Bohuslän (Swedish pronunciation:[ˈbûːhʉːsˌlɛːn] is a Swedish province in Götaland, on the northernmost part of the country's west coast. It is bordered by Dalsland to the northeast, Västergötland to the southeast, the Skagerrak arm of the North Sea to the west, and the county of Østfold, in Norway, to the north. In English it literally means Bohus County, although it shared counties with the city of Gothenburg prior to the 1998 county merger and thus was not an administrative unit in its own right.
The Congo Craton, covered by the Palaeozoic-to-recent Congo Basin, is an ancient Precambrian craton that with four others makes up the modern continent of Africa. These cratons were formed between about 3.6 and 2.0 billion years ago and have been tectonically stable since that time. All of these cratons are bounded by younger fold belts formed between 2.0 billion and 300 million years ago.
The Oslo Graben or Oslo Rift is a graben formed during a geologic rifting event in Permian time, the last phase of the Variscan orogeny. The main graben forming period began in the late Carboniferous, which culminated with rift formation and volcanism, with associated rhomb porphyry lava flows. This activity was followed by uplifting, and ended with intrusions about 65 million years after the onset of the formation. It is located in the area around the Norwegian capital Oslo.
The Fen Complex in Nome, Telemark, Norway is a region noted for an unusual suite of igneous rocks. Several varieties of carbonatite are present in the area as well as lamprophyre, ijolite and other highly alkalic rocks. It is the type locality for fenite, a metasomatic rock commonly found around carbonatite and alkali intrusives.
The Amazonian Craton is a geologic province located in South America. It occupies a large portion of the central, north and eastern part of the continent and represents one of Earth's largest cratonic regions. The Guiana Shield and Central Brazil Shield constitute respectively the northern and southern exhumed parts of the craton. Between the two shields lies the Amazon Rift, a zone of weakness within the craton. Smaller cratons of Precambrian rocks south of the Amazonian Shield are the Río de la Plata Craton and the São Francisco Craton, which lies to the east.
The geology of Norway encompasses the history of Earth that can be interpreted by rock types found in Norway, and the associated sedimentological history of soils and rock types.
A dike swarm or dyke swarm is a large geological structure consisting of a major group of parallel, linear, or radially oriented magmatic dikes intruded within continental crust or central volcanoes in rift zones. Examples exist in Iceland and near other large volcanoes, around the world. They consist of several to hundreds of dikes emplaced more or less contemporaneously during a single intrusive event, are magmatic and stratigraphic, and may form a large igneous province.
The Grenville dike swarm is a large Proterozoic dike swarm in the Canadian provinces of Ontario and Quebec. It is one of the several major magmatic events in the Canadian Shield and it possibly formed 590 million years ago along a triple junction that might have been related to a mantle plume. The maximum length of the Grenville dike swarm is 700 km (435 mi).
The Lewisian complex or Lewisian gneiss is a suite of Precambrian metamorphic rocks that outcrop in the northwestern part of Scotland, forming part of the Hebridean Terrane and the North Atlantic Craton. These rocks are of Archaean and Paleoproterozoic age, ranging from 3.0–1.7 billion years (Ga). They form the basement on which the Stoer Group, Wester Ross Supergroup and probably the Loch Ness Supergroup sediments were deposited. The Lewisian consists mainly of granitic gneisses with a minor amount of supracrustal rocks. Rocks of the Lewisian complex were caught up in the Caledonian orogeny, appearing in the hanging walls of many of the thrust faults formed during the late stages of this tectonic event.
The Sveconorwegian orogeny was an orogenic system active 1140 to 960 million years ago and currently exposed as the Sveconorwegian orogenic belt in southwestern Sweden and southern Norway. In Norway the orogenic belt is exposed southeast of the front of the Caledonian nappe system and in nappe windows. The Sveconorwegian orogen is commonly grouped within the Grenvillian Mesoproterozoic orogens. Contrary to many other known orogenic belts the Sveconorwegian orogens eastern border does not have any known suture zone with ophiolites.
The Transscandinavian Igneous Belt, abbreviated TIB, is one of the major lithological units of the Baltic Shield. It consists of a series of batholiths in Sweden and Norway forming a ca. 1400 km long belt running from Lofoten, Norway, in the north to Blekinge, Sweden, in the south. The Transscandinavian Igneous Belt and its rocks solidified from magma between 1810 and 1650 million years ago during the Mesoproterozoic. The Transscandinavian Igneous Belt was likely formed in an Andean-type geological environment, implying it was once parallel to a destructive plate boundary. The belt was first identified in the 1980s and was referred as the "Transscandinavian Granite-Porphyry Belt". The current name was first applied in 1987.
The Svecofennian orogeny is a series of related orogenies that resulted in the formation of much of the continental crust in what is today Sweden and Finland plus some minor parts of Russia. The orogenies lasted from about 2000 to 1800 million years ago during the Paleoproterozoic Era. The resulting orogen is known as the Svecofennian orogen or Svecofennides. To the west and southwest the Svecofennian orogen limits with the generally younger Transscandinavian Igneous Belt. It is assumed that the westernmost fringes of the Svecofennian orogen have been reworked by the Sveconorwegian orogeny just as the western parts of the Transscandinavian Igneous Belt has. The Svecofennian orogeny involved the accretion of numerous island arcs in such manner that the pre-existing craton grew with this new material from what is today northeast to the southwest. The accretion of the island arcs was also related to two other processes that occurred in the same period; the formation of magma that then cooled to form igneous rocks and the metamorphism of rocks.
The Gothian orogeny or Kongsberg orogeny was an orogeny in western Fennoscandia that occurred between 1750 and 1500 million years ago. It precedes the younger Sveconorwegian orogeny that has overprinted much of it. The Gothian orogeny formed along a subduction zone and resulted in the formation of calc-alkaline igneous rocks 1700 to 1550 million years ago, including some of the younger members of the Transscandinavian Igneous Belt.
The Satakunta dyke swarms are a series of dyke swarms, a group of magmatic intrusions, of Mesoproterozoic age in the Bothnian Sea and western and central Finland. They are made up of Subjotnian diabase dikes, associated with rapakivi magmatism. They were most likely formed on the Columbia supercontinent.
The dyke swarms of Tandil and Azul are groups of dykes of Proterozoic age located in Buenos Aires Province, Argentina. The dyke swarms consist of two groups: 2000 million year old dykes of calc-alkaline type and 1600 million year old dykes of tholeiitic type.
The Protogine Zone is a geological boundary zone in western Sweden. There are two slightly different definitions of the Protogine Zone. In the lithological definition it forms the limit between the gneisses of western Sweden and the relatively underformed eastern granites. As such it makes up the limit of deformation and metamorphism attributed to the Sveconorwegian orogeny. In the tectonic definition it is a zone of strong deformation that follows roughly the same course as the lithological Protogine Zone. In the two definitions of the Protogine Zone it runs from Scania across Lake Vättern into the upper course of Klarälven and then into Norway. The tectonic Protogine Zone has anastomosing branches and splits south of Lake Vättern into various diverging arms. The two westernmost of these arms follow the valleys of the Nissan and Lagan rivers. A more eastern branch is reflected in the alignment of the lakes Rusken, Rymmen and Möckeln.
The Bohus granite is a type of granite that crops out along the Swedish West Coast in Bohuslän. In Norway the same granites are termed Iddefjord granite, Østfold granite and Halden granite. A large quarrying industry has developed around the granites, mainly producing blocks. Large scale extraction begun in the 1840s and employment in the quarries peaked in the 1920s with over 7,000 people working in the industry. The rock is valued for its durability. In the first half of the 20th century the transport of quarried Bohus granite was done with the aid of by the Lysekil Line. In Norway Iddefjord granite has been a relatively common rock in architecture, and many of the statues of Frogner Park in Oslo are made of Iddefjord granite. Iddefjord granite is the official county rock of Østfold in Norway.
The Western Gneiss Region is a large geological unit in Norway chiefly made of gneiss rock that formed through metamorphism during the Caledonian orogeny. It makes up a tectono-stratigraphic terrane of the Scandinavian Caledonides and is also part of the Baltic shield. The region extends across western Norway from Bergen to Trondheim as a Caledonian window, outliers of the Western Gneiss Region crop out as far north as the Lofoten archipelago. The rocks of the Western Gneiss Region are made up of variously deformed Precambrian basement, and cover rocks of autochthonous and para-autochthonous origin with evidence of medium to high grade metamorphism including ultra-high-pressure metamorphism.
The Scandinavian Caledonides are the vestiges of an ancient, today deeply eroded orogenic belt formed during the Silurian–Devonian continental collision of Baltica and Laurentia, which is referred to as the Scandian phase of the Caledonian orogeny. The size of the Scandinavian Caledonides at the time of their formation can be compared with the size of the Himalayas. The area east of the Scandinavian Caledonides, including parts of Finland, developed into a foreland basin where old rocks and surfaces were covered by sediments. Today, the Scandinavian Caledonides underlay most of the western and northern Scandinavian Peninsula, whereas other parts of the Caledonides can be traced into West and Central Europe as well as parts of Greenland and eastern North America.
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.
