青海湖东岸沙地风成沉积物粒度敏感组分及其古气候意义  

Extraction of Grain-size Components with Environmentally Sensitivity of Aeolian Sediments in Eastern Shore of Qinghai Lake and Their Palaeoclimatic Implications

作　　者：李腾飞[1] 李金凤[1] 鲁瑞洁[1] 刘小槺 陈璐[1] 

机构地区：[1]北京师范大学地表过程与资源生态国家重点实验室/防沙治沙教育部工程研究中心/地理科学学部,北京100875

出　　处：《中国沙漠》2017年第5期878-884,共7页Journal of Desert Research

基　　金：国家自然科学基金项目(41571184;41171159);国家重点基础研究发展计划项目(2013CB956001)

摘　　要：粒级-标准偏差的计算可用来提取沉积序列的粒度敏感组分。采用线性粒级和对数粒级两种粒度划分方法 ,对青海湖东岸沙地多个风成砂-古土壤沉积剖面进行了系统分析。结果表明:粒级划分对于敏感组分提取结果具有一定的影响,对数粒级提取的粗粒敏感组分比细粒组分具有更大标准偏差,而线性粒级的提取结果则显示细粒组分对于环境变化更为敏感;两种方法提取的细粒敏感组分差异较大,而较粗组分和粗粒组分较为一致。在运用粒级-标准偏差法提取环境敏感粒度指标时,两种划分方法都能有效地提取粗粒敏感组分,而在提取细粒敏感组分方面线性粒级较对数粒级划分法能取得更好的效果。采用线性粒级-标准偏差法提取了青海湖东岸沙地风成沉积物粒度敏感组分,发现黏粒组分(0~4μm)可以作为夏季风强度变化的替代性指标,中细砂组分(144~321μm)可以指示风沙活动的强弱,极细砂组分(60~126μm)可能受局部地形的影响较大,其古气候意义有待进一步查明。Graded-standard deviation can be used to extract the sensitive grain-size component in sedimentary sequences.In this paper,multiple aeolian sand/paleosol sedimentary sections in eastern Qinghai Lake were analyzed by this method.The results showed that division had an influence on sensitive components extraction result.The coarse sensitive components had larger standard deviation value than fine-grained components extracted by the logarithmic graded-standard deviation,while using linear graded-standard deviation,the extracted fine grained components were more sensitive to environmental changes;Fine grain sensitive component extracted by two methods had a great difference,and coarse grain were relatively consistent,suggesting that graded.When using graded standard deviation method to extract environmental sensitive components,both methods could extract coarse sensitive components effectively,meanwhile linear graded-standard deviation could obtain better effect in extracting fine grained sensitive components.With the method of linear graded-standard deviation,we found that the clay fraction（0-4μm）can be used as a proxy of summer monsoon,while medium and fine sand fraction（144-321μm）should be used for indicating the strength of aeolian activity,and very fine sand component（60-126μm）may be influenced by local terrain,its paleoclimatic significance remains to be further identified.

关 键 词：青海湖 粒度 古气候 风沙活动 

分 类 号：P931.3[天文地球—自然地理学]