六盘山群火石寨剖面沉积物色度纪录的128.10～115.30 Ma气候变化  

Climate changes during 128.10～115.30 Ma recorded by colors of sediments in the Liupanshan basin along Huoshizhai section

作　　者：孔立[1] 戴霜[1] 刘学[1] 朱强[2] 赵杰[1] 张明震[1] 黄永波[1] 刘俊伟[1] 

机构地区：[1]兰州大学西部环境教育部重点实验室,兰州730000 [2]中国科学院寒区旱区环境与工程研究所,兰州730000

出　　处：《兰州大学学报（自然科学版）》2010年第5期44-49,55,共7页Journal of Lanzhou University(Natural Sciences)

基　　金：国家自然科学基金项目(40972025;40721061;40571017);教育部新世纪人才计划项目(NCET-07);国家重点基础研究发展计划(973计划)项目(2005CB422001);高等学校学科创新引智计划项目(B06026)

摘　　要：通过对六盘山盆地火石寨剖面沉积物连续采样和色度测量,结合地层沉积及磁性地层年龄,获得128.10～115.30 Ma色度变化序列.发现在地表冲积扇—辫状河沉积环境亮度值低并呈升高趋势、红度黄度值高且逐渐降低,在滨浅湖环境色度值趋势性不明显,波动幅度不大;亮度值与岩石胶结物有关,而红度值与赤铁矿质量分数有关.综合沉积环境、岩石及色度值变化分析表明:六盘山地区128.10～115.30 Ma气候变化分为128.10～125.00 Ma相对湿热阶段和125.00～115.30 Ma相对温湿阶段,基本与全球海平面温度变化趋势一致.气候转型以沉积相变化和色度值的渐变为特征,转型时间比全球海平面温度在123.30 Ma由高到低转变提前约1.70 Ma,说明陆地系统比海洋系统对全球变化的响应更敏感.High-resolution sampling and color measurement of the sediments along the Huoshizhai section （northern of the Liupanshan basin） were carried out and the successive color variations during 128.10-115.30 Ma were obtained. The brightness value was low and gradually increased, and the value of redness and yellowness was high and gradually decreased in the alluvial and braided river depositional environment. The variations of the color value were not significant in the shore and shallow lake environment. The variations in brightness value were related to rock cement and the redness to hematite content in the sediments. Analysis of the color variations, together with the depositional environment and lithology, shows that the climate changes in Liupanshan basin during 128.10-125.00 Ma could be divided into relatively wet-hot stage during 125.00-115.30 Ma and relatively wet-warm stage during 128.10-115.30 Ma, which were approximately consistent with the trend of global sea-surface temperature. Climate transition was characterized by changes in sedimentary facies and the gradual change of color values, whose occurring time was about 1.70 Ma prior to the transition of the global sea-surface temperature at 123.30 Ma, thus indicating that the land systems were more sensitive to global changes than the marine systems.

关 键 词：色度 气候变化 早白垩世 六盘山群 

分 类 号：P532[天文地球—古生物学与地层学]