Characteristics and Paleoclimatic Significance of Magnetic Susceptibility and Stable Organic Carbon Isotopes from a Bore in Zhoulao Town, Jianghan Plain

Jianghan plain lies in Chinaese east-west and south-north natural transition area. The study of climate change in this area from 30 ka plays an important part in understanding global paleoclimatic events and has been given increasing attention. In this paper, based on ¹⁴C dating, an analysis is made of magnetic susceptibility and stable organic carbon isotopes from the bored core in Zhoulao town, Jianghan plain. The results indicate that (1) magnetic susceptibility and stable organic carbon isotopes in this area have good coherence and relativity in the patterns of their evolution. Their relation to paleoclimate is that the higher values of magnetic susceptibility and the stable organic carbon isotope correspond to a colder and drier environment, while the lower values correspond to a warmer, wet environment. (2) According to the pattern of change of magnetic susceptibility and stable organic carbon isotopes, the sequence of climate change from 30 kaB.P. can be divided into 3 main stages: the age of the first stage varies from 30 000-14 100 aB.P., and the average value of magnetic susceptibility and δ¹³C is 655.69 ×10^-6SI and -23.15×10^-3 respectively, with a relatively high vibration curve, which is the highest of the three stages; the age of the second stage is from 14 100-3 540 aB.P., and the magnetic susceptibility and δ¹³C have a low vibration curve with average values of 369.38 ×10^-6SI and -27.29×10^-3; the age of the third stage is between (3 540-) 650 aB.P. and the average value of magnetic susceptibility is 311.0 ×10^-6SI, the lowest of the three stages, and that of δ¹³C is -24.49×10^-3, also with a high vibration curve. Each stage can be further subdivided into several climatic events. (3) The sudden change of magnetic susceptibility and organic carbon isotopes may indicate a sudden temperature change.