Luminescence dating of core sediments from the southern coastal Bohai Sea, China, and its implications for transgression history during the Late Quaternary

Zhiqiang Xu¹Yang Han¹Bingpeng Yan¹Mingbo Li¹Ruolin Jiang²Ruonan Tian²Bohui Liu²Zihui Zhu¹Weitao Yuan^3*Zhongping Lai²

• ¹Shandong Provincial No. 4 Institute of Geological and Mineral Survey, Weifang, Shandong Province, China
• ²Guangdong Provincial Key Laboratory of the Marine Disaster Prediction and Prevention, Shantou University, Shantou, Guangdong Province, China
• ³Weifang University, Weifang, China

Several marine strata have developed along the southern coastal Bohai Sea since the Late Quaternary, preserving abundant records of sedimentary evolution. This region is ideal for studying the sedimentary history of a river-sea interaction area. However, detailed sedimentological and chronological studies remain limited, mainly focusing on the estuaries of the Mihe River. In this study, 12 optically stimulated luminescence (OSL) samples were collected from the upper 20 m of a 101 m core to establish a chronological framework using quartz OSL dating. Grain-size analysis was also conducted to determine sedimentological characteristics. Results indicate that the quartz OSL ages range from >100 ka to 6.2 ± 0.4 ka, and we believe they were the minimum ages when equivalent dose (De) >ca. 250 Gy (sample DZK3-G07 and below) owing to OSL signal saturation. Our findings reveal a sedimentary hiatus between >100 ka and19.8 ka. Holocene sediments are found above a depth of 8.4 m with an onset age of approximately 10.5 ka. A lacustrine layer (8.4-9.6 m) in core DZK3 was dated to 19.8-10.5 ka, which is much older than that of the limnetic and lagoon layers in other cores in this area. The lacustrine facies likely originated from a small water storage depression, reflecting local microtopographic evolution. Based on sedimentary facies and dating results, no transgressive sediments were observed during marine isotope stage (MIS) 3, and T2 (Xianxian transgression) in the southern coastal Bohai Sea only occurred in MIS 5e. This sedimentary sequence pattern is consistent with global sea-level changes.