Records of Organic Carbon Isotopic Composition and Its Paleoenvironmental Implications in Shengshan Island Loess Deposition in the East China Sea during the Last Glacial Period

Organic carbon isotopic composition (δ¹³C_org) in loess deposits is an important indicator of terrestrial paleovegetation, and it has been widely used for paleoenvironmental reconstruction in aeolian sediments around the world. However, little research has been done on the variation and paleoenvironmental implication of δ¹³C_org from loess deposits on Shengshan Island, East China Sea, during the last glacial period (LG). In this research, we present optically stimulated luminescence (OSL) ages, total organic carbon (TOC) data and δ¹³C_org records of the loess section at Chenqianshan (CQS) on Shengshan Island. Additionally, to study the effectiveness of δ¹³C_org in documenting paleoenvironmental changes, magnetic susceptibilities and diffuse reflectance spectra were surveyed. TOC concentration for the CQS loess section ranged from 0.11% to 0.47%, and the δ¹³C_org composition of the CQS loess section varied between −20.80‰ and −24.56‰ during the LG. The average value of C₄ abundance was 21.31%. TOC, δ¹³C_org, χ_fd, and Hm/(Hm + Gt) curves for the CQS loess section showed similar patterns. The results of our study indicated that the vegetation of the CQS loess deposit was mainly C₃/C₄ mixed vegetation, and C₃ vegetation was the most important vegetation. The comparison between the δ¹³C_org curve for the CQS section and other existing δ¹³C_org records of the loess sections from central and northern China showed similar trends and their vegetation succession exhibited synchronous change during the LG. Based on a comparison of the δ¹³C_org record, C₄ abundance and χ_fd of the CQS section and other global geological records, it was concluded that the mutual effects of precipitation and temperature caused the change of paleovegetation in loess deposits on islands in the East China Sea during the LG.