Benthic foraminifer record of environmental changes in the Yellow Sea (Hwanghae) during the last 15,000 years

Abstract

Latest Quaternary benthic foraminifer census counts in four cores from the Yellow Sea (Hwanghae) were analyzed to decipher paleoenvironmental changes in this area since the Last Glacial Maximum. Principal component analyses of samples from two cores in the central Yellow Sea indicate that the faunal variation in these cores reflects a sequence of distinct assemblages divided by sharp boundaries. The shifts between individual biofacies correspond to changes in geochemical and lithological composition of the sediments, and stable-isotope ratios of foraminiferal shells, and most can be correlated between cores. The major faunal transition, at a clear increase in bottom-water salinity, occurred between 8.47 and 6.63 ka, and may indicate the establishment of modern-type circulation in the Yellow Sea. The inferred threshold size of the Yellow Sea Basin for the establishment of such circulation seems to be rather close to its present-day extent. Faunal shifts at 10.6 and 4.67 ka probably reflect changes in the intensity of river runoff, associated sediment and organic carbon delivery, and bottom-water oxygenation. Changes in benthic foraminifer faunas between 12.9 and 11.75 ka may signal the Younger Dryas climatic oscillation in the Yellow Sea. The Lateglacial marine transgression reached the central part of the Yellow Sea around 15.09 ka. Possibly, an uplift of the central and eastern Yellow Sea area during the late Holocene can explain the discrepancy between the timing of the transgression in the Yellow Sea and the global sea-level curve.