中国铜的区域成矿地球化学分布模式与找矿预测

Regional metallogenetic geochemical distribution models and prospecting prediction of copper in China

中国1∶20(25)万区域地球化学调查工作已完成620余万km2,覆盖了全国大部分可扫面积,获得了海量高质量基础地球化学数据和数以万计的地球化学异常,在地质找矿中发挥了巨大的作用,但对这些资料的开发利用仍是当前的一个重要课题。通过对以全国1∶200 000区域地球化学调查资料为基础编制的中国1∶500万Cu地球化学图的研究表明,不同大地构造单元Cu地球化学背景差异明显,具有不同的特征;地球化学景观不同,Cu地球化学背景值明显不同,以岩溶景观区Cu背景值最高而森林景观区最低;不同景观类型、不同矿床成因和不同出露条件下铜矿的区域异常规模和异常强度差异很大;中国Cu的区域成矿地球化学模式可概括为成矿作用与地球化学省相关,以及成矿作用与地球化学省无明显关系两种,并且在高、低背景区或甚低背景区中Cu异常的分布特征不同,Cu的成矿地球化学特征也不同。在全国范围内圈出79个Cu地球化学省和1个地球化学域,并以地球化学省为基础,结合大地构造分区和已知矿床的分布及地质背景,划分出20个Cu找矿远景区。

More than 6200thousand square kilometers of regional geochemical surveys at a scale of 1∶200000or 1∶250000have been carried out in China,covering most of the feasible areas in the mainland.Enormous basic high quality geochemical data and tens of thousands of geochemical anomalies obtained have played a huge role in geological prospecting;nevertheless,further development and utilization on these data is still an important topic at present.Based on the copper geochemical map of China at the scale of 1∶5000000,which was compiled using the regional geochemical survey data with the scale of 1∶200000,it is indicated that the copper geochemical background of different tectonic units is of great variety.The Cu geochemical background values are significantly diverse from each other for various geochemical landscapes,showing the highest-level in Karst landscape but the lowest in Forest landscape.The distinctions between the dimension and intensity of regional anomalies under different types of landscapes,metallogenesis and outcrop conditions are significantly evident.Two regional metalogenetic geochemical patterns of copper in China can be summarized into two cases,one is that the Cu mineralization is related to the geochemical province while the second is that there is no evident relationship between Cu mineralization and the geochemical province.Moreover,in high and low or very low Cu background areas the distribution of Cu anomalies are different,and the regional metallogenic geochemical characteristics of Cu can be differ obviously.In the mainland some 79Cu geochemical provinces and one geochemical domain have been delineated and 20Cu ore prospecting areas are divided on the basis of the geochemical provinces,tectonic divisions and the distribution as well as the geological background of known ore deposits.