汉江上游郧县辽瓦店剖面粒度组成特征及其意义

对汉江上游河谷辽瓦店（LWD）剖面的地层特征及粒度分布进行了研究，并与渭河河谷典型风成堆积物对比。结果表明：该剖面中黄土和古土壤的粒度组成以粗粉砂（10～50 μm）为主，频率曲线图、三角图、参数结构散点图等均指示它们具有相同的物质来源，但明显区别于洪水滞流沉积物;其地层序列、宏观特征和粒度分布与渭河河谷全新世黄土-古土壤序列具有良好的可比性。LWD剖面的黄土和古土壤具有风成的基本特性，但其粒度组成比渭河河谷黄土整体偏细，这可能与沙尘暴越过秦岭后强度减弱有关。

Grain-size Distribution and its Significance in Liaowadian Profile in the Upper Hanjiang River Valley, China

The Liaowadian profile in the first level river terraces of the upper Hanjiang River valley was surveyed in detail, and then sampled systematically. Profile structure was observed in the field. Grain size distribution was analyzed in laboratory and compared with aeolian deposit in the Weihe River valley. An integration of the results shows that the loess and paleosol (S0) in the LWD profile were composed mainly of coarse silt (10-50 μm), and the loess and paleosol (S0) fall in the same area in the grain frequency curves, grain triangular diagram and grain parameter structure scatter diagram. It suggests that loess and paleosol (S0) have the same material source, but different from those of the slackwater deposits (SWD). They are the same as the Holocene loess-paleosol sequences in the Weihe River valley in stratigraphic structure, macroscopic characteristics and grain-size distribution. It indicates that the loess and paleosol (S0) from the LWD profile have aeolian features. Average loess grain size of the LWD profile is more finer than those in the Weihe River valley because dust storm activity decreased after it across the Qinling Mountains.