长江中下游及邻区水系沉积物和岩石铜元素分布特征及铜地球化学省成因研究

Distribution of Copper in Stream Sediments and Rocks and Genesis of Copper Geochemical Provinces in the Middle and Lower Reaches of the Yangtze River and its Adjacent Areas,China

利用水系沉积物地球化学数据,以Cu含量大于32×10^(-6)为边界在长江中下游及邻区圈定出面积大于1000km^(2)的铜地球化学省6个。为识别该区铜地球化学省的成因,对水系沉积物和岩石中Cu的分布特征以及铜地球化学省与矿集区的空间对应关系进行了剖析。结果表明,铜矿集区往往产出于具有3层套合结构的铜地球化学省内部,铜矿集区与铜地球化学省的浓集中心存在空间对应关系。研究区铜地球化学省主要包括三种成因类型,分别为:由成矿作用及后期的风化分散作用引起、由高背景地层引起和由高背景地层和成矿作用及后期风化分散作用共同引起。该认识对于缩小找矿靶区,提高找矿精度和效率起到较大的促进作用。

Six copper geochemical provinces,each with area of over 1000 km^(2),are delineated in the Middle and Lower Reaches of the Yangtze River and its adjacent areas on the basis of a threshold value of 32×10^(-6)for the stream sediments.To reveal the genesis of the copper geochemical provinces in this region,the distribution of copper in stream sediments and rocks as well as the spatial relationship between the copper geochemical provinces and ore districts were analyzed.The copper ore districts usually occur within the copper geochemical provinces with a three-layered structure,and the copper ore districts are situated in the concentrated center of the copper geochemical provinces.There are three genetic types of the copper geochemical provinces in the study area,which are caused by(1)mineralization and later weathering and dispersion,(2)strata with high copper background values,and(3)strata with high copper background values and mineralization and later weathering and dispersion.This understanding is useful in narrowing the prospecting target area and improving the accuracy and efficiency of prospecting.