OSL chronology of the Huksan Mud Belt, south-eastern Yellow Sea, and its paleoenvironmental implications

Abstract

The Huksan Mud Belt (HMB) is located in the south-eastern Yellow Sea. The radiocarbon (14C) and optically stimulated luminescence (OSL) age datings of the pre-Holocene HMB sediments were compared precisely. OSL dates for the uppermost HMB sediments showed the recent and short-term chronological development of the HMB. OSL and 14C ages of the Holocene sediment (HMB cores 101–103) were relatively consistent. By contrast, the OSL ages of the pre-Holocene sediment unit were considerably older than the 14C ages (by approximately 30%), where the OSL ages corresponded broadly to marine isotope stages (MIS) 5 and 4 (from about 125 ka to > 50 ka). An overall comparison of 14C and OSL dates suggests that the age of the Holocene mud unit is well constrained by 14C dating. However, 14C ages older than 40 ka may be unreliable. The surficial sedimentation rate and depositional ages for a 6.5-m-thick sequence of the uppermost unit (12HMB cores) were determined. Twenty OSL samples gave an age of approximately 8.5 ka. Most of the OSL ages for each site were in stratigraphic order. The surficial sediment ages for the 12 HMB cores were 2.6 ka for P-08, 7.7 ka for P-10, 7.3 ka for P-11, and 0.05 ka for P-14. The approximate surficial sediment ages of the uppermost unit of the HMB-101, -102, and −103 cores were 6.7 ka, 6.8 ka, and 1.1 ka, respectively. The spatiotemporal differences in deposition and erosion of the HMB Holocene muds, supposedly driven by changes in large, strong tidal forces and marine water depth, and an increase in ocean current velocity, could account for the various surficial deposition ages in the area.