The Formation And Evolution Of The Delta In Minjiang Estuary

Based on extensive collection of former data, investigation in situationand laboratory analyses, through the systematic analyses about the environment factors,geomorphological characteristics, sedimentary characteristics and environment evolution,the thesis discusses the formation and evolution of underwater delta in MinjiangEstuary.Firstly the thesis analyzes environment factors including the pattern of geologicstructure and sea-level changes, river hydrology and sediment, marine hydrology,which control or affect the formation of underwater delta .It also discusses itsgeomorphological characteristics,origin and evolution concerning underwater deltaplain,delta front and fore-delta, based on the underwater topography and sedimentarycharacteristics that are concluded from the data of subbottom profile and side - scansonar in Minjiang Estuary. Furthermore, it discusses recent and modern sedimentarycharacteristics and environment of underwater delta according to the distribution ofsurface sedimentary types,correspondence analyses of granulometricparameters,subbottom structure and comparisons of columnar samples, syntheticallyanalyzes its sedimentary characteristics and environment and reveals its evolution sincelate Pleistocene, according to the data of geologic cores and seismic reflection sections inthese areas .After synthesizing these studied results, the thesis reveals the evolutionlaws of underwater delta in Minjiang Estuary and proposes the countermeasures ofsynthetical harnessing project of shipping channels.