Metallogenic geological background of lead-zinc polymetallic deposits of Sinian Dengying Formation in the northwestern margin of Yangtze landmass

According to the train of thought “structure controls basin, basin controls facies and facies controls ore deposit”, the authors studied metallogenic conditions of lead-zinc deposits such as sedimentary basin, ore-bearing formation, ore-controlling structure, lithofacies and paleogeography, analyzed metallogenic characteristics and summed up the ore-forming regularity. In Dengying period, NE- and NNE-trending contemporaneous faults were developed on the Chuanxi-style basement in the northwest margin of Yangtze plate and, as a result, nearly NE-trending second-order basins and platforms were formed, which constituted the structural framework. of the platform alternate with the basin. The second-order basin was characterized by infratidal zone sediments of restricted basin, slump dolorudite appeared on the marginal slope of the platform, and ore-bearing hydrothermal fluids that migrated along contemporaneous faults were concentrated in brecciform marble to form ore deposits. Studies show that lead-zinc mineralization of Dengying Formation was obviously controlled by such factors as semi-active type basement of the basin, second-order basins in magnesian carbonate rock platform and contemporaneous faults that control the second-order basin.