Brazos River bar; a study in the significance of grain size parameters

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	Brazos River bar; a study in the significance of grain size parameters
	Robert Louis Folk ; and William C. Ward
刊名	Journal of Sedimentary Research
	1957
卷号	27 期号:1 页码:3--26
ISSN号	1527-1404
英文摘要	A bar on the Brazos River near Calvert, Texas, has been analyzed in order to determine the geologic meaning of certain grain size parameters and to study the behavior of the size fractions with transport. The bar consists of a strongly bimodal mixture of pebble gravel and medium to fine sand; there is a lack of material in the range of 0.5 to 2 mm, because the source does not supply particles of this size. The size distributions of the two modes, which were established in the parent deposits, are nearly invariant over the bar because the present environment of deposition only affects the relative proportions of the two modes, not the grain size properties of the modes themselves. Two proportions are most common; the sediment either contains no gravel or else contains about 60% gravel. Three sediment types with characteristic bedding features occur on the bar in constant stratigraphic order, with the coarsest at the base. Statistical analysis of the data is based on a series of grain size parameters modified from those of Inman (1952) to provide a more detailed coverage of non-normal size curves. Unimodal sediments have nearly normal curves as defined by their skewness and kurtosis. Non-normal kurtosis and skewness values are held to be the identifying characteristics of bimodal sediments even where such modes are not evident in frequency curves. The relative proportions of each mode define a systematic series of changes in numerical properties; mean size, standard deviation and skewness are shown to be linked in a helical trend, which is believed to be applicable to many other sedimentary suites. The equations of the helix may be characteristic of certain environments. Kurtosis values show rhythmic pulsations along the helix and are diagnostic of two-generation sediments.
公开日期	2010-12-27
内容类型	期刊论文
源URL	[http://ir.yic.ac.cn/handle/133337/3034]
专题	烟台海岸带研究所_科研共享资源
推荐引用方式 GB/T 7714	Robert Louis Folk,and William C. Ward. Brazos River bar; a study in the significance of grain size parameters[J]. Journal of Sedimentary Research,1957,27(1):3--26.
APA	Robert Louis Folk,&and William C. Ward.(1957).Brazos River bar; a study in the significance of grain size parameters.Journal of Sedimentary Research,27(1),3--26.
MLA	Robert Louis Folk,et al."Brazos River bar; a study in the significance of grain size parameters".Journal of Sedimentary Research 27.1(1957):3--26.