graded bedding


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graded bedding

[¦grād·əd ′bed·iŋ]
(geology)
A stratification in which each stratum displays a gradation in the size of grains from coarse below to fine above.
References in periodicals archive ?
The sedimentary structures noticed include laminations, cross bedding, ripple marks, burrows, liesgang rings (?) and graded bedding. The other geological features include Manganese (Mn) dendrites, quartz veins and fractures.
Fourth bed is brownish in color and has graded bedding, with fining upward sequence.
There are overall 6 smaller cycles of graded bedding (fining upward sequence).
and Migliorini, C.I., 1950, Turbidity currents as a cause of graded bedding: Journal of Geology, v.
Grainstone with graded bedding: a coarse-grained floatstone with fine (diameter less than 0.5 cm) rounded lithoclasts grades upwards into pure, well-sorted, fine-grained grainstone.
between beds 6 and 7, is marked by a distinct, strongly pyritized discontinuity surface overlain by bed 7 of skeletal grainstone with graded bedding. In complex I, marlstone dominates and grainstone interlayers and stromatoporoids are almost lacking.
Horizontal to slightly inclined burrows and graded bedding are found in some thin sections.
At places filaments exhibit bedding parallel orientation and graded bedding (Fig.
Graded bedding is obvious in this preferred orientation.
The lower part of a minicyclite is represented by fine-grained, often bioturbated, argillaceous pack- to wackestones with mottles of dispersed pyrite; upper--by variable sparitic limestones from varigrained floatstone to well-sorted, pyritized, fine-grained grainstone, sometimes with normally graded bedding. The proportion of grainstone gradually increases upwards.
The lower part of each minicyclite consists of a 20-50 cm thick layer of marlstone or argillaceous limestone, succeeded by nodular to wavy-bedded, varigrained, skeletal packstone or wackestone with uneven, pyritized discontinuity surfaces (hardgrounds), and tempestite interlayers of fine-grained grainstone (sometimes with normally graded bedding).