1296 / 2024-09-20 23:11:09

Landscape evolution and human activities in the lower Yellow River revealed by core chronologies

OSL,floodplain,Holocene lakes,the lower Yellow River avulsion,southwest Shandong Plain,human activities

Session 27 - Coastal environment evolution : from the past to the future

Floodplain in river lower reaches is one of the most dynamic places, which is continuously changing its shape and structure controlled by the balance among sea-level, sediment supply, accommodation space and human activities. The evolution of the lower Yellow Rive Plain has witnessed the shaping influence of these factors, with Yellow River channel migrates between the North China Plain (northern path) and Huaibei Plain (southern path). This study investigated the formation and transformation of fluvial and lacustrine systems along the southern path and their implications for the pattern of archaeological sites distribution (human activities). We collected 16 OSL samples from the upper 10 meters of core JZK05 (total depth of 130 m) in Jining, southwest Shandong Province, and constructed a chronological framework. The OSL ages ranged from >123 ± 12 ka to 0.14 ± 0.01 ka, revealing three significant hiatuses with age gaps at 0.40–1.53 ka, 2.29–4.75 ka, and 5.39–47.7 ka. Pre-Holocene sediments consist of hard clay with silt, presented in both interfluve and incised valley formed during low-stand sea level. Holocene sediments, identified above 5.89 m, dated back to ca. 5.39 ka. During the Holocene, the southwest Shandong region experienced alternating floodplain and lacustrine environments, driven by Yellow River avulsion and channel migration. The formation of Holocene lakes in the southwest Shandong Plain occurred in three stages: the earliest lakes developed at around 4 ka in the western part, near the Yellow River alluvial fan, followed by lakes formed at ca. 2-2.5 ka near the Nansi Lake area, and the most recent phase of lake development at ca. 1 ka distributed throughout the region. The frequent avulsions and floods of the Yellow River were the primary drivers of lake formation and contributed to the decline of local civilizations and prompted population migrations.