Granodiorite is a phaneritic-textured intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. According to the QAPF diagram, granodiorite has a greater than 20% quartz by volume, between 65% to 90% of the feldspar is plagioclase. A greater amount of plagioclase would designate the rock as tonalite. Granodiorite is felsic to intermediate in composition, it is the intrusive igneous equivalent of the extrusive igneous dacite. It contains a large amount of sodium and calcium rich plagioclase, potassium feldspar and minor amounts of muscovite mica as the lighter colored mineral components. Biotite and amphiboles in the form of hornblende are more abundant in granodiorite than in granite, giving it a more distinct two-toned or overall darker appearance. Mica may be present in well-formed hexagonal crystals, hornblende may appear as needle-like crystals. Minor amounts of oxide minerals such as magnetite and ulvöspinel, as well as some sulfide minerals may be present.
On average, the upper continental crust has the same composition as granodiorite. Granodiorite is a plutonic igneous rock, formed by intrusion of silica-rich magma, which cools in batholiths or stocks below the Earth's surface, it is only exposed at the surface after uplift and erosion have occurred. The name comes from two related rocks to which granodiorite is an intermediate: diorite; the gran- root comes from the Latin grānum for "grain", an English language derivative. Diorite is named after the contrasting colors of the rock. Plymouth Rock is a glacial erratic boulder of granodiorite; the Sierra Nevada mountains contain large sections of granodiorite. Granodiorite was quarried at Mons Claudianus in the Red Sea Governorate in eastern Egypt from the 1st century AD to the mid-3rd century AD. Much of the quarried stone was transported to Rome for use in major projects such as the Pantheon and Hadrian's Villa. Additionally, granodiorite was used for the Rosetta Stone. Granodiorite is most used as crushed stone for road building.
It is used as construction material, building facade, paving, as an ornamental stone. The Rosetta Stone is a stele made from granodiorite; the portico columns of the Pantheon in Rome are formed from single shafts of granodiorite, each 12 metres tall by 1.5 metres in diameter. List of rock types This article incorporates public domain material from the United States Geological Survey document: "Granodiorite definition".. Media related to Granodiorite at Wikimedia Commons
A dike or dyke, in geological usage, is a sheet of rock, formed in a fracture in a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed. An intrusive dike is an igneous body with a high aspect ratio, which means that its thickness is much smaller than the other two dimensions. Thickness can vary from sub-centimeter scale to many meters, the lateral dimensions can extend over many kilometres. A dike is an intrusion into an opening cross-cutting fissure, shouldering aside other pre-existing layers or bodies of rock. Dikes are high-angle to near-vertical in orientation, but subsequent tectonic deformation may rotate the sequence of strata through which the dike propagates so that the dike becomes horizontal. Near-horizontal, or conformable intrusions, along bedding planes between strata are called intrusive sills.
The term "sheet" is the general term for both sills. Sometimes dikes appear in swarms, consisting of several to hundreds of dikes emplaced more or less contemporaneously during a single intrusive event; the world's largest dike swarm is the Mackenzie dike swarm in Canada. Dikes form as either radial or concentric swarms around plutonic intrusives, volcanic necks or feeder vents in volcanic cones; the latter are known as ring dikes. Dikes can vary in texture and their composition can range from diabase or basaltic to granitic or rhyolitic, but on a global perspective the basaltic composition prevails, manifesting ascent of vast volumes of mantle-derived magmas through fractured lithosphere throughout Earth history. Pegmatite dikes comprise coarse crystalline granitic rocks - associated with late-stage granite intrusions or metamorphic segregations. Aplite dikes are sugary-textured intrusives of granitic composition; the term "feeder dike" is used for a dike. Magma flowed along out of the dike formed another feature.
In contrast to magmatic dikes, a sill is a magmatic sheet intrusion that forms within and parallel to the bedding of layered rock. Sedimentary dikes or clastic dikes are vertical bodies of sedimentary rock that cut off other rock layers, they can form in two ways: When a shallow unconsolidated sediment is composed of alternating coarse grained and impermeable clay layers the fluid pressure inside the coarser layers may reach a critical value due to lithostatic overburden. Driven by the fluid pressure the sediment forms a dike; when a soil is under permafrost conditions the pore water is frozen. When cracks are formed in such rocks, they may fill up with sediments; the result is a vertical body of sediment that cuts through a dike. Batholith Ring dike Fissure vent – Linear volcanic vent through which lava erupts Laccolith Runamo – A cracked dolerite dike in Sweden, for centuries held to be a runic inscription interpreted as a runic inscription. Dike swarm Sill
Intrusive rock is formed when magma crystallizes and solidifies underground to form intrusions, for example plutons, dikes, sills and volcanic necks. Intrusive rock forms within Earth's crust from the crystallization of magma. Many mountain ranges, such as the Sierra Nevada in California, are formed from large granite intrusions. Intrusions are one of the two ways igneous rock. Technically an intrusion is any formation of intrusive igneous rock. In contrast, an extrusion consists of extrusive rock. Large bodies of magma that solidify underground before they reach the surface of the crust are called plutons. Plutonic rocks form 7% of the Earth's current land surface. Coarse-grained intrusive igneous rocks that form at depth within the earth are called abyssal while those that form near the surface are called subvolcanic or hypabyssal. Intrusive structures are classified according to whether or not they are parallel to the bedding planes or foliation of the country rock: if the intrusion is parallel the body is concordant, otherwise it is discordant.
An intrusive suite is a group of plutons related in time and space.. Intrusions vary from mountain-range-sized batholiths to thin veinlike fracture fillings of aplite or pegmatite. Intrusions can be classified according to the shape and size of the intrusive body and its relation to the other formations into which it intrudes: Batholith: a large irregular discordant intrusion Chonolith: an irregularly-shaped intrusion with a demonstrable base Cupola: a dome-shaped projection from the top of a large subterranean intrusion Dike: a narrow tabular discordant body nearly vertical Laccolith: concordant body with flat base and convex top with a feeder pipe below Lopolith: concordant body with flat top and a shallow convex base, may have a feeder dike or pipe below Phacolith: a concordant lens-shaped pluton that occupies the crest of an anticline or trough of a syncline Volcanic pipe or volcanic neck: tubular vertical body that may have been a feeder vent for a volcano Sill: a thin tabular concordant body intruded along bedding planes Stock: a smaller irregular discordant intrusive Boss: a small stock A body of intrusive igneous rock which crystallizes from magma cooling underneath the surface of the Earth is called a pluton.
If the pluton is large, it may be called a stock. Intrusive rocks are characterized by large crystal sizes, as the individual crystals are visible, the rock is called phaneritic; this is as the magma cools underground, while cooling may be fast or slow, cooling is slower than on the surface, so larger crystals grow. If it runs parallel to rock layers, it is called a sill. If an intrusion makes rocks above rise to form a dome, it is called a laccolith. How deep-seated intrusions burst through the overlying strata causes intrusive rock to be recognized: Veins spread out into branches, or branchlike parts result from filled cracks, the high temperature is evident in how they alter country rock; as heat dissipation is slow, as the rock is under pressure, crystals form, no vitreous chilled matter is present. The intrusions did not flow. Contained gases could not escape through the thick strata, thus form cavities, which can be observed; because their crystals are of the rough equal size, these rocks are said to be equigranular.
There is no distinction between a first generation of large well-shaped crystals and a fine-grained ground-mass. The minerals of each have formed in a definite order, each has had a period of crystallization that may be distinct or may have coincided with or overlapped the period of formation of some of the other ingredients. Earlier crystals originated at a time when most of the rock was still liquid and are more or less perfect. Crystals are less regular in shape because they were compelled to occupy the spaces left between the already-formed crystals; the former case is said to be idiomorphic. There are many other characteristics that serve to distinguish the members of these two groups. For example, orthoclase is feldspar from granite, while its modifications occur in lavas of similar composition; the same distinction holds for nepheline varieties. Leucite is common in lavas but rare in plutonic rocks. Muscovite is confined to intrusions; these differences show the influence of the physical conditions under which consolidation takes place.
Intrusive rocks formed at greater depths are called abyssal. Some intrusive rocks solidified in fissures as dikes and intrusive sills at shallow depth and are called subvolcanic or hypabyssal, they show structures intermediate between those of plutonic rocks. They are commonly porphyritic and sometimes vesicular. In fact, many of them are petrologically indistinguishable from lavas of similar composition. Ellicott City Granodiorite Guilford Quartz Monzonite Methods of pluton emplacement Norbeck Intrusive Suite Volcanic rock Woodstock Quartz Monzonite
Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava; the magma can be crust. The melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. Igneous rocks occur in a wide range of geological settings: shields, orogens, large igneous provinces, extended crust and oceanic crust. Igneous and metamorphic rocks make up 90–95% of the top 16 km of the Earth's crust by volume. Igneous rocks form about 15% of the Earth's current land surface. Most of the Earth's oceanic crust is made of igneous rock. Igneous rocks are geologically important because: their minerals and global chemistry give information about the composition of the mantle, from which some igneous rocks are extracted, the temperature and pressure conditions that allowed this extraction, and/or of other pre-existing rock that melted.
In terms of modes of occurrence, igneous rocks can be either extrusive. Intrusive igneous rocks make up the majority of igneous rocks and are formed from magma that cools and solidifies within the crust of a planet, surrounded by pre-existing rock; the mineral grains in such rocks can be identified with the naked eye. Intrusive rocks can be classified according to the shape and size of the intrusive body and its relation to the other formations into which it intrudes. Typical intrusive formations are batholiths, laccoliths and dikes; when the magma solidifies within the earth's crust, it cools forming coarse textured rocks, such as granite, gabbro, or diorite. The central cores of major mountain ranges consist of intrusive igneous rocks granite; when exposed by erosion, these cores may occupy huge areas of the Earth's surface. Intrusive igneous rocks that form at depth within the crust are termed plutonic rocks and are coarse-grained. Intrusive igneous rocks that form near the surface are termed subvolcanic or hypabyssal rocks and they are medium-grained.
Hypabyssal rocks are less common than plutonic or volcanic rocks and form dikes, laccoliths, lopoliths, or phacoliths. Extrusive igneous rocks known as volcanic rocks, are formed at the crust's surface as a result of the partial melting of rocks within the mantle and crust. Extrusive solidify quicker than intrusive igneous rocks, they are formed by the cooling of molten magma on the earth's surface. The magma, brought to the surface through fissures or volcanic eruptions, solidifies at a faster rate. Hence such rocks are smooth and fine-grained. Basalt is lava plateaus; some kinds of basalt solidify to form long polygonal columns. The Giant's Causeway in Antrim, Northern Ireland is an example; the molten rock, with or without suspended crystals and gas bubbles, is called magma. It rises; when magma reaches the surface from beneath water or air, it is called lava. Eruptions of volcanoes into air are termed subaerial, whereas those occurring underneath the ocean are termed submarine. Black smokers and mid-ocean ridge basalt are examples of submarine volcanic activity.
The volume of extrusive rock erupted annually by volcanoes varies with plate tectonic setting. Extrusive rock is produced in the following proportions: divergent boundary: 73% convergent boundary: 15% hotspot: 12%. Magma that erupts from a volcano behaves according to its viscosity, determined by temperature, crystal content and the amount of silica. High-temperature magma, most of, basaltic in composition, behaves in a manner similar to thick oil and, as it cools, treacle. Long, thin basalt flows with pahoehoe surfaces are common. Intermediate composition magma, such as andesite, tends to form cinder cones of intermingled ash and lava, may have a viscosity similar to thick, cold molasses or rubber when erupted. Felsic magma, such as rhyolite, is erupted at low temperature and is up to 10,000 times as viscous as basalt. Volcanoes with rhyolitic magma erupt explosively, rhyolitic lava flows are of limited extent and have steep margins, because the magma is so viscous. Felsic and intermediate magmas that erupt do so violently, with explosions driven by the release of dissolved gases—typically water vapour, but carbon dioxide.
Explosively erupted pyroclastic material is called tephra and includes tuff and ignimbrite. Fine volcanic ash is erupted and forms ash tuff deposits, which ca
Plagioclase is a series of tectosilicate minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series; this was first shown by the German mineralogist Johann Friedrich Christian Hessel in 1826. The series ranges from albite to anorthite endmembers, where sodium and calcium atoms can substitute for each other in the mineral's crystal lattice structure. Plagioclase in hand samples is identified by its polysynthetic crystal twinning or'record-groove' effect. Plagioclase is a major constituent mineral in the Earth's crust, is an important diagnostic tool in petrology for identifying the composition and evolution of igneous rocks. Plagioclase is a major constituent of rock in the highlands of the Earth's moon. Analysis of thermal emission spectra from the surface of Mars suggests that plagioclase is the most abundant mineral in the crust of Mars.
The composition of a plagioclase feldspar is denoted by its overall fraction of anorthite or albite, determined by measuring the plagioclase crystal's refractive index in crushed grain mounts, or its extinction angle in thin section under a polarizing microscope. The extinction angle varies with the albite fraction. There are several named plagioclase feldspars that fall between anorthite in the series; the following table shows their compositions in terms of constituent anorthite and albite percentages. Anorthite was named by Gustav Rose in 1823 from the Ancient Greek meaning oblique, referring to its triclinic crystallization. Anorthite is a comparatively rare mineral but occurs in the basic plutonic rocks of some orogenic calc-alkaline suites. Albite is named from the Latin albus, in reference to its unusually pure white color, it is a common and important rock-making mineral associated with the more acid rock types and in pegmatite dikes with rarer minerals like tourmaline and beryl. The intermediate members of the plagioclase group are similar to each other and cannot be distinguished except by their optical properties.
The specific gravity in each member increases 0.02 per 10% increase in anorthite. Bytownite, named after the former name for Ottawa, Canada, is a rare mineral found in more basic rocks. Labradorite is the characteristic feldspar of the more basic rock types such as diorite, andesite, or basalt and is associated with one of the pyroxenes or amphiboles. Labradorite shows an iridescent display of colors due to light refracting within the lamellae of the crystal, it is named after Labrador, where it is a constituent of the intrusive igneous rock anorthosite, composed entirely of plagioclase. A variety of labradorite known as spectrolite is found in Finland. Andesine is a characteristic mineral of rocks such as diorite which contain a moderate amount of silica and related volcanics such as andesite. Oligoclase is common in granite, syenite and gneiss, it is a frequent associate of orthoclase. The name oligoclase is derived from the Greek for little and fracture, in reference to the fact that its cleavage angle differs from 90°.
Sunstone is oligoclase with flakes of hematite. Hypersolvus List of minerals Subsolvus
Sheeted dyke complex
A sheeted dyke complex or sheeted dike complex is a normal component of an ophiolite, a piece of oceanic crust, emplaced within a sequence of continental rocks. In the original formation environment below the sea floor the dykes acted as feeders for the overlying sequence of extrusive rocks pillow lavas forming a layer of the oceanic crust; as each injection of a dyke represents one increment of seafloor spreading, each dyke was intruded into earlier dykes. The dykes are dolerites but plagiogranites form a significant part of the complex. Dike swarm
Trondheim is a city and municipality in Trøndelag county, Norway. It has a population of 193,501, is the third-most populous municipality in Norway, although the fourth largest urban area. Trondheim lies on the south shore of Trondheim Fjord at the mouth of the River Nidelva; the city is dominated by the Norwegian University of Science and Technology, the Foundation for Scientific and Industrial Research, St. Olavs University Hospital and other technology-oriented institutions; the settlement was founded in 997 as a trading post, it served as the capital of Norway during the Viking Age until 1217. From 1152 to 1537, the city was the seat of the Catholic Archdiocese of Nidaros, it was incorporated in 1838. The current municipality dates from 1964, when Trondheim merged with Byneset, Leinstrand and Tiller; the city functions as the seat of the County Mayor of Trøndelag county, but not as the administrative centre, Steinkjer. This is to make the county more efficient and not too centralized, as Trøndelag is the second largest county in Norway.
The city was given the name by Olav Tryggvason. It was for a long time called Niðaróss in the Old Norse spelling, but it was just called kaupangr or, more kaupangr í Þróndheimi. In the late Middle Ages people started to call the city just Þróndheimr. In the Dano-Norwegian period, during the years as a provincial town in the united kingdoms of Denmark–Norway, the city name was spelled Trondhjem. Following the example set by the renaming of the capital Kristiania to Oslo, Nidaros was reintroduced as the official name of the city for a brief period from 1 January 1930 until 6 March 1931; the name was restored in order to reaffirm the city's link with its glorious past, despite the fact that a 1928 referendum on the name of the city had resulted in 17,163 votes in favour of Trondhjem and only 1,508 votes in favour of Nidaros. Public outrage in the same year taking the form of riots, forced the Storting to settle for the medieval city name Trondheim; the name of the diocese was, changed from Trondhjem stift to Nidaros bispedømme in 1918.
Trondheim was named Drontheim during the Second World War, as a German exonym. Trondheimen indicates the area around Trondheim Fjord; the spelling Trondhjem was rejected, but many still prefer that spelling of the city's name. For the ecclesiastical history, see Archiepiscopate of NidarosTrondheim was named Kaupangen by Viking King Olav Tryggvason in 997. Shortly thereafter it came to be called Nidaros. In the beginning it was used as a military retainer of King Olav I, it was used as the seat of the king, was the capital of Norway until 1217. People have been living in the region for thousands of years as evidenced by the rock carvings in central Norway, the Nøstvet and Lihult cultures and the Corded Ware culture. In ancient times, the Kings of Norway were hailed at Øretinget in Trondheim, the place for the assembly of all free men by the mouth of the River Nidelva. Harald Fairhair was hailed as the king here, as was his son, Haakon I, called'the Good'; the battle of Kalvskinnet took place in Trondheim in 1179: King Sverre Sigurdsson and his Birkebeiner warriors were victorious against Erling Skakke.
Some scholars believe that the famous Lewis chessmen, 12th century chess pieces carved from walrus ivory found in the Hebrides and now at the British Museum, may have been made in Trondheim. Trondheim was the seat of the Archbishop of Nidaros for Norway from 1152, who operated from the Archbishop's Palace. Due to the introduction of Lutheran Protestantism in 1537, the last Archbishop, Olav Engelbrektsson, had to flee from the city to the Netherlands, where he died in present-day Lier, Belgium; the city has experienced several major fires. Since much of the city was made of wooden buildings, many of the fires caused severe damage. Great fires ravaged the city in 1598, 1651, 1681, 1708, twice in 1717, 1742, 1788, 1841 and 1842; the 1651 fire destroyed 90% of all buildings within the city limits. The fire in 1681 led to an total reconstruction of the city, overseen by General Johan Caspar von Cicignon from Luxembourg. Broad avenues like Munkegaten were created, with no regard for property rights, in order to stop the next fire.
At the time, the city had a population of 8000 inhabitants. After the Treaty of Roskilde on 26 February 1658, Trondheim and the rest of Trøndelag, became Swedish territory for a brief period, but the area was reconquered 10 months later; the conflict was settled by the Treaty of Copenhagen on 27 May 1660. During the Second World War, Trondheim was occupied by Nazi Germany from 9 April 1940, the first day of the invasion of Norway, until the end of the war in Europe, 8 May 1945; the German invasion force consisted of the German cruiser Admiral Hipper, 4 destroyers and 1700 Austrian Mountain troops. Other than a coastal battery opening fire, there was no resistance to the invasion on 9 April at 5 AM. On 14 and 17 April and French forces landed near Trondheim in a failed attempt to liberate Trondheim as part of the Namsos Campaign. During the occupation, Trondheim was the home of the notorious Norwegian Gestapo agent, Henry Rinnan, who operated from a nearby villa a