Discriminant Model of River-Lake Facies in the Upper Reach of Hanjiang Section of Jianghan Basin Based on Fisher Principle

In order to explore the practicality of the Fisher model in the Quaternary river-lake evolution of the basin, in this paper it takes the particle size data and sedimentary facies of a single borehole in the upper reach of the Hanjiang River in the Jianghan basin as the training samples of the model, which is calculated by Fisher's basic principle. Then the river-lake phase discrimination model is used to analyze the sedimentary environment evolution of the study area by using the model discrimination results. According to the one-way variance and the significance analysis results, the Fisher model has a good distinguishing effect on the river phase, the river-lake transition phase, and the lake phase. The leave-one-out-cross-validation result reaches 80.6%, exceeding the 75% standard required for the discriminant model application. At the same time, the results of the quantitative evaluation of porous sedimentary facies are compared with the qualitative classification results, and the comprehensive coincidence rate reaches 85.06%, which further verifies the practicality of the Fisher model in the identification of rivers and lakes. According to the results of discriminant analysis, since the Early Pleistocene, there are four large sedimentary cycles in the study area, which can be divided into eight sedimentary stages. The hydrodynamic sources are complex and changing rapidly in different sedimentary stages, and the regional sedimentary environment evolution and Neotectonic movement are consistent. This study demonstrates that it is feasible to establish Fisher model based on particle size data for analyzing sedimentary facies and sedimentary environment, and enrich the sedimentary environment data of Hanjiang Section of Jianghan basin. It provides an important reference for basin water resources investigation and protection.