摘要
江汉平原地处我国东西、南北自然环境的过渡地带 ,该地带距今 30ka(大约相当于MIS3阶段 )以来的气候变化是研究过去全球气候变化的重要时段之一 ,已越来越引起人们的关注 .在精确测年的基础上 ,对采自江汉平原湖区周老镇钻孔(ZL0 1 )沉积物柱样的磁化率和有机碳稳定同位素进行了处理和分析 ,其结果表明 :( 1 )该区磁化率和有机碳稳定同位素值的变化特点具有较好的一致性和可对比性 ,它们与古气候的关系为 :磁化率的高值、有机碳稳定同位素的偏正值与偏冷、偏干的气候环境相对应 ;反之与偏温暖湿润的气候环境相对应 .( 2 )根据磁化率和有机碳稳定同位素值的变化特点将本区30kaB .P .以来的古气候分为 3个大的气候演化阶段 ,在每一个大的气候演化阶段中又可分为若干次小的气候演变阶段 .这 3个大的气候演化阶段分别为阶段Ⅰ :其年龄约为 30 0 0 0～ 1 4 1 0 0aB .P .,磁化率和δ1 3 C的平均值分别为 6 5 5 .6 9× 1 0 -6SI和 - 2 3.1 5× 1 0 -3 ,均为本区最高值并且曲线波动较大 ;阶段Ⅱ :相应时段为 1 4 1 0 0～ 35 4 0aB .P .,磁化率平均值为较低值 36 9.38× 1 0 -6SI和δ1 3 C为偏负值 ( - 2 7.2 9× 1 0 -3 ) ,相对较稳定 ;阶段Ⅲ :年代相当于 35 4 0～ 6 5 0aB .P .,平均磁化率为本区最低值 31 1 .
Jianghan plain lies in Chinese 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 30000-14100 aB.P., and the average value of magnetic susceptibility and δ13C is 655.69 × 10-6 SI 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 14100-3540 aB.P., and the magnetic susceptibility and δ13C have a low vibration curve with average values of 369.38 × 10-6 SI and -27.29 × 10-3; the age of the third stage is between 3540-650 aB.P. and the average value of magnetic susceptibility is 311.0 × 10-6 SI, 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.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2005年第1期114-120,共7页
Earth Science-Journal of China University of Geosciences
基金
国家重点基础研究"973"项目 (Nos.2 0 0 1CCB0 0 1 0 0
2 0 0 4CB72 0 2 0 4)
国家自然科学基金项目 (Nos.40 472 1 5 1
40 372 0 79
90 41 1 0 0 5 )
