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引用本文:丁宗艳,张家武,杨盼盼,周姗,张玉枝.柴达木盆地托素湖不同位置岩芯沉积物指标对比及其环境意义.湖泊科学,2020,32(1):259-270. DOI:10.18307/2020.0124
DING Zongyan,ZHANG Jiawu,YANG Panpan,ZHOU Shan,ZHANG Yuzhi.Comparison of sediment proxies of cores and their environmental significance at different locations of Lake Toson in Qaidam Basin. J. Lake Sci.2020,32(1):259-270. DOI:10.18307/2020.0124
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柴达木盆地托素湖不同位置岩芯沉积物指标对比及其环境意义
丁宗艳, 张家武, 杨盼盼, 周姗, 张玉枝
兰州大学资源环境学院, 西部环境教育部重点实验室, 兰州 730000
摘要:
湖泊不同位置岩芯沉积物相同代用指标的变化是否一致对于重建可靠的区域气候变化历史至关重要.目前多数研究仅利用深水区单一的沉积岩芯来反演区域的气候环境变化,对于不同位置岩芯重建结果的异同尚缺乏研究.本文选择托素湖不同位置、不同水深的4根短钻岩芯沉积物,在放射性核素(210Pb和137Cs)定年的基础上,对比分析各岩芯沉积物粒度、碳酸盐含量等代用指标的变化情况.结果显示,湖泊内相近的沉积岩芯沉积物粒度变化相似,但相距较远的岩芯之间粒度变化差异较大;浅水区的沉积物粒度(粒径或组分含量)在短时间尺度上变化很大,而深水区的沉积环境比较稳定,在百年尺度上的变化不明显;有机质与碳酸盐含量总体变化趋势一致且有较好的相关性,表明碳酸盐可能受到湖泊生产力的影响.碳酸盐含量、碳酸盐氧同位素(δ18O)和TL06孔孢粉的A/C比值变化基本一致,反映的有效湿度变化与同期气象记录的相对湿度一致,但与降水量和蒸发量的变化不一致.因此,托素湖粒度指标仅指示不同位置钻孔沉积环境状况,与气候变化的关系并不明显,用碳酸盐及其同位素等地球化学指标恢复区域气候变化历史更可靠.
关键词:  平均粒径  碳酸盐含量  有机质  代用指标  托素湖  柴达木盆地
DOI:10.18307/2020.0124
分类号:
基金项目:国家自然科学基金项目(41771212)和兰州大学中央高校基本科研业务费专项(lzujbky-2017-it81)联合资助.
Comparison of sediment proxies of cores and their environmental significance at different locations of Lake Toson in Qaidam Basin
DING Zongyan, ZHANG Jiawu, YANG Panpan, ZHOU Shan, ZHANG Yuzhi
Key Laboratory of Western China's Environmental Systems, Ministry of Education, College of Earth Environmental Sciences, Lanzhou University, Lanzhou 730000, P. R. China
Abstract:
The consistency of proxies at different locations in a lake is of great importance to the reliability of regional climate reconstruction. At present, a single core in the central/deep lake was usually used to reconstruct the regional climate and environment change without verification. Here we compare the same proxy among the different core sediments from different locations of Lake Toson (37°04'-37°13'N, 96°50'-97°03'E, 2808 m a.s.l), which is located in Delingha, NE Tibetan Plateau. Core TSL15S1, TSL15S3, TSL15S7 and TSLG17 were recovered at the water depth of 1, 16.5, 16.5 and 25 m in Lake Toson, respectively. Based on the dating of 210Pb and 137Cs analyses, the changes of grain size, carbonate content and other proxies were compared and analyzed. The results show that the mean grain size is consistent at similar locations, while the grain size are quite different at distant locations within the lake. The grain size of sediments in the shallow water vary greatly in a short time scale, while the sedimentary environment in deep water is relatively stable, and the change is not obvious in the centurial. The variations of organic matter and carbonate content are consistent with each other, which indicates that carbonate may be affected by lake productivity. The organic matter content can reflect the size of lake productivity. The variations of carbonate content are consistent with the carbonate oxygen isotope in TSLC and the pollen A/C ratio of TL06, which was regarded as the substitute index of regional effective humidity. Therefore, the grain size in Lake Toson is reflecting the local sedimentary environment, and its relationship with the regional climate is not clear. Geochemical indexes are more reliable and are recommended for environment reconstructions in a well-mixed lake.
Key words:  Average particle size  carbonate content  organic matter  environmental proxies  Lake Toson  Qaidam Basin
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