Orogeny is a mountain building process that takes place at a convergent plate margin when plate motion compresses the margin. An orogenic belt or orogen develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involves a series of geological processes collectively called orogenesis. These include both structural deformation of existing continental crust and the creation of new continental crust through volcanism. Magma rising in the orogen carries less dense material upwards while leaving more dense material behind, resulting in compositional differentiation of Earth's lithosphere. A synorogenic process or event is one that occurs during an orogeny.
Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically 50 to 100 kilometers wide and 3 to 4 km below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about 50,000 km (31,000 mi) of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of 10,920 m (35,830 ft) below sea level.
Forearc is a plate tectonic term referring to a region between an oceanic trench, also known as a subduction zone, and the associated volcanic arc. Forearc regions are present along a convergent margins and eponymously form 'in front of' the volcanic arcs that are characteristic of convergent plate margins. A back-arc region is the companion region behind the volcanic arc.
The Messinian salinity crisis (MSC), also referred to as the Messinian event, and in its latest stage as the Lago Mare event, was a geological event during which the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (drying-up) throughout the latter part of the Messinian age of the Miocene epoch, from 5.96 to 5.33 Ma. It ended with the Zanclean flood, when the Atlantic reclaimed the basin.
A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithosphere to bend, by a process known as lithospheric flexure. The width and depth of the foreland basin is determined by the flexural rigidity of the underlying lithosphere, and the characteristics of the mountain belt. The foreland basin receives sediment that is eroded off the adjacent mountain belt, filling with thick sedimentary successions that thin away from the mountain belt. Foreland basins represent an endmember basin type, the other being rift basins. Space for sediments is provided by loading and downflexure to form foreland basins, in contrast to rift basins, where accommodation space is generated by lithospheric extension.
The geology of the Iberian Peninsula consists of the study of the rock formations on the Iberian Peninsula, which includes Spain, Portugal, Andorra, and Gibraltar. The peninsula contains rocks from every geological period from the Ediacaran to the Quaternary, and many types of rock are represented. World-class mineral deposits are also found there.
An accretionary wedge or accretionary prism forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust, but in some cases the wedge includes the erosional products of volcanic island arcs formed on the overriding plate.
The Gibraltar Arc is a geological region corresponding to an arcuate orogen surrounding the Alboran Sea, between the Iberian Peninsula and Africa. It consists of the Betic Cordillera, and the Rif. The Gibraltar Arc is located at the western end of the Mediterranean Alpine belt and formed during the Neogene due to convergence of the Eurasian and African plates.
The Owen Fracture Zone (OFZ), though misnamed a fracture zone, is a transform fault in the northwest Indian Ocean that separates the Arabian and African Plates from the Indian Plate. Extending north-northeast from where the Carlsberg Ridge meets the Sheba ridge in the south to the Makran Subduction Zone in the north, it represents the port side of the northward motion of the Indian subcontinent during the Late Cretaceous–Palaeogene break-up of Gondwana. Slip along the Owen Fracture Zone is occurring at 2 mm (0.079 in)/yr, the slowest rate on Earth, which means the Arabian Plate moves northward faster than the Indian Plate.
The Sorbas Basin is a sedimentary basin around the town of Sorbas in Almeria Province in south-east Spain. It is believed to have been formed by extension, between two fault-bounded blocks which rotated anti-clockwise to take up the compression resulting from Europe's collision with Africa. The basin is filled with turbidites and evaporites of the Tortonian-Messinian ages of the Miocene Epoch.
The Messinian Erosional Crisis is a phase in the Messinian evolution of the central Mediterranean basin resulting from major drawdown of the Mediterranean seawater.
L'Atalante basin is a hypersaline brine lake at the bottom of the Mediterranean Sea about 192 km (119 mi) west of the island of Crete. It is named for the French L'Atalante, one of the oceanographic research vessels involved in its discovery in 1993. L'Atalante and its neighbors the Urania and Discovery deep hyper saline anoxic basins (DHABs) are at most 35,000 years old. They were formed by Messinian evaporite salt deposits dissolving out of the Mediterranean Ridge and collecting in abyssal depressions about 3,000 m (9,800 ft) deep. L'Atalante is the smallest of the three; its surface begins at about 3,500 m (11,500 ft) below sea level.
The Hellenic Trench (HT) is an oceanic trough located in the forearc of the Hellenic Arc, an arcuate archipelago on the southern margin of the Aegean Sea Plate, or Aegean Plate, also called Aegea, the basement of the Aegean Sea. The HT begins in the Ionian Sea near the mouth of the Gulf of Corinth and curves to the south, following the margin of the Aegean Sea. It passes close to the south shore of Crete and ends near the island of Rhodes just offshore Anatolia.
Tectonic subsidence is the sinking of the Earth's crust on a large scale, relative to crustal-scale features or the geoid. The movement of crustal plates and accommodation spaces created by faulting create subsidence on a large scale in a variety of environments, including passive margins, aulacogens, fore-arc basins, foreland basins, intercontinental basins and pull-apart basins. Three mechanisms are common in the tectonic environments in which subsidence occurs: extension, cooling and loading.
Salt surface structures are extensions of salt tectonics that form at the Earth's surface when either diapirs or salt sheets pierce through the overlying strata. They can occur in any location where there are salt deposits, namely in cratonic basins, synrift basins, passive margins and collisional margins. These are environments where mass quantities of water collect and then evaporate; leaving behind salt and other evaporites to form sedimentary beds. When there is a difference in pressure, such as additional sediment in a particular area, the salt beds – due to the unique ability of salt to behave as a fluid under pressure – form into new structures. Sometimes, these new bodies form subhorizontal or moderately dipping structures over a younger stratigraphic unit, which are called allochthonous salt bodies or salt surface structures.
The geology of Myanmar is shaped by dramatic, ongoing tectonic processes controlled by shifting tectonic components as the Indian plate slides northwards and towards Southeast Asia. Myanmar spans across parts of three tectonic plates separated by north-trending faults. To the west, a highly oblique subduction zone separates the offshore Indian plate from the Burma microplate, which underlies most of the country. In the center-east of Myanmar, a right lateral strike slip fault extends from south to north across more than 1,000 km (620 mi). These tectonic zones are responsible for large earthquakes in the region. The India-Eurasia plate collision which initiated in the Eocene provides the last geological pieces of Myanmar, and thus Myanmar preserves a more extensive Cenozoic geological record as compared to records of the Mesozoic and Paleozoic eras. Myanmar is physiographically divided into three regions: the Indo-Burman Range, Myanmar Central Belt and the Shan Plateau; these all display an arcuate shape bulging westwards. The varying regional tectonic settings of Myanmar not only give rise to disparate regional features, but they also foster the formation of petroleum basins and a diverse mix of mineral resources.
The geology of Sicily records the collision of the Eurasian and the African plates during westward-dipping subduction of the African slab since late Oligocene. Major tectonic units are the Hyblean foreland, the Gela foredeep, the Apenninic-Maghrebian orogen, and the Calabrian Arc. The orogen represents a fold-thrust belt that folds Mesozoic carbonates, while a major volcanic unit is found in an eastern portion of the island. The collision of Africa and Eurasia is a retreating subduction system, such that the descending Africa is falling away from Eurasia, and Eurasia extends and fills the space as the African plate falls into the mantle, resulting in volcanic activity in Sicily and the formation of Tyrrhenian slab to the north.
The Zanclean flood or Zanclean deluge is a flood theorized to have refilled the Mediterranean Sea 5.33 million years ago. This flooding ended the Messinian salinity crisis and reconnected the Mediterranean Sea to the Atlantic Ocean, although it is possible that even before the flood there were partial connections to the Atlantic Ocean. The reconnection marks the beginning of the Zanclean age.
The Hellenic subduction zone (HSZ) is the convergent boundary between the African Plate and the Aegean Sea Plate, where oceanic crust of the African is being subducted north–northeastwards beneath the Aegean. The southernmost and shallowest part of the zone is obscured beneath the deformed thick sedimentary sequence that forms the Mediterranean Ridge accretionary complex. It has a well-defined Wadati–Benioff zone of seismicity, which demonstrates the relatively shallow dip of its southern part, which increases markedly to the north of the non-volcanic part of the Hellenic arc. The descending slab has been imaged using seismic tomography down to the top of the mantle transition zone at 410 km depth.
The Laga Basin is the largest and youngest foreland basin of the Central Apennines fold and thrust belt. It is Messinian in age and serves as a link between an Early Miocene aged fold and thrust belt at the west of the Central Apennines and a younger belt to the east. In the 1980s and 1990s, it was the subject of numerous investigations for hydrocarbon resources, and since has become a valuable analogue with relation to clastic reservoirs developed in confined structural settings.
