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Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g., kaolin, Al 2 Si 2 O 5 4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. [1]
In much of Alberta and Saskatchewan, the "Second White-Specked Shale" contains limy equivalents of the Greenhorn. [3] In Kansas, the Greenhorn Formation is divided into the (lowest) Lincoln Limestone, Hartland Shale, Jetmore Chalk, and (highest) Pfeifer shale members, each noted by changes in chalkiness and limestone rhythmite patterns. [4]
Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain thin beds of conglomerate , marl , limestone , or some combination of these sedimentary rocks.
Two recognized types of intraformational conglomerates are shale-pebble and flat-pebble conglomerates. [6] A shale-pebble conglomerate is a conglomerate that is composed largely of clasts of rounded mud chips and pebbles held together by clay minerals and created by erosion within environments such as within a river channel or along a lake ...
The Bright Angel Shale consists of locally fossiliferous, green and red-brown, micaceous, fissile shale (mudstone) and siltstone with local, thicker beds of brown to tan sandstone and limestone. It ranges in thickness from 57 to 450 ft (17 to 137 m). Typically, its thin-bedded shales and sandstones are interbedded in cm-scale cycles.
The Marcellus Formation or the Marcellus Shale is a Middle Devonian age unit of sedimentary rock found in eastern North America.Named for a distinctive outcrop near the village of Marcellus, New York, in the United States, [3] it extends throughout much of the Appalachian Basin.
The effect of bioturbation has been documented well in shale cores sampled: past variable critical depths where burrowing organisms can no longer survive, shale fissility will become more pervasive and better defined. Fissility is used by some geologists as the defining characteristic which separates mudstone (no fissility) from shale (fissile ...
Oil shale geology is a branch of geologic sciences which studies the formation and composition of oil shales–fine-grained sedimentary rocks containing significant amounts of kerogen, and belonging to the group of sapropel fuels. [1] Oil shale formation takes place in a number of depositional settings and has considerable compositional variation.