长江三角洲风尘黄土与大气粉尘物源识别对比研究

Loess in East China is an important component of Chinese loess. Many efforts have been made to study its formation, age, and implications for paleo-environmental reconstruction. However, evidences from loess and paleosoil composition cannot give a unique solution to the source ascription of loess in East China, largely due to the intensitive secondary alteration on loess materials. Two views on the loess source are emerged: far-source and proximal-source.With the progress on study of Asian dust transportation and its potential source regions, indicators have been developed to trace the source regions of airborne dust. This new perspective, in combination with studies on loess, may provide an approach to solve the debatable views on loess sources in East China..In this study, eolian loess, airborne dust of Changjiang river delta and the potential source materials will be characterized by properties of mineralogy, granulometry and geochemistry to indentify the possible source indicators and to constrain the provenance of the East China eolian loess.The expected results may contribute to an understanding of loess formation and evolution in East China, enviromental change in arid and semiarid regions during glacial period,and changes in paleo-atmospheric circulation.

中国东部风尘黄土是中国黄土的重要组成部分，其成因、年代及古环境意义已有较多深入研究。但因其次生改造强烈，仅从黄土、古土壤角度分析物源存在不确定性，出现了"远源"和"近源"的不同看法。随着大气粉尘输送路径及物源研究的日益成熟，将风尘黄土和大气粉尘物源示踪研究结合，探索可靠的物源识别指标，是解决东部黄土物质来源问题的途径之一。本课题以长江三角洲风尘黄土、大气粉尘及潜在源区物质为研究对象，采用地球化学、矿物学、粒度等研究手段，分别探索风尘黄土、大气粉尘的物源识别指标，并运用"将今论古"的方法，将二者的识别指标对比分析，进一步研究中国东部风尘黄土物源识别指标及其物质来源。该研究成果对揭示中国东部黄土的形成和演化，探索冰期时期干旱-半干旱区环境格局的变动、古大气环流形势具有重要的科学意义。

对于长江三角洲风尘堆积的物质来源问题，一直存在着“远源”、“近源”的不同观点。本课题通过对比分析沙尘暴沙尘和风尘黄土理化特征，探索长江三角洲风尘黄土物质来源，这是一个新的视角和尝试。以长江三角洲大气粉尘和风尘黄土为研究对象，对比分析二者的地球化学、磁学、矿物学等特征，探讨长江三角洲风尘黄土物质来源识别指标及物质来源。研究发现，长江三角洲沙尘暴期间粉尘地球化学、磁学、矿物组成等特征均表现出与风尘黄土相似的特征，揭示出沙尘暴沙尘与黄土物源具较好的相似性。磁学参数Xlf、主量元素组成（如Mg/Al比值）及稀土元素配分模式等可能是沙尘暴沙尘及黄土物源示踪的良好方法和指标。该项研究能为探索长江三角洲地区乃至中国东部风尘堆积的物质来源提供较好的数据支撑，对于长江三角洲和中国东部古环境演变研究具有较高的科学价值。