黄土高原黄土团粒组成及其与碳酸钙关系的研究

通过团粒分析、电子显微镜 (SEM/EDX)扫描等元素分析扫描方法和手段 ,对黄土高原西北部自然黄土中的团粒数量及其与碳酸钙的溶解量的关系、团粒表面和内部碳酸钙的分布进行了研究。结果表明 :碳酸钙大约参与了 99%的团粒形成 ,呈现团粒越大 ,碳酸钙含量越多的趋势 ;反之 ,团粒数量与碳酸钙的溶解量成反比 ;随着团粒表面碳酸钙分布的减少 ,附着在团粒表面的微团粒及粉粒、粘粒减少 ;在团粒内部 ,碳酸钙与矿物颗粒之间存在 3种胶结方式 ,分别为碳酸钙附着在矿物颗粒表面、碳酸钙分布于矿物颗粒之间以及碳酸钙表面附着矿物颗粒。实验结果证明了黄土团粒的主要胶结物是碳酸钙这一理论。

COMPOSITION OF LOESS AGGREGATE AND ITS RELATIONSHIP WITH CaCO3 ON THE LOESS PLATEAU

Natural loess in the northwest of the Loess Plateau was sampled, measured and studied for aggregate amount, relationship between the aggregates and CaCO 3 dissolution, composition of the aggregates, and CaCO 3 distribution on the surface and in the interior of the aggregates with aid of Scanning Election Micrograph (SEM). The results show that: CaCO 3 takes part in the formation of almost all aggregates; the bigger the aggregates are, the higher the CaCO 3 amount is. whereas the number of aggregates is inversely proportional to CaCO 3 dissolution amount. With decrease in CaCO 3 distribution on aggregate surface, the amounts of microaggregates, silts and clay attaching to the aggregate surface reduce. Inside the aggregate, there are three types of cementation between CaCO 3 and mineral particles: CaCO 3 is adsorbed to mineral particle surface, CaCO 3 distributes among mineral particles and mineral particles attach to CaCO 3 surface. The experimental results testify that the main cement of loess aggregates is CaCO 3.