青土湖沉积物粒度特征及其古环境意义  

GRAIN-SIZE CHARACTERISTICS OF QINGTU LAKE SEDIMENTS AND ITS PALEAOENVIRONMENT EXPLAINATION

作　　者：赵强[1] 王乃昂[1] 程弘毅[1] 谌永生[1] 郭剑英[1] 

机构地区：[1]兰州大学资源环境学院地理系,甘肃730000

出　　处：《干旱区地理》2003年第1期1-5,共5页Arid Land Geography

基　　金：国家自然科学基金重点项目 (批准号 :497310 10 );国家自然科学基金项目 (批准号 :40 0 710 31)资助

摘　　要：青土湖沉积物的粒度特征反映了青土湖降水、水动力搬运强度以及湖面水位高低的变化。利用石羊河古终端湖泊青土湖剖面沉积物的粒度资料 ,分析了粒度组成、粒度参数等粒度特征 ,并探讨了古终端湖泊的沉积环境。结果表明青土湖从 110 0 0aBP年以来大致经历了 4次极端干旱时期和 4次温暖时期。通过对青土湖沉积物粒度频率曲线的分析 ,讨论了湖泊的几种可能沉积作用 ,区分出了湖相沉积、风成沉积浅湖相沉积以及水流和风力作用混合沉积 ,从而揭示了沉积时的古环境特征。青土湖全新世以来的环境演变 ,具有连续和沉积速率大的特点 ,不仅可以作为古环境与古气候变化的自然记录 ,而且为研究本区土地退化、荒漠化等问题提供了自然背景。The enclosed Qingtu Lake lies in the environment-sensitive zone in Minqin County of Gansu Province, China,and the grainsize characteristics of its sediments indicate the variations of precipitation,hydrodynamics and the lake level changes.The grain size characteristics of Qingtu Lake sediment,part of palaeoterminal lake of Shiyang River,are analyzed in this paper,including grain size distribution,grain size parameters. Based on the analysis of the characteristics of the grain-size frequency curves of the lake sediments,some possible major depositions like fluvial deposition, wind deposition, low-lake deposition and lake deposition are discussed. The results indicate the palaoterminal lake of Shiyang River had erperienced four warm period and four dry period since 11 000a BP. In brief,the evolution of lakes in Eastern Hexi Corridor is characterized by sedimentary continuity and faster sedimentary rate,which not only can indicate the paleoenvironmental and climate change in Holocence,but also provide natural background of the soil regeneration and desertification.

关 键 词：沉积物 粒度特征 古环境 青土湖 古气候 全新世 沉积速率 

分 类 号：P531[天文地球—古生物学与地层学]