关键词: 石英颗粒表面结构, 氧化硅, 图版, 中国黄土, 形成者, 贝壳状断口, 沉淀层, 化学结构, 矿物颗粒, 解理面

Abstract: Owing to hardness of quartz, the surface texture of grains produced during thier formation, transportation and deposition remains for a long time. It may be used as an evidence for illustrating the origin of loess.The surface texture of quartz grains may be divided into two types梞echanical and chemical. The former was formed during the formation and transportation of grains, while the latter, mainly formed during deposition. Mechanical texture includes cleavage planes, conchoidal fractures, pits, grooves with round and smooth bottom, broken fissures, pitted surface texture, etc. They might be formed in different environmental processes, but most of them show some evident marks of aeolian transportation, such as the abrasion of blown sand on the edges and surface as wall as at the groove bottom of the quartz grains.As for the chemical texture, it might have been subjected to weathering in situ especially in the process of deposition. Chief chemical texture includes silica precipitates, chemical etching and dissolution phenomena, such as round pits, triangular pits, pits with lid, convex parts in different shapes, etc.The surface texture of silt quartz grains shows that the formation of the loess materials might have passed through different processes, but the wind action is supposed to have played an important role during transportation.On the basis of the study of surface texture of quartz grains, it may be considered that the genesis of loess in China are due to multi-factors but the chief one being aeolian.