【摘要】 <正> 比重是物质的重要物性之一,是物质成分和结构的反映。不同矿物的比重可以相差若干倍,因而用以鉴定矿物的种类。在河流动力学有关基本原理和计算公式中,比重是一种重要的因素,在沉积岩石学中被视为沉积物的沉积三要素(粒度、比重和形状)之一。我们对滹沱河现代沉积物进行沉积构造、粒度、矿物成分和扫描电镜等项分析的同时,对沉积物的比重作了一些分析,探讨了沉积物的比重在河流沉积体系中的变化情况。更多还原

【Abstract】 After the analysis of the specific gravity of the modern sediments of the Hutuo River, the authors hold that specific gravity of sediments in channel facies,channel bar facies and point bar facies Inereases with the decrease of grain size along the river. As for the sediments in the natural levee facies, the specific gravity becomes smaller with the decrease of grain size from up-stream to down-stream. The specific gravity becomes smaller gradually with the decrease of grain size from the central part of the river to the banks in the cross section of the river along which the channel facies, channel bar facies, point bar facies and natural levee facies are well arranged in order. In the vertical section, just as described in this paper, the specific gravity of modern sediments varies in different sub-facies.Through this study, it shows that the types of specific gravity curve vary in different kinds of sedimentary sub-facies. Four models of specific gravity curve are found, i. e. Mountain Model, Slope Model, Hill Model and Plain Model which are related to channel facies, channel bar facies, point bar facies and natural levee facies, respectively. It also indicates that when the grain size at down-stream bec- omes smaller (between 3-4.5φ) , the larger difference of the specific gravity of various sub-facies may be clear. This phenomenon might be favourable for the study of river and that of fine sediments in lake and ocean as well.更多还原