Characteristics of sedimentary environment since Quaternary in northern Jianghan Basin, China: Reconstruction of paleoenvironments

Abstract

Reconstruction of sedimentary evolution plays a significant role in the investigation of natural groundwater contamination and stratigraphic mineral resources. In this paper, the variation in sedimentary characteristics and sedimentary evolution were studied by lithology, chronology and organic matter with the high-resolution grain size parameters of boreholes for Quaternary in northern Jianghan Basin. Following more traditional plotting of grain size parameters and summary statistics, visual categorization and analysis of grain size frequency distribution curves provided an effective measure for the identification of sedimentary facies. Combining with the Fisher model, new and highly efficient discriminant formulas were established, and tested for the validity. Additionally, the sedimentary evolution process and the provenance of different sedimentary facies were identified with the help of organic matter and δ13Corg data, provided geological information to explore the natural contamination of reducing arsenic ions and excessive nitrate in strata. The identification results suggest that fluvial and lacustrine sediments are dominant in the area, and the regional sedimentary environment is uniform and not affected by the transgression. The analysis results of grain size with organic matter parameters are consistent for discriminating sedimentary facies, which verified the rationality of grain size analysis and confirmed the use of organic matter content to be effective in identifying the process of fluvial and lacustrine sediments. Based on the chronological results of Optically Stimulated Luminescence dating and sedimentary facies determination, the sedimentary evolutionary process was deduced during the Quaternary for the study area. This research has important significance for the division and correlation of Quaternary borehole strata, underground contamination study, as well as environmental planning and protection.