Luminescence dating of core sediments from Jining of Shandong Province in the lower Yellow River Plain and its geomorphological implications

Abstract

The Yellow River is the primary force shaping the landscape of the North China Plain. Historically, the river main channel migrated to northern and southern directions alternatively, divided by the central Shandong Mountains. Previous sedimentological and chronological studies have mainly concentrated on the areas to the northern of the Yellow River, and are scarce in the southern areas. The Jining area in the southwest Shandong Plain, part of southward migration area, and its sedimentology was characterized by frequent floodings and lakes during the Holocene, whose landforms had been dramatically altered by avulsions of the Yellow River. Studies using drilling cores have mainly focused on regional geological and stratigraphic surveys, with very limited chronological data, which impeded the understanding of geomorphic evolution and the Yellow River avulsion. In this study, 16 optically stimulated luminescence (OSL) samples were collected from the upper 10 m of core JZK05 (130 m in depth) to establish a chronological framework using quartz OSL dating method. Results indicated that the OSL ages ranged from >123 ± 12 ka to 0.14 ± 0.01 ka, and revealed three sedimentary hiatuses at age gaps of 0.48–1.31 ka, 2.66–4.41 ka, to 5.20–47.7 ka, respectively. The earliest sedimentary hiatus was caused by headward erosion during low sea level, and the other two were inferred to be related to the diversions of the Yellow River. The Holocene sediments, beginning at approximately 5.2 ka, exhibited episodic accumulation patterns with frequent transitions between flood and lacustrine facies. The formation of lakes occurred in three main phases: around 4 ka, 2–2.5 ka, and 1 ka, closely linked to the Yellow River diversions and floodings. Our dating results indicated that caution should be taken when reconstructing paleoenvironment using proxies without corresponding high-resolution age control, as sediment accumulation in floodplains often occurred as episodic events, not continuous. These findings provide insights into the interplay between natural flooding events and climate changes in shaping the region's landscape.