Study On The Mixed Sediments In Ordovician The Lower Paleozoic In Bohai Bay Area

Mixed sedimentary phenomenon in the Bohai Bay Basin transitional environment has attracted researchers' value. Mixed sedimentary phenomena is described for terrigenous clastic rocks and carbonate rocks mixed into rocks or strata on the composition and structure, this deposition phenomenon was not concerned in the past. Domestic and foreign scholars tend to terrigenous clastic rock and carbonate rock as two separate research units. In recent years, some researchers started to make the analysis of the definition and classification of mixed sediments. In this paper on the basis of previous research, comprehensive utilization of regional geological data, logging data, and geological profile data, Sedimentology and Vail sequence stratigraphy theory as the instruction, the sequence division was divided into 2 super and 11 secondary sequences, and then set up 6 sequence frameworks. Under the frameworks, explore the phenomenon of Ordovician terrigenous clastic rocks and carbonate rocks mixed into rocks or strata in Bohai Bay transitional environment. Results show open platform environment mainly composed of carbonate rocks, mixed sediments is mainly Carbonate- Mixed rocks and Mixed rock series, forming process is gradual. Near the ancient continental margin, terrigenous clastic composition increase, mixed deposits mainly be terrigenous clastic rocks- mixed sedimentary strata, and forming process is abrupt changing. On this basis, analyzing the ancient landform in the Bohai Bay area, summarize plane distribution and space distribution of mixed deposition by stratigraphic correlation and multistage sequence analysis. It shows that Hebei and Shangdong primarily be maxed open platform with part maxed shallow. Henan primarily be maxed restricted platform and maxed tidal flat. Most of Shangxi is maxed tidal flat. Different cycle times have different facies distribution.