Shek Mun Bay, the Northwestern Margin of Yangtze Block Discovery of Lead-Zinc

The lead-zinc mine in Shimenwan, Ziyang county is situated in the active continental margin of northwestern Yangtze Block,with the tectonic setting of Paleozoic back-arc basin. Lying between the large lead-zinc metallogenic belt in Mayuan area and that in Chaoyang, Zhuxi County, Hubei Province, the mine is attracting more and more attention. By surface recourse and engineering control, 6 belts of lead-zinc ore body were delineated. Being stratiform and lenticular, the ore body is 72-292 m long and 0.78-4.06 m thick. The average grade of Pb concentration is 1.47%-2.83% and the average grade of Zn is 2.38%-8.45%. Formed in the dolostone in upper second lithologic section of upper Sinian series, the occurrence of ore body is consistent with that of stratum, and is controlled by a group of bedding fault fractured zone. It is considered that the trace elements in the ore comes from the metallogenic surrounding rock, the premitive Pb is largely from the crust-mantle orogenic belt. The lead-zinc mine in Shimenwan is realted to sedimentation, and experienced different degrees of reformation later. The genetic type of studied lead-zinc mine is therefore regarded as reformed sedimentary deposit.