华南陆块铜的地球化学块体与成矿省的关系

在区域化探全国扫面计划1∶20万水系沉积物样品Cu含量的基础上,描述了华南陆块铜地球化学块体的空间分布特征,并分析了它们与地质体、已知的铜成矿省(矿集区)在空间上的对应关系。发现华南陆块的铜地球化学块体主要分布于扬子地块西南缘,长江中下游、西秦岭、三江地区和湘粤桂交界区。其中扬子地块西南缘铜地球化学块体主要与峨眉山玄武岩的铜高背景值有关,其他异常与海西期镁铁质-超镁铁质岩有关的铜矿和层控型铜矿有关;长江中下游地球化学块体与长江中下游成矿带吻合;西秦岭铜地球化学块体与岩体、铜矿和以铜为伴生元素的矿床有关;三江、湘粤桂交界区的铜地球化学块体也有与之对应的铜矿床或铜为伴生元素的矿床。通过这些地球化学块体与已知的地质体、成矿省(矿集区)的对比得出如下结论,铜地球化学块体的形成可能与岩石的高背景值、铜成矿省(矿集区)或铜为伴生元素的矿床有关。巨量的成矿物质的供应只是形成大型、超大型矿床的必要条件,如长江中下游铜地球化学块体为铜成矿省提供物质来源;但每个地球化学块体并不一定都有与之对应的矿集区,如峨眉山玄武岩铜地球化学块体与玄武岩高背景值有关,并没有形成大型的铜矿床。

Relationship of copper geochemical blocks and metallogenic provinces in South China Continent

Based on the 1∶200000 stream sediments data from Regional Geochemistry-National Reconnaissance(RGNR) Project in South China Continent,this paper described the spatial distribution of copper geochemical blocks,and studied their relationship with geologic bodies and metallogenic provinces.It was found that copper geochemical blocks in South China Continent are mainly distributed in the southwestern margin of Yangtze Block,the middle and lower reaches of the Yangtze River,West Qinling,the Jinshajiang-Lancangjiang-Nujiang Rivers and the border area of Hunan,Guangdong and Guangxi Provinces.The geochemical block in southwestern margin of Yangtze River is largely due to high background copper value in Emeishan basalt.The rest is consistent with the copper deposits related to Hercynian mafic-ultramafic rocks and strata bound type copper deposits.The geochemical block in the middle and lower reaches of the Yangtze River coincides with its mineralization belt.The geochemical block in West Qinling area is concerned with magmatic rocks,copper and other metal deposits.Many copper ores and metal deposits are distributed in the geochemical blocks of Jinshajiang-Lancangjiang-Nujiang Rivers,and the border area of Hunan,Guangdong and Guangxi Provinces.The conclusion was drawn that copper geochemical block is related to high background copper value in rocks,metallogenic provinces or other deposits,in which copper acts as an accompanying element.The supply of huge metallogenic materials is basic for forming large ore deposits,such as in the middle and lower reaches of the Yangtze River,where copper geochemical block provides metallogenic materials for forming copper deposits.However,not each geochemical block results in metallogenic province,like the geochemical block in Emeishan basalt.