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Country Rock (geology)
In geology, country rock is the rock native to an area, in contrast to any intrusion of viscous geologic material, commonly magma, or perhaps rock salt (in salt domes) or unconsolidated sediments. Magma is typically less dense than the rock it intrudes, widening and filling existing cracks, sometimes melting the already-existing country rock. The term "country rock" is similar to, and in many cases interchangeable with, the terms basement and wall rocks. Country rock can denote the widespread lithology of a region in relation to the rock which is being discussed or observed. Geologic settings Settings in geology when the term ''country rock'' is used include: Igneous intrusions When describing a pluton or dike, the igneous rock can be described as intruding the surrounding ''country rock'', the rock into which the pluton has intruded.Newfoundland and LabradorGlossary of Geological Terms Accessed June 2018. When country rock is intruded by a dike, perpendicular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Country Rock Intruded
A country is a distinct part of the Earth, world, such as a state (polity), state, nation, or other polity, political entity. When referring to a specific polity, the term "country" may refer to a sovereign state, List of states with limited recognition, state with limited recognition, Country (other)#Administrative divisions, constituent country, or dependent territory. Most sovereign states, but not all countries, are members of the United Nations. There is no universal agreement on List of sovereign states, the number of "countries" in the world, since several states have disputed sovereignty status or limited recognition, and a number of non-sovereign entities are commonly considered countries. The definition and usage of the word "country" are flexible and have changed over time. ''The Economist'' wrote in 2010 that "any attempt to find a clear definition of a country soon runs into a thicket of exceptions and anomalies." Areas much smaller than a political entit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sill (geology)
In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock. A sill is a ''concordant intrusive sheet'', meaning that it does not cut across preexisting rock beds. Stacking of sills builds a sill complex. and a large magma chamber at high magma flux. In contrast, a dike is a discordant intrusive sheet, which does cut across older rocks. Formation Sills are fed by dikes, except in unusual locations where they form in nearly vertical beds attached directly to a magma source. The rocks must be brittle and fracture to create the planes along which the magma intrudes the parent rock bodies, whether this occurs along preexisting planes between sedimentary or volcanic beds or weakened planes related to foliation in metamorphic rock. These planes or weakened areas allow the intrusion of a thin sheet-like body of magma paralleling the existi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacier
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land“Glacier, N., Pronunciation.” Oxford English Dictionary, Oxford UP, June 2024, https://doi.org/10.1093/OED/7553486115. Accessed 25 Jan. 2025. and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions, but glaciers may be found in mountain ranges on ever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcano
A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes resulting from divergent tectonic activity are usually non-explosive whereas those resulting from convergent tectonic activity cause violent eruptions."Mid-ocean ridge tectonics, volcanism and geomorphology." Geology 26, no. 455 (2001): 458. https://macdonald.faculty.geol.ucsb.edu/papers/Macdonald%20Mid-Ocean%20Ridge%20Tectonics.pdf Volcanoes can also form where there is str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alluvium
Alluvium (, ) is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is typically geologically young and is not Consolidation (geology), consolidated into solid rock. Sediments deposited underwater, in seas, estuaries, lakes, or ponds, are not described as alluvium. Floodplain alluvium can be highly fertile, and supported some of the earliest human civilizations. Definitions The present Scientific consensus, consensus is that "alluvium" refers to loose sediments of all types deposited by running water in floodplains or in alluvial fans or related landforms. However, the meaning of the term has varied considerably since it was first defined in the French dictionary of Antoine Furetière, posthumously published in 1690. Drawing upon concepts from Roman law, Furetière defined ''alluvion'' (the French term for al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skarn
Skarns or tactites are coarse-grained metamorphic rocks that form by replacement of carbonate-bearing rocks during regional or contact metamorphism and metasomatism. Skarns may form by metamorphic recrystallization of impure carbonate protoliths, bimetasomatic reaction of different lithologies, and infiltration metasomatism by magmatic- hydrothermal fluids. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate minerals.Ray, G.E., and Webster, I.C.L. (1991): An Overview of Skarn Deposits; in Ore Deposits, Tectonics and Metallogeny in the Canadian Cordillera; McMillan, W.J., compiler, B. C. Ministry of Energy, Mines and Petroleum Resources, Paper 1991-4, pages 213-252.Meinert, L.D., 1992. Skarns and Skarn Deposits; Geoscience Canada, Vol. 19, No. 4, p. 145-162.Hammarstrom, J.M., Kotlyar, B.B., Theodore, T.G., Elliott, J.E., John, D.A., Doebrich, J.L., Nash, J.T., Carlson, R.R., Lee, G.K., Livo, K.E., Klein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hornfels
Hornfels is the group name for a set of Metamorphism#Contact .28thermal.29, contact metamorphic rocks that have been baked and hardened by the heat of Intrusive rock, intrusive igneous masses and have been rendered massive, hard, splintery, and in some cases exceedingly tough and durable. These properties are caused by fine grained non-aligned crystals with platy or prismatic Crystal habit, habits, characteristic of metamorphism at high temperature but without accompanying deformation. The term is derived from the German word ''Hornfels'', meaning "hornstone", because of its exceptional toughness and texture both reminiscent of animal horns. These rocks were referred to by miners in northern England as Sharpening stone, whetstones. Most hornfels are fine-grained, and while the original rocks (such as sandstone, shale, slate and limestone) may have been more or less fissile owing to the presence of bedding or Cleavage (geology), cleavage planes, this structure is effaced or rendered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphism
Metamorphism is the transformation of existing Rock (geology), rock (the protolith) to rock with a different mineral composition or Texture (geology), texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chemically active fluids, but the rock remains mostly solid during the transformation. Metamorphism is distinct from weathering or diagenesis, which are changes that take place at or just beneath Earth's surface. Various forms of metamorphism exist, including Regional metamorphism, regional, Contact metamorphism, contact, Hydrothermal metamorphism, hydrothermal, Shock metamorphism, shock, and Dynamic metamorphism, dynamic metamorphism. These differ in the characteristic temperatures, pressures, and rate at which they take place and in the extent to which reactive fluids are involved. Metamorphism occurring at increasing pressure and temperature conditions is known as ''prograde metamorphism'', while decreasin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Language
Greek (, ; , ) is an Indo-European languages, Indo-European language, constituting an independent Hellenic languages, Hellenic branch within the Indo-European language family. It is native to Greece, Cyprus, Italy (in Calabria and Salento), southern Albania, and other regions of the Balkans, Caucasus, the Black Sea coast, Asia Minor, and the Eastern Mediterranean. It has the list of languages by first written accounts, longest documented history of any Indo-European language, spanning at least 3,400 years of written records. Its writing system is the Greek alphabet, which has been used for approximately 2,800 years; previously, Greek was recorded in writing systems such as Linear B and the Cypriot syllabary. The Greek language holds a very important place in the history of the Western world. Beginning with the epics of Homer, ancient Greek literature includes many works of lasting importance in the European canon. Greek is also the language in which many of the foundational texts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenolith
A xenolith ("foreign rock") is a rock (geology), rock fragment (Country rock (geology), country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusively used to describe inclusion (mineral), inclusions in igneous rock entrained during magma ascent, emplacement and eruption. Xenoliths may be engulfed along the margins of a magma chamber, torn loose from the walls of an erupting lava conduit or explosive diatreme or picked up along the base of a flowing body of lava on the Earth's surface. A xenocryst is an individual foreign crystal included within an igneous body. Examples of xenocrysts are quartz crystals in a silica-deficient lava and diamonds within kimberlite diatremes. Xenoliths can be non-uniform within individual locations, even in areas which are spatially limited, e.g. rhyolite-dominated lava of Nii-jima, Niijima volcano (Japan) contains two types of gabbroic xenoliths which a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overlying Rock
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the location where the curvature is greatest, and the limbs are the sides of the fold that dip away from the hinge. Anticlines can be recognized and differentiated from antiforms by a sequence of rock layers that become progressively older toward the center of the fold. Therefore, if age relationships between various rock strata are unknown, the term antiform should be used. The progressing age of the rock strata towards the core and uplifted center, are the trademark indications for evidence of anticlines on a geological map. These formations occur because anticlinal ridges typically develop above thrust faults during crustal deformations. The uplifted core of the fold causes compression of strata that preferentially erodes to a deeper str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture (geology)
A fracture is any separation in a geologic formation, such as a Joint (geology), ''joint'' or a Fault (geology), ''fault'' that divides the Rock (geology), rock into two or more pieces. A fracture will sometimes form a deep fissure or crevice in the rock. Fractures are commonly caused by Stress (physics), stress exceeding the rock strength, causing the rock to lose cohesion along its weakest plane. Fractures can provide Permeability (fluid), permeability for fluid movement, such as water or hydrocarbons. Highly fractured rocks can make good aquifers or Oil reservoir, hydrocarbon reservoirs, since they may possess both significant Permeability (fluid), permeability and fracture porosity. Brittle deformation Fractures are forms of brittle deformation. There are two types of primary brittle deformation processes. Tensile fracturing results in ''joints''. ''Shear fractures'' are the first initial breaks resulting from shear forces exceeding the cohesive strength in that plane. Aft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
