Abstract:

The Yellow River Delta is one of the most famous river deltas in the world. Since Xue and Cheng (1989) first systematically proposed the spatio-temporal distribution of ten Holocene superlobes in the delta, this hypothesis remains unchanged in the last three decades. To redefine the characteristics of sedimentary evolution and spatial-temporal distribution of Lijin superlobe in the Yellow River Delta, 4 boreholes with a length of 20-30 m were obtained in the coastal plain of South Bohai Bay. Combined with the achievements of previous boreholes in the study area, the stratigraphical data and AMS¹⁴C dating results in these boreholes revealed that the river channel and flooding plain dominated the study area in the early Holocene. It turned to be saltmarsh, tidal flat and shallow sea environments in the chronological order when the Holocene transgression reached the study area. Delta progradation began as the sea level decelerated, and was finally capped by the terrestrial sediments in this area. The ancient river channel of the Yellow River might enter the sea by the southern area of Huanghua during 9000-8000 cal a BP. After ~8000 cal a BP, the main river channel shifted southward between Binzhou and Huiming, which led to the development of Lijin superlobe from 7000 cal a BP to 5500 cal a BP. The northern boundary of Lijin superlobe may link Mashanzi with Yangxin while the southern one was located between Guojingzi and Mihe River. The ancient Yellow River mouth might return to Huanghua after ~5500 cal a BP and formed the Huanghua superlobe ranging from 5500 cal a BP to 3500 cal a BP. The Yellow River changed its main course to Tianjin earlier than 3500 cal a BP and might turn back to Qikou in Hebei province after ~700 BC.

Key words: Yellow River Delta, superlobe, shifting of river channel, chenier, sedimentary evolution