晚更新世早期共和盆地湖相沉积常量元素地化学特征及环境演变  

Geochemical characteristics of major element oxides and environmental evolution inferred from lacustrine sediments in Gonghe Basin,China during the early Late Pleistocene

作　　者：胡梦珺[1] 郑登友 吉天琪 庄静 孙文丽 Hu Mengjun;Zheng Dengyou;Ji Tianqi;Zhuang Jing;Sun Wenli(College of Geography and Environment Sciences,Northwest Normal University,Lanzhou 730070,China)

机构地区：[1]西北师范大学地理与环境科学学院,甘肃兰州730070

出　　处：《中国沙漠》2022年第1期147-157,共11页Journal of Desert Research

基　　金：国家自然科学基金项目(41171018,41161036)。

摘　　要：对共和盆地过马营沙沟湖相沉积剖面常量元素氧化物及比值特征进行分析,结合光释光测年,探讨了共和盆地晚更新世早期的环境演变。结果表明:(1)SiO2和Na/K自剖面底部向上大致呈现出一谷两峰的变化特征,整体波动增大,高值均出现在细砂层,指示冷干气候;低值出现在粉砂层,指示温湿气候;(2)CaO、MgO与CIA值自剖面底部向上大致呈现出一峰两谷的变化特征,整体呈现波动减小的态势,高值均出现在粉砂层,指示湿润气候;低值出现在细砂层,指示冷干气候;(3)共和盆地气候在90—70 ka存在3次明显的冷干-温湿波动,可分为MIS 5b(91.5—89.4 ka)气候由温润向凉干方向发展的共和古湖低水位期、MIS 5a(89.4—80.1 ka)气候温湿的湖泊高水位期和MIS 4(80.1—70.1 ka)气候冷干的湖泊萎缩期。By analyzing the characteristics of major element oxides and their ratios in the sediment of the Shagou section in the Gonghe Basin,combined with the photoluminescence dating,we studied the environmental evolution of the early Late Pleistocene in Gonghe Basin. The results show that:(1)From the bottom to the top of the section,the SiO2 content and Na/K ratio generally show the characteristic of "one valley and two peaks",with an overall increasing trend. The high values all appear in the fine sand layer,indicating a cold and dry climate. The low values appear in the silt layer,indicating a warm and humid climate.(2)From the bottom to the top of the section,the CaO,MgO contents,and CIA ratio generally show a change characteristic of "one peak and two valleys",with an overall decreasing trend. The high values all appear in the silt layer,indicating a warm and humid climate. The low values appear in the fine sand layer,indicating a cold and dry climate.(3)The climate of the Gonghe Basin has three obvious cool/dry-warm/humid fluctuations between 90-70 ka. Those fluctuations are divided into three stages. MIS 5 b(91.5-89.4 ka)stage is the low water level period of the ancient Gonghe Lake that the climate develops from warm to cool-dry;MIS 5 a(89.4-80.1 ka)stage is the high water level period of lakes with warm and humid climate;and MIS 4(80.1-70.1 ka)stage is the shrinking period of lakes with cold and dry lakes.

关 键 词：共和盆地 常量元素氧化物 水成沉积 环境演变 

分 类 号：P595[天文地球—地球化学]