试论湖南衡阳盆地与地幔柱的关系及其对关键矿产深部探测的意义

Discussion on the relationship between Hengyang basin and mantle plume and its implication for the deep prospecting of key minerals

衡阳盆地是华南地区独具特色的中—新生代陆相沉积盆地,其形成机制与丰富的矿产资源都十分引人注目。衡阳盆地近等轴形态,地形上表现为典型的"盆山体系",重力资料显示出地幔隆起的特征,构造形式上发育"棋盘状"和"环形(弧形)"格局,火成岩与成矿元素组合以及同位素特征均具有幔源特征,这表明衡阳盆地的形成与华南地区中生代地幔柱活动之间具有密切的成因联系。盆地及其周缘矿产资源具有长时期、多矿种、强富集的特征。不同时代和不同矿种组合的成矿作用与区域岩浆作用和盆地沉积作用具有明显的专属性。衡阳盆地及周边不但出现了丰富的有色金属和非金属矿产,也出现了钨锡铌钽铋碲铀等关键矿产,但后者的工作程度最低。因此,在深部矿产探测过程中应做到"四注意四加强"。

Hengyang Basin,one of the unique Mesozoic-Cenozoic continental sedimentary basin in south China, has drawn a lot of attention on the aspect of the special formation mechanism and highly concentrated mineral resources. The terrain of Hengyang Basin is characterized by typical "Mountain-Basin System". The regional gravity data show the characteristics of mantle uplift in Hengyang Basin. There are several deep faults intersect each other in EW, NW and NE direction, and a typical "arc structure" pattern. Moreover, the characteristics of igneous rocks and metallogenic element assemblage and isotope composition suggest a mantle origin. The properties show that the formation of the Hengyang Basin is genetically related to Mesozoic mantle plume of south China. The mineral resources in the Hengyang Basin and its surroundings are characterized by multiple minerals and intense enrichment. We found that the metallogenic age of Hengyang Basin span a long period of time dominated by the Meso-Cenozoic. The different ages mineralization and mineral assemblages have obvious specificity with regional magmatism and basin sedimentation. Hengyang basin and the surrounding areas are not only rich in non-ferrous metals and non-metallic minerals, but also key minerals such as W, Sn, Nb Ta, Bi, Te, U, etc. However, the least studied have been carried out in Hengyang Basin. Therefore, in the process of deep prospecting exploration, there are "four points of attention, four points of strengthening" should be paid more attention.