The application of end - member analysis in identification of paleo - floods in Wuhan section of the Yangtze river

Abstract

The end-member modeling analysis can extract the end-members representing different sedimentary dynamic processes from the sediments with complex particle size distribution characteristics, revealing the paleo-flood period in the middle reaches of the Yangtze River. Taking the representative Quaternary sediments of the ZK145 bore¬hole in the lake behind the Yangtze River’s natural embankment as an example, the eigenvector rotation algorithm was used to analyze the end-member modeling of the borehole grain data. The study shows that four end-members with geological significance can be isolated: EM1 represents river alluvial sand; EM2 represents fine sand with through which water flows; EM3 and EM4 represent hydrostatic lake sedimentation. Using the content of coarse-grained end- members (EM1, EM2) in the borehole combined with the magnetic susceptibility index, 9 paleo-floods were identi¬fied in the lacustrine sedimentary stage. The end-member analysis provides new methods and new ideas for the study of lacustrine paleo-floods after the Yangtze River embankment and, at the same time, created conditions for the inver¬sion of paleo-floods.