The Makran Trench is the physiographic expression of a subduction zone along the northeastern margin of the Gulf of Oman adjacent to the southwestern coast of

Balochistan Balochistan ( ; bal, بلۏچستان; also romanised as Baluchistan and Baluchestan) is a historical region in Western and South Asia, located in the Iranian plateau's far southeast and bordering the Indian Plate and the Arabian Sea coastline. ...

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...

and the southeastern coast of

Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...

. In this region the

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic ...

of the

Arabian Plate The Arabian Plate is a minor tectonic plate in the Northern and Eastern Hemispheres. It is one of the three continental plates (along with the African and the Indian Plates) that have been moving northward in geological history and colliding ...

is being subducted beneath the

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called '' sial'' be ...

of the

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

Tectonics

In the Makran region, the Arabian Plate subducts beneath the Eurasian Plate at ~2-4cm/yr. This subduction is associated with an

accretionary wedge 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 d ...

of sediments which has developed since the

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

. To the west, the Makran Trench is connected by the Minab Fault system to the

Zagros fold and thrust belt The Zagros fold and thrust belt (Zagros FTB) is an approximately long zone of deformed crustal rocks, formed in the foreland of the collision between the Arabian Plate and the Eurasian Plate. It is host to one of the world's largest petroleum pr ...

. To the east, the Makran Trench is bounded by the

transpression In geology, transpression is a type of strike-slip deformation that deviates from simple shear because of a simultaneous component of shortening perpendicular to the fault plane. This movement ends up resulting in oblique shear. It is generally v ...

al strike-slip Ornach-Nal and Chaman Faults, which connect to the

Himalaya The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 100 ...

n orogeny. The Makran Subduction Zone is often split into two segments: the east and west. The Sonne fault divides the two. Though largely much quieter than many other subduction zones, studies reveal that the Makran Trench may be capable of very large earthquakes, even extending into the magnitude 9 range.

Fluids, gas and mud volcanoes

The Makran accretionary complex is characterized by a number of features associated with escaping water and

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...

Mud volcano A mud volcano or mud dome is a landform created by the eruption of mud or slurries, water and gases. Several geological processes may cause the formation of mud volcanoes. Mud volcanoes are not true igneous volcanoes as they do not produce la ...

es are found onshore in both Iran and Pakistan, and

cold seeps A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. ''Cold'' does not mean that the temperature of the see ...

exist offshore. The formation of an island (

Zalzala Jazeera Zalzala Koh (, ''Earthquake Mountain'') or Zalzala Jazeera (''Earthquake Island'') was a small island off the coast of the port city of Gwadar in Balochistan province of Pakistan which appeared on 24 September 2013 following an earthquake. As pre ...

) after the 2013 Balochistan earthquakes is thought to be the result of a mud volcano. An island (Malan island) formed as a mud volcano subsided under water due to gas release and mud extrusion. Heavy rain from monsoon season built pressure to the aquifer, enhancing the release of gas.

Earthquakes

* 1945 Balochistan earthquake: A

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

8.1 event occurred on 28 November, causing a

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...

on the Makran coast. * 5 August 1947: Mw 6.8 event just off the coast of western Pakistan * 7 December 1989: Mw 6.0 event near the coast of southern Iran * 7 February 2017: Mw 6.3 event just off the coast of western Pakistan

References

Geology of Iran Geology of Pakistan Subduction zones {{tectonics-stub

Tectonics

Fluids, gas and mud volcanoes

Earthquakes

See also

References