Sedimentary Component Analysis Of Aeolian And Hydraulic Sediments

The grain-size of sediments are controlled by the transporting medium, transporting mode,depositional environment and climate. Grain-size analysis is a useful way to reveal the information of atmospheric dynamics and depositional environment.Grain-size distributions of classic sediments of aeolian and hydraulic sedimentary system are analyzed using grain-size component analysis method. In the method, grain-size components are firstly portioned from its distribution with grain-size distribution function fitting. The frequency distribution of a specific component size parameter, such as modal size or mean size, of all components of studied sediments reflect the genetic differentiation of components with different origins in grain-size, which can be used as the base to classify origins of sedimentary components. Combined analysis of grain-size ranges, sorting degree and sedimentary facies allow determining the origins of sedimentary components.In aeolian sedimentary system, aeolian rolling sand, aeolian saltation sand, coarse suspension dust, fine suspension dust and pedogenic components are identified which are roughly defined by modal-size boundary of 250,50,15, and 2 um. Desert sand is generally composed of aeolian salatation and fine suspension dust components, which have a specific ratio of about 9:1. Rolling sand component is occasionally found in some desert sand. Loess is composed of an coarse suspension dust and fine suspension dust with a ratio of about 8:2 to 4:5. Fine suspension dust is the main component of aeolian sediments in ocean, but coarse dust and sand component can also be found.In hydraulic sedimentary system, suspension and saltation components are identified with modal size ranges of 250-1000, and 2-20μm respectively. Fluvial sediment is composed of isolated saltation and suspension components. The sediments in closed lake basins are dominated by a suspension silt-clay component with a small proportion of saltation sand. Alluvial sediment mostly inherits its original grain-size characters, and was obviously modified or sorted by water to preserve fluvial characteristics in grain-size distribution. Sediments in marginal sea are dominated by suspension component with some portion of saltation component. Due to above significant differences in grain-size and proportion, sedimentary components with different origins are clearly grouped on a size-proportion plot which can be used to identify the origin of a component and sediment.