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23-535: From the Transylvanian Plateau , with heights between 200 and 400 metres (660 and 1,310 ft), in the North and East, the heights grow abruptly through a zone of deep valleys at about 900 m (3,000 ft) on the verge of the massif where some villages are situated. The heights continue to grow slowly towards the highest peak, Cindrel Peak , at 2,244 m (7,362 ft). Only two other peaks in

46-577: A salt dome . 46°30′N 24°30′E  /  46.500°N 24.500°E  / 46.500; 24.500 Salt dome A salt dome is a type of structural dome formed when salt (or other evaporite minerals) intrudes into overlying rocks in a process known as diapirism . Salt domes can have unique surface and subsurface structures, and they can be discovered using techniques such as seismic reflection . They are important in petroleum geology as they can function as petroleum traps . Stratigraphically, salt basins developed periodically from

69-430: A height of 150–250 m (490–820 ft) above the altitude of the valley. The plateau has a continental climate . Temperature varies a great deal in the course of a year, with warm summers contrasted by very cold winters. Vast forests cover parts of the plateau and the mountains. The mean elevation is 300–500 m (980–1,640 ft). The Transylvanian Plateau is divided into three areas: The Transylvanian Plain

92-716: Is a plateau in central Romania . The plateau lies within and takes its name from the historical region of Transylvania , and is almost entirely surrounded by the Eastern , Southern and Romanian Western branches of the Carpathian Mountains . The area includes the Transylvanian Plain . It is improperly called a plateau, for it does not possess extensive plains, but is formed of a network of valleys of various size, ravines and canyons , united together by numerous small mountain ranges , which attain

115-553: Is also hilly (400–600 m), but because the area is almost completely cultivated it is called a plain. The Transylvanian Basin ( Romanian : Depresiunea colinară a Transilvaniei ) includes the Transylvanian Plateau and the peripheral areas towards the Carpathian Mountains, which have a different character than the plateau. The basin is the main production site of Romania's methane . It also contains

138-599: Is home to most of the US Strategic Petroleum Reserve . Avery Island was formed by a salt dome. During the break-up of the south Atlantic, Aptian (Lower Cretaceous) age salt was deposited within the area of thinned crust on both the Brazilian and conjugate Angola/Gabon margins forming many salt domes. During the Messinian salinity crisis ( Late Miocene ), thick salt layers were formed as

161-439: Is recognized that a single evaporation event is rarely enough to produce the vast quantities of salt needed to form a layer thick enough for the formation of salt diapirs , indicating that a sustained period of episodic flooding and evaporation of the basin must occur. Over time, the layer of salt is covered with deposited sediment , becoming buried under an increasingly large overburden . Previously, researchers believed that

184-587: The Paradox Formation forms salt domes throughout the Paradox Basin in the US, which extends from eastern Utah , through southwestern Colorado into northwestern New Mexico . An example of an emergent salt dome is at Onion Creek, Utah / Fisher Towers near Moab, Utah. A Paradox Formation salt body that has risen as a ridge through several hundred meters of overburden, predominantly sandstone . As

207-520: The Proterozoic to the Neogene . The formation of a salt dome begins with the deposition of salt in a restricted basin . In these basins, the outflow of water exceeds inflow. Specifically, the basin loses water through evaporation , resulting in the precipitation and deposition of salt. While the rate of sedimentation of salt is significantly larger than the rate of sedimentation of clastics , it

230-560: The United States. Several countries use solution mining to form caverns for holding large amounts of oil or gas reserves . The caprock above the salt domes can contain deposits of native sulfur (recovered by the Frasch process ). They can also contain deposits of metals, sodium salts , nitrates , and other substances, which can be used in products such as table salt and chemical de-icers . Salt domes occur in many parts of

253-402: The accumulation of sediments around the diapir contribute to its growth and eventually form into a dome. Some salt domes can be seen from Earth's surface. They can also be located by finding unique surface structures and surrounding phenomena. For instance, salt domes can contain or be near sulfur springs and natural gas vents . Some salt domes have salt sheets that extrude from the top of

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276-529: The central and southern North Sea , extending eastwards into Germany. Upper Triassic salt forms salt domes in the Essaouira Basin onshore and offshore Morocco. An equivalent salt sequence, the Argo Formation, is associated with salt dome formation on the conjugate Nova Scotia margin . The Gulf Coast is home to over 500 salt domes formed from Middle Jurassic Louann Salt . This region

299-509: The compaction of overlying sediment and subsequent decrease in buoyancy led to salt rising and intruding into the overburden due to its ductility , thereby creating a salt diapir. However, after the 1980s, the primary force that drives the flow of salt is considered to be differential loading. Differential loading can be caused by gravitational forces ( gravitational loading ), forced displacement of salt boundaries ( displacement loading ), or thermal gradients ( thermal loading ). The flow of

322-409: The dome, forming pockets and reservoirs of petroleum and natural gas (known as petroleum traps) . In 1901, an exploratory oil well was drilled into Spindletop Hill near Beaumont , Texas. This led to the discovery of the first salt dome, revealed the importance of salt to the formation of hydrocarbon accumulations, and produced enough oil for petroleum to become an economically feasible fuel for

345-508: The dome; these are referred to as salt plugs. These plugs can coalesce to form salt canopies, which can then be remobilized by roof sedimentation, with the most prominent example in the northern Gulf of Mexico basin . Another structure that can form from salt domes are salt welds . These occur when the growth of a dome is prevented by an exhausted supply of salt, and the top and bottom contacts merge. Salt domes have also been located using seismic refraction and seismic reflection . The latter

368-437: The expansion of offshore petroleum exploration efforts led to the discovery of numerous salt domes soon after World War II . Salt domes are the site of many of the world's hydrocarbon provinces. The rock salt of the salt dome is mostly impermeable, so, as it moves up towards the surface, it penetrates and bends existing rock along with it. As strata of rock are penetrated, they are, generally, bent upwards where they meet

391-831: The last part of his life. The main river flowing from the mountain is the Cibin River, which collects most of the other smaller rivers. Between the Cindrel Mountains and the Transylvanian Plateau, the river forms a wide depression—the Sibiu Depression  [ ro ] —in which the main city in the area, Sibiu , lies. The ethnographic region known as Mărginimea Sibiului is located there. 45°35′N 23°47′E  /  45.583°N 23.783°E  / 45.583; 23.783 Transylvanian Plateau The Transylvanian Plateau ( Romanian : Podișul Transilvaniei ; Hungarian : Erdélyi-medence )

414-699: The main occupations. On the Cibin and the Sadu rivers dams and hydro-electrical power plants were constructed, the oldest being the one from Sadu in 1896. The Păltiniș resort is situated halfway between the village of Rășinari and the Cindrel Peak  [ ro ] , with hotels, chalets and a ski slope. The resort has developed around a small monastery in which the Romanian philosopher Constantin Noica spent

437-475: The range rise above 2000 metres: Balandrul Mare (2,210 m (7,250 ft)) and Starpului (2,146 m (7,041 ft)). Mount Cindrel was the site of the World War I Battle of Mount Csindrel , part of the 1916 Battle of Transylvania . Because the massif is easily accessible, the ethnographical area Mărginimea Sibiului has formed around the mountain, having sheep-herding and wood industry as

460-553: The salt body rose, the overburden formed an anticline (arching upward along its center line) which fractured and eroded to expose the salt body. Offshore northern Norway in the southwestern Barents Sea , thick Upper Carboniferous – Lower Permian salt was deposited, forming salt domes in the Hammerfest and Nordkapp basins. In northwest Europe Upper Permian salt of the Zechstein Group has formed salt domes over

483-425: The salt overcomes the strength of the overburden as well as boundary friction aided by overburden extension , erosion, thrust faults , ductile thinning, or other forms of regional deformation. The vertical growth of salt formations creates pressure on the upward surface, causing extension and faulting . Once the salt completely pierces the overburden, it can rise through a process known as passive diapirism where

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506-860: The world where there is a sufficiently thick layer of rock salt developed. In the Middle East, the upper Neoproterozoic salt of the Hormuz Formation is associated with widespread salt dome formation in most parts of the Persian Gulf and onshore in Iran, Iraq, United Arab Emirates , and Oman . The thicker salt is found in a series of basins: the Western Gulf, the Southern Gulf, and the Oman salt basins. Pennsylvanian age salt of

529-512: Was developed based on techniques from the former and is more effective. Seismic refraction uses seismic waves to characterize subsurface geologic conditions and structures. Seismic reflection highlights the presence of a stark density contrast between the salt and surrounding sediment. Seismic techniques are particularly effective as salt domes are typically depressed blocks of crust bordered by parallel normal faults ( graben ) that can be flanked by reverse faults. Advances in seismic reflection and

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