Evolution of the Yellow Sea Warm Current and the Yellow Sea Cold Water Mass since the Middle Pleistocene

Abstract

The Yellow Sea Warm Current (YSWC) and the Yellow Sea Cold Water Mass (YSCWM) are the most significant hydrological characteristics of the Yellow Sea as they strongly influence the matter transportation, sedimentation, and the benthic and pelagic environments of the region. Previous studies focused mostly on formation and evolution of the YSWC and the YSCWM on shorter time scales (e.g., since the Holocene) and studies on longer time scales are rather sparse. This study conducted a high-resolution magnetostratigraphic investigation on core DLC70-3 (with a water depth of 71.2m) in the northern part of the south Yellow Sea. Results show that the Brunhes/Matuyama polarity reversal boundary is located at a depth of 59.08m. Constrained by both magnetostratigraphy and 14C dating, three sedimentation episodes revealed by the benthic foraminifera content correspond to high sea level periods of marine isotope stage (MIS) 5–MIS9, MIS11–MIS17, and MIS19–MIS21, respectively. Cold-water benthic foraminifera species, total organic carbon, total sulfur, molybdenum element, and long-chain unsaturated alkenones index of the studied sediments show that both the YSWC and the YSCWM have evolved since the middle Pleistocene mainly due to combined effects of fluctuations of sea level and local tectonic subsidence. More specifically, both the YSWC and the YSCWM were intensified during high sea level periods of MIS5e–MIS9, MIS19 and MIS21. In addition, occurrence of the YSWC and the YSCWM are not always coeval as in the MIS5a–5d period, which is characterized by relatively stronger YSCWM but absence of the YSWC. These studies significantly improve our understanding of the evolution mechanism of both the YSWC and the YSCWM in this region.