区铀的时空分布特征,目的是为本区的铀矿勘查提供地球化学依据.从空间分布上看,内蒙古华力西晚期褶皱带及内蒙地轴铀含量较富集,铀地球化学异常呈北东向带状分布于崇礼石窑子-丰宁森吉图,向东北延伸至围场老窝铺-姜家店一线,与沽源-红山子成矿带南段分布范围相一致.铀地球化学异常的形成受区内燕山期中酸性岩体、白垩系张家口组及大北沟组地层、北东向断裂构造、火山盆地等地质因素的联合控制,与铀矿关系密切,现已发现的几个铀矿床都位于铀异常带上,因此铀异常可以作为铀矿的找矿标志.从时间分布上看,地层及岩体存在较一致特征,随地质体时代从老到新,铀含量有逐渐增大的趋势,太古宇及元古宇铀含量低,上侏罗-下白垩统铀含量高.
Abstract:
Northern Hebei Province is a prospective area of volcanic rock-hosted uranium deposits.Based on the 1∶200 000 stream sediment and regional rock data, this paper discusses the spatial and temporal distribution of U in northern Hebei Province in order to provide geochemical information for uranium exploration.In spatial distribution, the high background values of uranium are distributed in the late Variscan folded zone in Inner Mongolia and Inner Mongolia axis, and are focused on the zone of Shiyaozi in Chongli County-Senjitu in Fengning County-north Guyuan County-north Weichang County.Uranium geochemical abnormal belt corresponds with the south of the Hongshanzi metallogenic belt.The formation of U geochemical anomaly is controlled by geological bodies which are intermediate-acid rock mass of Yanshanian epoch and acid volcanic rock of Zhangjiakou strata and Dabeigou strata, NE-trending faults and volcanic basins.Uranium geochemical anomalies are closely related to uranium deposits.Uranium deposits are located along the uranium anomaly belt, and hence uranium anomalies can be used as uranium ore prospecting indicators.In temporal distribution, U values have a tendency to increase and are enriched in late Jurassic and early Cretaceous strata, but are low in Archean and Proterozoic strata.
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