Lithic sandstones, or lithic arenites, or litharenites, are sandstones with a significant (>5%) component of lithic fragments, though quartz and feldspar are usually present as well, along with some clayey matrix. Lithic sandstones can have a speckled (salt and pepper) or gray color, and are usually associated with one specific type of lithic fragment (i.e., igneous, sedimentary, or metamorphic).
Sandstone is a clastic sedimentary rock composed mainly of sand-sized mineral particles or rock fragments.
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar.
Feldspars (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth's continental crust by weight.
Tectonically, lithic sandstones often form in a wide variety sedimentary depositional environments (including fluvial, deltaic, and alluvial sediments) associated with active margins. This tectonic setting provides the source of the lithic fragments, either through arc volcanism, thin-skinned faulting, continental collisions, unroofing, and subduction roll-back.
A river delta is a landform that forms from deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or another river that cannot carry away the supplied sediment. The size and shape of a delta is controlled by the balance between watershed processes that supply sediment, and receiving basin processes that redistribute, sequester, and export that sediment. The size, geometry, and location of the receiving basin also plays an important role in delta evolution. River deltas are important in human civilization, as they are major agricultural production centers and population centers. They can provide coastline defense and can impact drinking water supply. They are also ecologically important, with different species' assemblages depending on their landscape position.
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of small particles and subsequent cementation of mineral or organic particles on the floor of oceans or other bodies of water at the Earth's surface. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus. Before being deposited, the geological detritus was formed by weathering and erosion from the source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers, which are called agents of denudation. Biological detritus was formed by bodies and parts of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies. Sedimentation may also occur as dissolved minerals precipitate from water solution.
Quartzite is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of iron oxide (Fe2O3). Other colors, such as yellow, green, blue and orange, are due to other minerals.
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lithology may refer to either a detailed description of these characteristics, or a summary of the gross physical character of a rock. Lithology is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of mapping and correlation between areas. In certain applications, such as site investigations, lithology is described using a standard terminology such as in the European geotechnical standard Eurocode 7.
Greywacke or graywacke is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lithic fragments set in a compact, clay-fine matrix. It is a texturally immature sedimentary rock generally found in Paleozoic strata. The larger grains can be sand- to gravel-sized, and matrix materials generally constitute more than 15% of the rock by volume. The term "greywacke" can be confusing, since it can refer to either the immature aspect of the rock or its fine-grained (clay) component.
Arkose is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose.
In geology, a mélange is a large-scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix. The mélange typically consists of a jumble of large blocks of varied lithologies. Both tectonic and sedimentary processes can form mélange.
A quartz arenite or quartzarenite is a sandstone composed of greater than 90% detrital quartz, with limited amounts of other framework grains and matrix. It can have higher-than-average amounts of resistant grains, like chert and minerals in the ZTR index.
Arenite is a sedimentary clastic rock with sand grain size between 0.0625 mm (0.00246 in) and 2 mm (0.08 in) and contain less than 15% matrix. The related adjective is arenaceous. The equivalent Greek-derived term is psammite, though this is more commonly used for metamorphosed sediments.
The Folk classification is a technical descriptive classification of sedimentary rocks devised by Robert L. Folk, an influential sedimentary petrologist and Professor Emeritus at the University of Texas.
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Geologists use the term clastic with reference to sedimentary rocks as well as to particles in sediment transport whether in suspension or as bed load, and in sediment deposits.
Lithic may refer to:
This glossary of geology is a list of definitions of terms and concepts relevant to geology, its sub-disciplines, and related fields. For other terms related to the Earth sciences, see Glossary of geography terms.
Lithic fragments, or lithics, are pieces of other rocks that have been eroded down to sand size and now are sand grains in a sedimentary rock. They were first described and named by Bill Dickinson in 1970. Lithic fragments can be derived from sedimentary, igneous or metamorphic rocks. A lithic fragment is defined using the Gazzi-Dickinson point-counting method and being in the sand-size fraction. Sand grains in sedimentary rocks that are fragments of larger rocks that are not identified using the Gazzi-Dickinson method are usually called rock fragments instead of lithic fragments. Sandstones rich in lithic fragments are called lithic sandstones.
The Gazzi-Dickinson method is a point-counting technique used in geology to statistically measure the components of a sedimentary rock, chiefly sandstone. The main focus part of the technique is counting all sand-sized components as separate grains, regardless of what they are connected to. Gazzi-Dickinson point counting is used in the creation of ternary diagrams, such as QFL diagrams.
Pseudomatrix, as defined by Bill Dickinson in 1970, is the term for lithic fragments that have been deformed to become a traditional sandstone matrix. This is formed when a lithic-rich sandstone is compacted. The compaction is usually more effective on the (typically) weaker lithic fragments in comparison to the stronger, coarser-grained framework grains.
A QFL diagram or QFL triangle is a type of ternary diagram that shows compositional data from sandstones and modern sands, point counted using the Gazzi-Dickinson method. The abbreviations used are as follows:
Igneous rocks are found in Bukit Timah, Woodlands, and Pulau Ubin island. Granite makes up the bulk of the igneous rock. Gabbro is also found in the area and is found in an area called Little Guilin, named for its resemblance to Guilin in Southern China. This area is in Bukit Gombak. Sedimentary rocks are found on the western part of Singapore, and is mainly made of sandstone and mudstones. It also includes the southwestern area. Metamorphic rocks are found in the northeastern part of Singapore, and also on Pulau Tekong, off the east coast of Singapore. The rocks are mainly made up of quartzite, and also make up the Sajahat Formation.
Minchinbury Sandstone is a component of the Wianammatta Group of sedimentary rocks in the Sydney Basin of eastern Australia.
The geology of Sweden is the regional study of rocks, minerals, tectonics, natural resources and groundwater in the country. The oldest rocks in Sweden date to more than 2.5 billion years ago in the Precambrian. Complex orogeny mountain building events and other tectonic occurrences built up extensive metamorphic crystalline basement rock that often contains valuable metal deposits throughout much of the country. Metamorphism continued into the Paleozoic after the Snowball Earth glaciation as the continent Baltica collided with an island arc and then the continent Laurentia. Sedimentary rocks are most common in southern Sweden with thick sequences from the last 250 million years underlying Malmö and older marine sedimentary rocks forming the surface of Gotland.
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