我国东部地区产于碳酸盐岩中层控铅锌矿床的区域地质特点

产于碳酸盐岩中的层控铅锌矿床是世界上铅锌金属的主要来源。我国东部地区碳酸盐岩中层控铅锌矿床的赋存层位很多,从元古界到中生界均有发现。但较为重要的矿化层位为数并不太多,它们在空间上的分布与区域地质构造演化有十分密切的关系。

Regional Geologic Setting Of The Stratabound Lead-Zinc Deposits In Carbonate Rocks Of East China

In East China, there are plenty of carbonate strata where stratabound lead-zinc deposits occur. The most significant mineralized stratigraphic units are Proterozoic Liaohe Group and lower part of Changcheng System (formerly Nankou System), Sinian Dengying Formation and Lower Carubrian Qingxudong Formation of Lower Paleozoic era, as well as Middle and Upper Devonian rocks of Upper Paleozoic era. Occurring in clusters and in zones, these deposits are distributed primarily on platforms and secondarily in geosynclinal areas and can be assigned to four metallogenic belts, i.e., Sichuan-Yunnan, Hunan-Guizhou, Hunan-Guangxi-Guangdong, and Gansu-Shanxi. The first belt is located on the flank of the marginal island arc fold system of the Yangtze massif; the second and the third one lie in the depression basin formed as a result of minute expansion between island arc fold systems of different ages in south China; the last one is sihiated iii the geosynclinal belt between the Yangtze massif and the Sino-Korea massif. Among quite a lot of mineralized strata in metallogenic belts of the platform area, the main stratigraphic units invariably occur in the first stable or metastable carbonate formation-especially in bottom or top of this formation-formed after the orogeny that resulted in the transformation of the area to the platform phase, thus constituting a section pattern in normal or reverse order In geosynclinal area, however, the major ore-bearing units are mostly found in the flysch formation. Mineralized strata are lithologically highly porous carbonate rocks with good permeability, which might be classified into the following types in accordance with their respective paleogeographic locations. Ghiaracterized by polystage activities, the deep-seated fracture zones have an obvious spatial connection with the known metallogenic belts; they seem to have had a direct bearing on the lithofacies and paleogeographic distribution during the sedimentation of ore-controlling strata, and their late-stage activities must have much to do with the epigenetic enrichment of ores.