Paleo-fluvial sedimentation on the outer shelf of the East China Sea during the last glacial maximum

摘要

Evidence from lithology,foraminiferal assemblages,and high-resolution X-ray fluorescence scanning data of core SFK-1 indicates tidally influenced paleo-fluvial sedimentation during the last glacial maximum (LGM) on the outer shelf of the East China Sea.The paleo-fluvial deposits consist of river channel facies and estuarine incised-valley-filling facies.Different reflections on the seismic profile across core SFK-1 suggest that the river channels shifted and overlapped.River channel deposition formed early in the LGM when sea level fell and the estuary extended to the outer shelf.Channel sediments are yellowish-brown in color and rich in foraminifera and shell fragments owing to the strong tidal influence.Following the LGM,the paleo-river mouth retreated and regressive deposition of estuarine and incised-valley-filling facies with an erosion base occurred.The river channel facies and estuarine incised-valley-filling facies have clearly different sedimentary characteristics and provenances.The depositional environment of the paleo-river system on the wide shelf was reconstructed from the foraminiferal assemblages,CaCO3 content and Ca/Ti ratio.The main results of this study provide further substantial constraints on the recognition of late Quaternary stratigraphy and land-sea interactions on the ECS shelf.