Journal ArticleDOI
Brazos River bar [Texas]; a study in the significance of grain size parameters
Robert L. Folk,William C. Ward +1 more
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In this paper, 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.Abstract:
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.read more
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Journal ArticleDOI
GRADISTAT: a grain size distribution and statistics package for the analysis of unconsolidated sediments
Simon J. Blott,Kenneth Pye +1 more
TL;DR: GRADISTAT as discussed by the authors is a computer program for the rapid analysis of grain size statistics from any of the standard measuring techniques, such as sieving and laser granulometry.
Book
The Rock Physics Handbook: Tools for Seismic Analysis of Porous Media
TL;DR: In this article, the authors present basic tools for elasticity and Hooke's law, effective media, granular media, flow and diffusion, and fluid effects on wave propagation for wave propagation.
MonographDOI
The Rock Physics Handbook
TL;DR: The third edition of the reference book as discussed by the authors has been thoroughly updated while retaining its comprehensive coverage of the fundamental theory, concepts, and laboratory results, and highlights applications in unconventional reservoirs, including water, hydrocarbons, gases, minerals, rocks, ice, magma and methane hydrates.
Journal ArticleDOI
A review of the origin and characteristics of recent alluvial sediments
TL;DR: In this paper, the geometrical, textural, structural, and biological characteristics of alluvial sediments are reviewed with respect to their geometrically, texturally, structural and biological properties, which are related to the physiographic occurrence and hydraulic geometry of streams and to the dynamics of flowing water.
Journal ArticleDOI
A review of grain‐size parameters
TL;DR: A review of the many graphical and mathematical techniques that have been proposed for the statistical summary of grain-size data can be found in this paper, with a focus on the statistical summarization of grain data.
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