藏北库木库里盆地KM剖面晚更新世沉积物粒度特征及其环境意义  

Grain-size characteristics and environmental significance of late Pleistocene sediments at KM section in Kumukuli Basin,northern Tibetan Plateau

作　　者：吴晓英[1] 张倩雯[2] 张志高[3] 滕晓华[4] 苗运法[5] 卓世新 严永耀 

机构地区：[1]兰州资源环境职业技术学院,兰州730021 [2]武汉大学资源与环境科学学院,武汉430079 [3]安阳师范学院资源环境与旅游学院,河南安阳455002 [4]兰州大学西部环境教育部重点实验室,兰州730000 [5]中国科学院寒区旱区环境与工程研究所沙漠与沙漠化重点实验室,兰州730000 [6]中国气象哈密地区气象局,新疆哈密839001

出　　处：《兰州大学学报（自然科学版）》2015年第4期478-487,495,共11页Journal of Lanzhou University(Natural Sciences)

基　　金：国家自然科学基金项目(41172153);中国科学院盐湖资源与化学重点实验室开放基金项目(KLSLRC-KF-13-DX-1)

摘　　要：对青藏高原东北缘库木库里盆地阿牙克库木湖南缘的KM剖面沉积物进行了粒度分析,剖面粒度组成主要以细粉砂和砂粒占优势,质量分数分别为39.2%、26.9%.剖面粒度整体分选较差,频率分布曲线呈现多峰分布的特征,偏度从极负偏到正偏、峰态从窄到宽,反映了多种搬运方式存在;各粒度组分的分析结果表明研究区气候演化可以划分为5个阶段:1)22.0～21.0 ka BP气候冷干,湖泊水位低,西风较强,沙尘暴频繁;2)21.0～16.0 ka BP气候较前一阶段湿润,湖泊水位升高,西风减弱,沙尘暴减少;3)16.0～10.5 ka BP气候冷干、不稳定,波动幅度大,风力作用强,湖泊水位浅,沙尘暴增多;4)10.5～3.5 ka BP气候最为暖湿,西风减弱,湖水水位上升,湖泊水位达到剖面最高;5)3.5～2.0 ka BP湖泊水位降低,风力作用较强,气候变得干冷.末次盛冰期以来,受控于北大西洋气候的西风起主导作用,研究区气候随着西风的增强而变得冷干,湖泊水位降低,沙尘暴较为频繁,直至全新世受控于北纬65?太阳辐射强度的季风占主导作用,气候最为暖湿,沙尘暴较少,晚全新世以来随着太阳辐射的减弱,季风减弱,气候再次朝着冷干方向发展.Grain-size analyses of the sediments of KM section in southern Ayakekumu lake, northeastern Tibetan Plateau, indicated that sediments of KM section is mainly composed of fine silty sand and sand components, their contents being 39.2% and 26.9% respectively. The sorting is poor, the frequency distribution curves mainly contain several peaks, the skewness is from negative to positive, and kurtosis from narrow to wide, indicating a variety of transportation patterns. Based on the analysis of the grain-size distribution, this paper reconstructed the sedimentary paleo-environment of the study area as five sections： 1） 22.0~21.0 kaBP： the grain-size distribution reflects a cold and dry climate when the lake level was low and westerlies were strong with frequent dust storms; 2） 21.0~16.0 kaBP： the climate was humid, instable and compared with the previous stage, the lake level rose, the westerlies weakened and sand storms decreased; 3） 16.0~10.5 kaBP： the climate became cold and dry, the lake level was shallow, wind was strong and dust storms increased, but being instable and kurtosis; 4） 10.5~3.5 kaBP： the climate was humid, the westerlies weakened and the lake level reached the highest; 5） 3.5~2.0 kaBP： the lake level was reduced, the wind was strong, and the climate became dry and cold. Since the last glacial maximum, the westlies, controlled by the North Atlantic climate, had played a leading role, the clinmte became dry and cold with the enhancement of westerly, the lake level was reduced and dust storms increased. Until the Holocene, the monsoon, controlled by the intensity of solar radiation in the northern hemisphere＇s 65~ latitudes, had dominated the region, when the climate became humid and dust storms decreased. During the late Holocene, the climate became dry and cold with weakened monsoon and solar radiation.

关 键 词：晚更新世 粒度 湖泊沉积物 库木库里盆地 

分 类 号：P512[天文地球—地质学]