Search results
Results from the WOW.Com Content Network
Arkose (/ ˈ ɑːr k oʊ s,-k oʊ z /) or arkosic sandstone [1] is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. [ 2 ] [ 3 ] Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose.
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains, cemented together by another mineral. Sandstones comprise about 20–25% of all sedimentary rocks. [1] Most sandstone is composed of quartz or feldspar, because they are the most resistant minerals to the weathering processes at the Earth's ...
If the abundances of quartz, feldspars and rock fragments indicate that the rock is an arkose, a subarkose or a lithic arkose, one must then normalize the abundance of feldspars to 100% and attempt to identify the relative abundances of K-feldspars to plagioclase in the sample. If there is more plagioclase than there is K-feldspar, the rock is ...
Since it refers to grain size rather than chemical composition, the term is used for example in the classification of clastic carbonatic limestones, as the granulometrically equivalent term sandstone is not appropriate for limestone. Other arenites include sandstones, arkoses, greensands, and greywackes.
Grus is an accumulation of angular, coarse-grained fragments (particles of sand and gravel) resulting from the granular disintegration by the processes of chemical and mechanical weathering of crystalline rocks (most notably granitoids) generally in an arid or semiarid region. [1] Grus sand, when cemented into a sandstone, will form an arkose.
Arkose is a sand or sandstone with considerable feldspar content, derived from weathering and erosion of a (usually nearby) granitic rock outcrop. Some sands contain magnetite, chlorite, glauconite, or gypsum. Sands rich in magnetite are dark to black in color, as are sands derived from volcanic basalts and obsidian.
The following is a list of rock types recognized by geologists.There is no agreed number of specific types of rock. Any unique combination of chemical composition, mineralogy, grain size, texture, or other distinguishing characteristics can describe a rock type.
The Pebbly Arkose Formation is part of the Upper Karoo Group, overlies the Escarpment formation (in the Mid-Zambezi and Limpopo basins) [2] and the Angwa Sandstone Formation (in the Mana Pools and Cabora Bassa Basins) [3] and underlies the Forest Sandstone Formation. [4] The Pebbly Arkose has been correlated to the Elliot Formation of the Great ...