Petrology and sedimentary environments of the Hongshuizhuang Formation in the Kuancheng region, Hebei

The carbonate tidal-flat deposits in the Jixianian Hongshuizhuang Formation in the Kuancheng region, Hebei are made up of dominant grayish black shales with pyrite nodules and medium-to thin-bedded muddy dolostones in the lower part, and the silt-bearing muddy laminated dolostones, sand-bearing dolostones and manganese-bearing micritic dolostones in the upper part of the measured section in this study. This succession of strata consists dominantly of dolostones and shales. The former may be subdivided into siliceous dolostones,(siltbearing) muddy (sandy) dolostones, and (manganese-bearing) micritic dolostones while the latter comprise siliceous shales and dark shales. Three types of sedimentary environments are identified, including supratidal, intertidal (upper and lower) and subtidal (upper and lower) zones on the basis of petrological features and sedimentary structures. The Hongshuizhuang Formation oppears as organic matler-rich (algae and sapropelic fragments) excellent source rocks, and constitutes the favourable source-reservoir-seal disposition together with the overlying Jixianian Tieling Formation and Qingbaikouan Xiamaling Formation, which must be considered highly prospective for the petroleum exploration.