摘要
以青藏高原东北部泽库剖面(ZK)风成沉积物为研究对象,利用CM-5分光测色计测定了169个样品的色度参数红度(a^(*))、黄度(b^(*))、亮度(L^(*))并计算饱和度(C^(*))和色调角(h^(*)),在分析风成沉积物各色度参数变化特征的基础上,辅以磁化率、粒度敏感指数(SC/D)、Si O_(2)及Fe_(2)O_(3)含量等指标对青藏高原东北部9.4 ka以来的环境演变进行探讨。研究结果表明:(1)色度参数a^(*)、L^(*)自剖面底部向上呈先增大后减小的变化特征,h^(*)则自下而上先减小后增大。(2)色度参数可作为青藏高原东北部重建古气候的有效代用指标,a^(*)和L^(*)高值指示温湿环境,h^(*)高值指示冷干环境;各色度参数指示环境的敏感性有差异,但均对气候突变反应较为灵敏,可用于判断气候突变的典型冷暖事件。(3)9.4 ka以来青藏高原东北部的环境整体呈现为由温湿向冷干发展的态势,可分为两大阶段。9480~4290 a BP的温湿期,气候整体呈现向温湿方向发展的趋势,表现为较温湿→温湿→较温湿的波动;4290 a BP至今的冷干期,气候整体不断向冷干方向发展,表现为温干→温润→凉润→冷干的变化。
Eolian sediments from the Zeku profile(ZK)of the northeastern Tibetan Plateau as the object of the study.The chromaticity parameters a^(*),b^(*),L^(*)and the calculation of C^(*)and h^(*)of 169 samples were meas-ured by CM-5 spectrophotometer,and the environmental evolution of the northeastern Tibetan Plateau since 9.4 ka was discussed based on the analysis of the variation characteristics of each chromaticity parameter of wind-formed sediments,supplemented with the indexes of magnetization rate,SC/D,SiO_(2)and Fe_(2)O_(3).The results shows that:(1)From the bottom to the top of the profile,the chromaticity parameters a^(*)and L^(*)are character-ized by increasing first and then decreasing.(2)Chromaticity parameters can be used as effective proxies for reconstruction the paleoclimate on the northeastern Tibetan Plateau.The high values of a^(*)and L^(*)indicate the warm-wet environment,and the high values of h^(*)indicate the cold-dry environment.Chromaticity parameters indicate different environmental sensitivities,but they are sensitive to climate abrupt change,which can be used to judge the typical cold and warm events of climate abrupt change.(3)The environment in the northeastern Tibetan Plateau since 9.4 ka has shown a development situation from warm-wet to cold-dry,which can be divid-ed into two major stages.During 9,480-4,290 a BP,the climate was temperatureandhumidity,showing fluctu-ations of warmer and wetter→warmer and wetter→warmer and wetter.After 4,290 a BP,the climate wascold and dry,the climate as a whole is cold and dry,showing a change of warm and dry→warm→cool→cold and dry.
作者
胡梦珺
吉天琪
郑登友
庄静
孙文丽
许澳康
HU Mengjun;JI Tianqi;ZHENG Dengyou;ZHUANG Jing;SUN Wenli;XU Aokang(College of Geography and Environmental Science,Northwest Normal University,Lanzhou,Gansu 730070,China)
出处
《现代地质》
CAS
CSCD
北大核心
2022年第2期439-448,461,共11页
Geoscience
基金
国家自然科学基金项目(41171018,41161036)。
关键词
色度参数
环境演变
青藏高原东北部
chromatic parameter
environmental evolution
northeastern Tibetan Plateau
