Late Holocene palaeoflood events and its climatic background in the Yanwan reach of the Shahe River,Huaihe River basin
Palaeoflood events are instantaneous responses of hydrological processes to extreme climate.Through field investigation,a loess-paleosol sedimentary profile containing a set of overbank flood deposits(OFD1,OFD2 and OFD3)that recorded the extraordinary palaeoflood events was found on the platform scarp of the Shahe River,a tributary of the Huaihe River.The sediment samples were collected,and the physical and chemical properties and optically stimulated luminescence(OSL)dating were analyzed.The results showed that the end-members analysis of particle size indicated that OFD 1,OFD2,and OFD3 were overbank flood deposits affected by hydrodynamic forces.However,the particle size composition of OFD3 and OFD1 primarily consisted of sand(＞60％),while the particle size composition of OFD2,S0,Lt and L,was mainly silt(＞70％).The magnetic susceptibility values of OFD3 and OFD1 were significantly higher than those of S0,L,and L1;and the contents of Na2O,K2O and SiO2 were higher,while the contents of Al2O3and Fe2O3 were lower in OFD3 and OFD1.The particle size composition,magnetic susceptibility value and geochemical element composition of OFD2 were similar to those of S0,L1 and L1,but significantly different from those of OFD1 and OFD3.These differences could be attributed to the varying material sources of OFD2,OFD3,and OFD1.OSL dating and a stratigraphic chronological framework of sedimentary profile indicated that the three extraordinary palaeoflood events were recorded during the late Holocene from 1550 to 1400 a BP in the Huaihe River basin.The analysis of high-resolution climate proxy indicators,atmospheric circulation factors,and global mean temperature demonstrated that the extreme flood events that occurred during the late Holocene from 1550 to 1400 a BP were a direct response to the abrupt climate changes,corresponding to the severe climate deterioration period of the Northern and Southern Dynasties in China.These findings are significant in understanding the regional response of hydrological climate change to global change.
palaeoflood eventsidentificationchronologyclimate backgroundHuaihe River basin
万方数据
维普
