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The geological origin of building stones
Published in John A. Hudson†, John W. Cosgrove, Understanding Building Stones and Stone Buildings, 2019
John A. Hudson†, John W. Cosgrove
Clastic rocks are the main type of sedimentary rock and are formed from fragments of other rocks (igneous, sedimentary or metamorphic) and are therefore regarded as secondary rocks. Fragments (clasts) of rock, loosened from their outcrop at the Earth’s surface by the processes of weathering and erosion, are transported to some basin or depression by water or wind (e.g., desert sands and volcanic tuffs) where the sediments are trapped. These become compacted and cemented as they are buried beneath younger sediments to form sedimentary rocks. As with igneous rocks, they are classified on the basis of Composition, e.g., sandstone which is composed mainly of quartz grains, and limestone which consists mainly of calcite, often in the form of shells and shell fragments, andGrain size, e.g., sandstone is classified according to grain size: very fine grains (silt-stones); coarser grains (sandstones); and very coarse grained consisting of quartz rich pebbles (conglomerates).
Sedimentary Petrology
Published in Supriya Sengupta, Introduction to Sedimentology, 2017
Unconsolidated sediments coarser than 2 mm are grouped under the term gravel. Indurated gravels are called conglomerates. Since gravel is classified as granule, pebble, cobble and boulder (see Table 3.1), these terms are often used as prefixes to indicate the size of the dominant fragments in a conglomerate (e.g., pebble conglomerate, boulder conglomerate). While the particles constituting a conglomerate are essentially rounded, a breccia consists of gravel-size clasts which are angular. The term rubble is applied to an assemblage of loose angular fragments of gravel size. Breccias need not be of sedimentary origin only. For example, fault breccias are produced by tectonic activity. Large, well-rounded particles of volcanic origin (volcanic bombs) constitute a rock called an agglomerate.
Our Earth, its minerals and ore bodies
Published in Odwyn Jones, Mehrooz Aspandiar, Allison Dugdale, Neal Leggo, Ian Glacken, Bryan Smith, The Business of Mining, 2019
Odwyn Jones, Mehrooz Aspandiar, Allison Dugdale, Neal Leggo, Ian Glacken, Bryan Smith
Sedimentary rocks typically form in areas of low to negative topographic relief with respect to sea level, where minerals, derived from pre-existing rocks, are subjected to weathering, transportation and eventual deposition and lithification. The pre-existing rocks may be igneous, metamorphic or sedimentary in origin. Sedimentary rocks are classified as clastic, chemical or organic. Clastic rocks are formed from the weathering of terrestrial rocks. The minerals and rock fragments from this process are transported by water, wind or ice over variable distances and finally deposited and lithified. Chemical sediments by contrast are developed as a result of precipitation from a fluid e.g. evaporites. Organic sediments are dominated by organic material e.g. shells, carbon.
Major, trace and rare earth element geochemistry of the Permian Lucaogou oil shales, eastern Junggar Basin, NW China: implications for weathering, provenance and tectonic setting
Published in Australian Journal of Earth Sciences, 2023
M. Zhao, Y. Liu, X. Jiao, D. Zhou, Z. Meng, Y. Yang
Major-element contents and/or ratios of clastic sediments are commonly used to discriminate the provenance of sedimentary rocks because they maintain stable chemical properties during deposition, transportation and diagenesis (Armstrong‐Altrin, 2015; Madhavaraju, 2015). Sugitani et al. (1996) proposed that the TiO2/Al2O3 ratios decrease from mafic to felsic igneous sources. In the TiO2/Al2O3vs Fe2O3/Al2O3 and TiO2/Al2O3vs TiO2/Al2O3 diagrams (Figure 7a, b), most samples plot around andesite source with a small number as granite. The Al2O3/TiO2 ratios of the samples in our study (J1, 20.07–30.78; J2, 21.13–49.13; S, 21.45–48.76) are close to those of felsic igneous rocks (21–70, Hayashi et al., 1997). In the Al2O3vs TiO2 and Zr vs TiO2 diagrams (Figure 7c, d), most samples plot in the field of felsic igneous rocks with a small number as intermediate igneous rocks.
Predicting mechanical properties and ultimate shear strength of gypsum, limestone and sandstone rocks using Vipulanandan models
Published in Geomechanics and Geoengineering, 2020
Wael Mahmood, Ahmed Mohammed, Saman HamaHussein
Sandstone is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains (Vipulanandan and Mohammed 2018). Most sandstone is composed of quartz or feldspar because these are the most common minerals in the Earth’s crust. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite (Bucksch 2013).
Diagenesis and hydrocarbon charging period in the Lower Cretaceous Bayingebi Formation, Hari sag, Yin`E Basin, Northern China
Published in Petroleum Science and Technology, 2023
Guangyuan Xing, Kai Qi, Zhanli Ren, Junping Cui, Ying Zhang, Guilin Yang
The clastic grains of sandstone are mainly composed of quartz, feldspar and rock debris. The highest content of quartz is 71.00%, the lowest content is 32.00%, and the average content is 50.67%. The highest content of feldspar is 15.00%, the lowest content is 6.00%, and the average content is 8.33%. The highest content of rock chips is 51.00%, the lowest content is 8.00%, and the average content is 23.83% (Figure 4).