古尔班通古特沙漠南缘沉积记录的沙漠-绿洲演化特征  

Sedimentary Records of the Southern Margin of the Gurbantunggut Desert Desert-Oasis Evolution Characteristics

作　　者：陶通炼 谭典佳 李志忠[1,2,3] 靳建辉[1,2] 马运强 邹晓君 TAO Tonglian;TAN Dianjia;LI Zhizhong;JIN Jianhui;MA Yunqiang;ZOU Xiaojun(School of Geographical Sciences&School of Carbon Neutrality Future Technology,Fujian Normal University,Fuzhou 350117,China;Subtropical Fujian Provincial Key Laboratory of Resources and Environment,Fujian Normal University,Fuzhou 350117,China;Institute of Geography,Fujian Normal University,Fuzhou 350117,China)

机构地区：[1]福建师范大学地理科学学院、碳中和未来技术学院,福州350117 [2]福建师范大学福建省亚热带资源与环境重点实验室,福州350117 [3]福建师范大学地理研究所,福州350117

出　　处：《亚热带资源与环境学报》2024年第3期197-206,共10页Journal of Subtropical Resources and Environment

基　　金：国家自然科学基金项目(42071011)。

摘　　要：干旱区沙漠和绿洲是在一定条件下可以互相转化的共生景观,阐明两者转化机制对于理解干旱区现代地表过程和生态环境演变趋势具有重要意义。在古尔班通古特沙漠南缘采集地表不同类型沉积物样品,通过实验分析获取了表征现代沙漠和绿洲沉积特征的粒度端元组分、MgO/SiO_(2)比值、绿洲指数[(Mn+Cu+Zn)/SiO_(2)]和淋溶系数[SiO_(2)/(MgO+CaO+K_(2)O+Na_(2)O)]等指标参数,并检验了这些指标在提取地层记录的沙漠化和绿洲化信息方面的可靠性。结果表明:(1)现代绿洲沉积细组分端元(EM1)含量较高,且MgO/SiO_(2)比值和绿洲指数也较大,但淋溶系数较小,而沙漠沉积粗组分端元(EM3)含量较高、淋溶系数较大,但MgO/SiO_(2)比值和绿洲指数较小。(2)地层剖面中厚层或多层叠加的黏土-粉沙沉积粒度端元组分、绿洲指数和淋溶系数等指标与现代绿洲沉积相似,而厚层或多层叠加的极细沙、细沙沉积各指标与现代沙漠沉积相似。(3)在OSL年代标尺基础上,综合运用以上代用指标提取地层记录的沉积环境演变信息,并对比毗邻区域代表性地质记录分析显示,在11.1×10^(3)~10.2×10^(3) a、6.0×10^(3)~3.8×10^(3) a、约2.8×10^(3) a的多层细沙和极细沙层反映气候干旱、风沙活动较强,沙漠波动扩展;而10.2×10^(3)~6.0×10^(3) a发育的多层黏土-粉沙层反映气候相对湿润、河流作用活跃、绿洲广泛发展,沙漠大幅度收缩;约3.8×10^(3) a以来,在趋向现代景观格局的过程中,沙漠与绿洲范围此消彼长、多次转换。Deserts and oases in arid regions are symbiotic landscapes that can be transformed into each other under certain conditions.Clarifying the transformation mechanism of deserts and oases is of great significance for understanding the modern surface processes and ecological environment evolution trends in arid region.Different types of surface sediment samples were collected in the southern margin of the Gurbantunggut Desert.Geochemical parameters such as grain-size end-member composition,MgO/SiO_(2) ratio,oasis index[(Mn+Cu+Zn)/SiO_(2)]and eluvial coefficient[SiO_(2)/(MgO+CaO+K 2O+Na 2O)]were obtained to characterize the sedimentary characteristics of modern deserts and oases.The reliability of these indicators in extracting the information of desertification and oasisization from stratigraphic records is also examined.The results show that,(1)the oasis sediments are characterized by high contents of fine-grained particle(EM1),oasis index,and MgO/SiO_(2),and low values of the eluvial coefficient.By contrast,the desert sediments are characterized by high values of coarse-grained particle(EM3),low oasis index and MgO/SiO_(2),and an increased eluvial coefficient.(2)The grain size end-member composition,oasis coefficient and leaching coefficient of thick or multi-layer superimposed clay-silt deposits in the stratigraphic section are similar to modern oasis deposits,while the indexes of thick or multi-layer superimposed very fine sand and fine sand deposits are similar to modern desert deposits.(3)Based on the OSL chronology scale,the above proxy indicators are used to extract the sedimentary environment evolution information recorded by the strata,and compared with the representative geological records of the adjacent area.The analysis shows that the multi-layer fine sand and very fine sand layers of 11.1×10^(3)~10.2×10^(3) a,6.0×10^(3)~3.8×10^(3) a,and about 2.8×10^(3) a reflect the arid climate,strong wind and sand activities,and the expansion of desert fluctuations;the multi-layer clay-silt layer developed in 1

关 键 词：古尔班通古特沙漠 粒度端元组分 特征元素比值 沙漠化和绿洲化 全新世 

分 类 号：K903[历史地理—人文地理学]