Breccia (pronounced /ˈbrɛtʃiə, ˈbrɛʃiə/, Italian: breach) is a rock composed of angular fragments of rocks or minerals in a matrix, that is a cementing material, that may be similar or different in composition to the fragments. Italian ( or lingua italiana) is a Romance language spoken by about 63 million people as a First language, primarily in Italy. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific The matrix or groundmass of rock is the fine-grained mass of material in which larger grains or Crystals are embedded A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia, tectonic breccia, igneous breccia, impact breccia and hydrothermal breccia. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) This article discusses the geologic usage for the philosophical or architectural usage see Architectonics ' Or see Plate tectonics. Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock Hydrothermal circulation in its most general sense is the circulation of hot water 'hydros' in the Greek meaning water and 'thermos' meaning heat
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Nomenclature
Breccias can be classified by their constituents, mode of occurrence, constituent fragment size, the types of clasts and source of clasts. Clastic rocks are composed of fragments or clasts, of pre-existing rock. Several textural terms are used to describe the morphology and textural variations observed in breccias. Rock microstructure includes the texture of a rock and the small scale rock structures
Milling
Breccias which are formed by injection of a slurry (be it as a hydrofracture breccia or, more usually, a volcanic or intrusive breccia) often show evidence of rounding of the clasts. With a sedimentary rock this may be called a conglomerate, except when the breccia is discordant with former lithology (clastic dike). Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) In Geology, petrology (from Greek πέτρα petra, rock and λόγος logos, knowledge is the study of rocks and the conditions on which A clastic dike is the geological term used to describe a seam of 'foreign' sedimentary material (often Breccia) that fills cracks in sedimentary strata For an intrusive breccia, erosion and transport in a watercourse cannot be invoked to explain rounding. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Breccias of this type which are rounded are said to be milled, a process by which the breccia matrix grinds the larger clasts and rounds them off. This has been observed to have occurred in some hydrothermal breccias.
Autobrecciation
Autobrecciation is the process by which a rock's mechanism of formation causes it to become broken and to include its broken fragments within itself. This is properly explained in the section on lava (Volcanic breccias). Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures
Types
Sedimentary
Sedimentary breccias are a type of clastic sedimentary rock which are composed of angular to subangular, randomly oriented clasts of other sedimentary rocks. Clastic rocks are composed of fragments or clasts, of pre-existing rock. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Clastic rocks are composed of fragments or clasts, of pre-existing rock. They are formed by either submarine debris flows, avalanches, mud flow or mass flow in an aqueous medium. Debris flows are often referred to as mudslides Mudflows jökulhlaups, or debris Avalanches. This article refers to the natural event For other uses see Avalanche (disambiguation An avalanche is an abrupt and rapid flow of snow often Mudslide redirects here it is also the name of a cocktail. A mudflow or mudslide is the most rapid (up to 80 km/h / 50 mph Technically, turbidites are a form of debris flow deposit and are a fine-grained peripheral deposit to a sedimentary breccia flow. Turbidite Geological formations have their origins in Turbidity current deposits, which are deposits from a form of underwater Avalanche that
The other derivation of sedimentary breccia is as angular, poorly sorted, very immature fragments of rocks in a finer grained groundmass which are produced by mass wasting. These are, in essence, lithified colluvium. Colluvium is the name for loose bodies of Sediment that have been deposited or built up at the bottom of a low-grade slope or against a barrier on that slope transported by Thick sequences of sedimentary (colluvial) breccias are generally formed next to fault scarps in grabens. A graben is a depressed block of land bordered by parallel faults Graben is German for ditch.
In the field, it may at times be difficult to distinguish between a debris flow sedimentary breccia and a colluvial breccia, especially if one is working entirely from drilling information. Drilling is the process of using a Drill bit in a Drill to produce cylindrical holes in solid materials such as wood or metal Sedimentary breccias are an integral host rock for many SEDEX ore deposits. Sedimentary exhalative deposits (abbreviated as SEDEX from SED imentary EX halative are Ore deposits which are interpreted to have been formed by release
Sedimentary breccias can be described as 'arenaceous', from the Latin word harena meaning 'sand', which are sandy or pebbly in nature. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles A pebble is a clast of rock with a Particle size of 4 to 64 Millimeters based on the Krumbein phi scale of Sedimentology
A conglomerate by contrast is a sedimentary rock composed of rounded fragments or clasts of pre-existing rocks. A conglomerate (kɒnˈglɒmərət is a rock consisting of individual stones that have become cemented together Both breccias and conglomerates are composed of fragments averaging greater than 2 millimeters in size. The angular shape of the fragments indicate that the material has not been transported far from its source. Breccias indicate accumulation in a juvenile stream channel or accumulations because of gravity erosion. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Talus slopes might become buried and the talus cemented in a similar manner. Scree, also called talus and detritic cone, is a term given to broken rock that appears at the bottom of Crags mountain Cliffs or
Collapse
Collapse breccias form where there has been a collapse of rock, typically in a karst landscape. Karst topography is a landscape shaped by the dissolution of a layer or layers of soluble Bedrock, usually Carbonate rock such as Limestone Collapse breccias form blankets in highly weathered regolith due to the removal of rock components by dissolution. Regolith ( Greek: "blanket rock" is a layer of loose Heterogeneous material covering solid rock. Solvation, commonly called dissolution, is the process of attraction and association of Molecules of a Solvent with molecules or Ions of a
Tectonic
Tectonic breccias form where two tectonic plates create a crumbling of the interface, by their relative movements. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere
Fault
Fault breccias result from the grinding action of two fault blocks as they slide past each other. In Geology a fault, or fault line, is a planar rock fracture which shows evidence of relative movement Subsequent cementation of these broken fragments may occur by means of mineral matter introduced by groundwater. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Groundwater is Water located beneath the Ground surface in Soil pore spaces and in the Fractures of lithologic formations
Igneous
Igneous clastic rocks can be divided into two classes
- Broken, fragmental rocks associated with volcanic eruptions, both of lava and pyroclastic type
- Broken, fragmental rocks produced by intrusive processes, usually associated with plutons or porphyry stocks
Volcanic
Volcanic pyroclastic rocks are formed by explosive eruption of lava and any rocks which are entrained within the eruptive column. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire and κλαστός, meaning broken are Clastic rocks In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. Porphyry is a variety of Igneous rock consisting of large-grained Crystals such as Feldspar or Quartz, dispersed in a fine-grained Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire and κλαστός, meaning broken are Clastic rocks Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures This may include rocks plucked off the wall of the magma conduit, or physically picked up by the ensuing pyroclastic surge. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet A pyroclastic surge is a fluidized mass of turbulent gas and rock fragments which is ejected during some Volcanic eruptions It is similar to a Pyroclastic flow but Lavas, especially rhyolite and dacite flows, tend to form clastic volcanic rocks by a process known as autobrecciation. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures This page is about a volcanic rock For the ghost town see Rhyolite Nevada, and for the satellite system see Rhyolite/Aquacade. Dacite ( deɪsaɪt) is an igneous, volcanic rock with a high iron content This occurs when the thick, nearly solid lava breaks up into blocks and these blocks are then reincorporated into the lava flow again and mixed in with the remaining liquid magma. The resulting breccia is uniform in rock type and chemical composition.
Lavas may also pick up rock fragments, especially if flowing over unconsolidated rubble on the flanks of a volcano, and these form volcanic breccias, also called pillow breccias.
The volcanic breccia environment is transitional into the plutonic breccia environment in the volcanic conduits of explosive volcanoes, where lava tends to solidify and may be repeatedly shattered by ensuing eruptions. A pluton in Geology is an Intrusive Igneous rock body that crystallized from a Magma slowly cooling below the surface of the Earth This is typical of volcanic caldera settings. A caldera is a cauldron-like volcanic feature formed by the collapse of land following a volcanic eruption
Intrusive
Clastic rocks are also commonly found in shallow subvolcanic intrusions such as porphyry stocks, granites and kimberlite pipes, where they are transitional with volcanic breccias. In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. Kimberlite is a type of potassic Volcanic rock best known for sometimes containing Diamonds It is named after the town of Kimberley in South Africa [1]
Intrusive rocks can become brecciated in appearance by multiple stages of intrusion, especially if fresh magma is intruded into partly consolidated or solidified magma. This may be seen in many granite intrusions where later aplite veins form a late-stage stockwork through earlier phases of the granite mass. In Geology, a vein is a finite volume within a rock, having a distinct shape filled with Crystals of one or more Minerals which were precipitated In Geology, a stockwork is a complex system of structurally controlled or randomly oriented veins. When particularly intense, the rock may appear as a chaotic breccia.
Clastic rocks in mafic and ultramafic intrusions are known and form via several processes;
- consumption and melt-mingling with wall rocks, where the felsic wall rocks are softened and gradually invaded by the hotter ultramafic intrusion (termed taxitic texture by Russian geologists)
- Accumulation of rocks which fall through the magma chamber from the roof, forming chaotic remnants
- Autobrecciation of partly consolidated cumulate by fresh magma injections or by violent disturbances within the magma chamber (e. Mafic is an adjective describing a Silicate mineral or rock that is rich in magnesium and iron the term was derived by contracting "magnesium" and "ferric" Ultramafic (also referred to as ultrabasic) rocks are igneous and meta -igneous rocks with very low Silica content (less than 45% generally Cumulate rocks are Igneous rocks formed by the accumulation of Crystals from a Magma either by settling or floating g. postulated earthquakes)
- Accumulation of xenoliths within a feeder conduit or vent conduit
Impact
Impact breccias are thought to be diagnostic of an impact event such as an asteroid or comet striking the Earth, and are usually found at impact craters. An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer This article concerns the geologic term for other uses see Xenolith (disambiguation A xenolith ( Greek: 'foreign rock' is a rock See also Impact crater An impact event is the Collision of a large Meteoroid, Asteroid or Comet (generically Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body
Impact breccia, a type of impactite, forms during the process of impact cratering when large meteorites or comets impact with the Earth or other rocky planets or asteroids. Impactite is an informal term describing a rock created or modified by the impact of a Meteorite. In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but Breccia of this type may be present on or beneath the floor of the crater, in the rim, or in the ejecta expelled beyond the crater. Impact breccia may be identified by its occurrence in or around a known impact crater, and/or an association with other products of impact cratering such as shatter cones, impact glass, shocked minerals, and chemical and isotopic evidence of contamination with extraterrestrial material (e. Shatter cones are rare geological features that are only known to form in the bedrock beneath Meteorite impact craters or underground nuclear explosions Shocked quartz is a form of Quartz that has a microscopic structure that is different from normal quartz A chemical substance is a Material with a definite chemical composition. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides g. iridium and osmium anomalies). The term iridium anomaly commonly refers to an unusual abundance of the Chemical element Iridium in a layer of rock strata, often taken as evidence of an Osmium (ˈɒzmiəm is a Chemical element that has the symbol Os and Atomic number 76
Hydrothermal
Hydrothermal breccias usually form at shallow crustal levels (<1 km) between 150 to 350oC, when seismic activity (an earthquake) causes a void to open along a fault deep underground. In Geology, a crust is the outermost solid shell of a planet or moon An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer The void draws in hot water and as pressure in the cavity drops, the water violently boils - akin to an underground geyser. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Boiling (also called ebullition) a type of Phase transition, is the rapid vaporization of a Liquid, which typically occurs when a liquid A geyser is a Hot spring characterized by intermittent discharge of water ejected turbulently and accomplished by a vapour phase In addition, the sudden opening of a cavity causes rock at sides of the fault to destabilise and implode inwards, the broken rock gets caught up in a churning mixture of rock, steam and boiling water. Uses A Steam engine uses the expansion of steam in order to drive a Piston or Turbine to perform Mechanical work. Boiling (also called ebullition) a type of Phase transition, is the rapid vaporization of a Liquid, which typically occurs when a liquid Rock fragments hit each other and sides of the fault, and attrition quickly rounds angular breccia fragments. Volatile gases are lost to the steam phase as boiling continues, in particular CO2. In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single As a result, the chemistry of the fluids change and ore minerals rapidly precipitate. FLUID ( F ast L ight '''U'''ser '''I'''nterface D esigner is a graphical editor that is used to produce FLTK Source code An ore is a volume of rock containing components or Minerals in a mode of occurrence that renders it valuable for mining Precipitation is the formation of a Solid in a Solution during a Chemical reaction.
Breccia-hosted ore deposits are ubiquitous. An ore is a volume of rock containing components or Minerals in a mode of occurrence that renders it valuable for mining [2]
The morphology of breccias associated with ore deposits varies from tabular sheeted veins and clastic dikes associated with overpressured sedimentary strata, to large-scale intrusive diatreme breccias, or even some synsedimentary diatremes formed solely by the overpressure of pore fluid within sedimentary basins. The various theories of ore genesis explain how the various types of mineral deposits form within the Earth's crust. A diatreme is a breccia filled Volcanic pipe that was formed by a gaseous explosion The term sedimentary basin is used to refer to any geographical feature exhibiting Subsidence and consequent infilling by sedimentation Hydrothermal breccias are usually formed by hydrofracturing of rocks by highly pressured hydrothermal fluids. Hydrothermal circulation in its most general sense is the circulation of hot water 'hydros' in the Greek meaning water and 'thermos' meaning heat They are typical of the epithermal ore environment and are intimately associated with intrusive-related ore deposits such as skarns, greisens and porphyry-related mineralisation. The neutron temperature, also called the neutron energy, indicates a free neutron's Kinetic energy, usually given in Electron volts The term Skarn is a Metamorphic rock that is usually variably colored green or red occasionally grey black brown or white Greisen is a highly altered granitic rock or Pegmatite. Greisen is formed by autogenic alteration of a granite and is a class of endoskarn. Porphyry is a variety of Igneous rock consisting of large-grained Crystals such as Feldspar or Quartz, dispersed in a fine-grained Epithermal deposits are mined for copper, silver and gold. Mining is the extraction of valuable Minerals or other geological materials from the earth usually (but not always from an Ore body Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79
In the mesothermal regime, at much greater depths, over-pressured fluids under lithostatic pressure can be released during seismic activity associated with mountain building. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface The pressurised fluids ascend towards shallower crustal levels that are under lower hydrostatic pressure. Fluid pressure is the Pressure at some point within a Fluid, such as water or air On their journey, high-pressure fluids crack rock by hydrofracturing, forming an angular jigsaw breccia. Rounding of rock fragments less common in the mesothermal regime, as the formational event is brief. If boiling occurs, methane and hydrogen sulfide may be lost to the steam phase and ore may precipitate. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Hydrogen sulfide (or hydrogen sulphide) is the Chemical compound with the formula H 2 S. Mesothermal deposits are often mined for gold. Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79
Ornamental uses
The striking visual appearance of breccias has for millennia made them a popular sculptural and architectural material. Ancient Egypt was an Ancient Civilization in eastern North Africa, concentrated along the lower reaches of the Nile River in what is now The term architecture (from Greek αρχιτεκτονικήarchitektoniki) can be used to mean a process a profession or documentation Breccia was employed for column bases in the Minoan palace of Knossos on Crete in about 1800 BC. A palace is a grand residence especially the home of a Head of state or some other high-ranking Public figure. Knossos (alternative spellings Knossus, Cnossus, Greek Κνωσός kno̞ˈso̞s also known as the Knossos Palace is the largest [3] Breccia was used on a limited scale by the ancient Egyptians - one of the best-known examples is the statue of the goddess Tawaret in the British Museum). Ancient Egypt was an Ancient Civilization in eastern North Africa, concentrated along the lower reaches of the Nile River in what is now The British Museum is a Museum of human history and culture in London. It was regarded by the Romans as an especially precious stone and was often used in high-profile public buildings. Ancient Rome was a Civilization that grew out of a small agricultural community founded on the Italian Peninsula as early as the 10th century BC A gemstone or gem, also called a precious or semi-precious stone, is a piece of attractive Mineral, which &mdash when cut and polished &mdash Many types of marble are brecciated, such as Breccia Oniciata or Breche Nouvelle. Marble is a nonfoliated Metamorphic rock resulting from the Metamorphism of Limestone, composed mostly of Calcite (a crystalline form of
It is most often used as an ornamental or facing material in walls and columns. A particularly striking example can be seen in the Pantheon in Rome, which features two gigantic columns of pavonazzetto, a breccia coming from Phrygia (in modern Turkey). The Pantheon ( Latin Pantheon, from Greek Πάνθειον Pantheon, meaning "Temple of all the gods" is a building in Rome In antiquity Phrygia (Φρυγία was a kingdom in the west central part of Anatolia, in what is now modern-day Turkey. Turkey (Türkiye known officially as the Republic of Turkey ( is a Eurasian Country that stretches Pavonazzetto obtains its name from its extremely colourful appearance, which is reminiscent of a peacock's feathers (pavone is "peacock" in Italian). The term peafowl refers to Gallinaceous Birds classified within the genera Rheinardia Argusianus Afropavoand Pavo Italian ( or lingua italiana) is a Romance language spoken by about 63 million people as a First language, primarily in Italy.
See also
Line note references
- ^ T.W.Mitcham, Origin of breccia pipes, American Journal of Science, volume 69, pages 412-413 (1974)
- ^ Michel Jébrak, Hydrothermal breccias in vein-type ore deposits: A review of mechanisms, morphology and size distribution, Ore Geology Reviews, volume 12, pages 111-134 (1997)
- ^ C. Michael Hogan, Knossos fieldnotes, Modern Antiquarian (2007)
Bibliography
Sibson, R. In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body Hydrothermal circulation in its most general sense is the circulation of hot water 'hydros' in the Greek meaning water and 'thermos' meaning heat In Geology, a vein is a finite volume within a rock, having a distinct shape filled with Crystals of one or more Minerals which were precipitated A diatreme is a breccia filled Volcanic pipe that was formed by a gaseous explosion Kimberlite is a type of potassic Volcanic rock best known for sometimes containing Diamonds It is named after the town of Kimberley in South Africa H. (1987). "Earthquake rupturing as a mineralizing agent in hydrothermal systems". Geology 15: 701-704.
Sibson, R. H. (2000). "Fluid involvement in normal faulting". Journal of Geodynamics 29: 469-499. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
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