The geology of Turkey is the product of a wide variety of tectonic processes that have shaped

Anatolia Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...

over millions of years, a process which continues today as evidenced by frequent earthquakes and occasional

volcanic eruption Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are oft ...

Background

Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolian Peninsula in Western Asia, with a small portion on the Balkan Peninsula ...

's terrain is structurally complex. A central massif composed of uplifted blocks and downfolded troughs, covered by recent deposits and giving the appearance of a plateau with rough terrain, is wedged between two folded mountain ranges that converge in the east. True lowland is confined to the plain of the

Ergene Ergene ( tr, Ergene Nehri; grc, Εργίνης, ''Eryinis'') is a major left tributary of the Maritsa (Meriç) river, flowing entirely in the East Thrace region of Turkey. The river rises from the southern part of Strandzha mountain, not far fro ...

river in

Thrace Thrace (; el, Θράκη, Thráki; bg, Тракия, Trakiya; tr, Trakya) or Thrake is a geographical and historical region in Southeast Europe, now split among Bulgaria, Greece, and Turkey, which is bounded by the Balkan Mountains to ...

, extending along rivers that discharge into the

Aegean Sea The Aegean Sea ; tr, Ege Denizi ( Greek: Αιγαίο Πέλαγος: "Egéo Pélagos", Turkish: "Ege Denizi" or "Adalar Denizi") is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans ...

or the

Sea of Marmara The Sea of Marmara,; grc, Προποντίς, Προποντίδα, Propontís, Propontída also known as the Marmara Sea, is an inland sea located entirely within the borders of Turkey. It connects the Black Sea to the Aegean Sea via t ...

, and to a few narrow coastal strips along the

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Rom ...

and

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...

coasts. Nearly 85% of the land is at an elevation of at least 450 meters; the median altitude of the country is 1,128 meters. In Asiatic Turkey, flat or gently sloping land is rare and largely confined to the deltas of the Kızıl River, the coastal plains of

Antalya la, Attalensis grc, Ἀτταλειώτης , postal_code_type = Postal code , postal_code = 07xxx , area_code = (+90) 242 , registration_plate = 07 , blank_name = Licence plate ...

and

Adana Adana (; ; ) is a major city in southern Turkey. It is situated on the Seyhan River, inland from the Mediterranean Sea. The administrative seat of Adana province, it has a population of 2.26 million. Adana lies in the heart of Cilicia, wh ...

, and the valley floors of the

Gediz River The Gediz River ( tr, Gediz Nehri, ) is the second-longest river in Anatolia flowing into the Aegean Sea. From its source of Mount Murat in Kütahya Province, it flows generally west for to the Gediz River Delta in the Gulf of İzmir. Name T ...

and the

Büyük Menderes River The Büyük Menderes River (historically the Maeander or Meander, from Ancient Greek: Μαίανδρος, ''Maíandros''; tr, Büyük Menderes Irmağı), is a river in southwestern Turkey. It rises in west central Turkey near Dinar before fl ...

, and some interior high plains in Anatolia, mainly around Tuz Gölü (Salt Lake) and Konya Ovası (Konya Basin). Moderately sloping terrain is limited almost entirely outside Thrace to the hills of the Arabian Platform along the border with Syria. More than 80% of the land surface is rough, broken, and mountainous, and therefore is of limited agricultural value. The terrain's ruggedness is accentuated in the eastern part of the country, where the two mountain ranges converge into a lofty region with a median elevation of more than 1,500 meters, which reaches its highest point along the borders with

Armenia Armenia (), , group=pron officially the Republic of Armenia,, is a landlocked country in the Armenian Highlands of Western Asia.The UNbr>classification of world regions places Armenia in Western Asia; the CIA World Factbook , , and ''O ...

Azerbaijan Azerbaijan (, ; az, Azərbaycan ), officially the Republic of Azerbaijan, , also sometimes officially called the Azerbaijan Republic is a transcontinental country located at the boundary of Eastern Europe and Western Asia. It is a part of th ...

, and

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 ...

. Turkey's highest peak,

Mount Ararat Mount Ararat or , ''Ararat''; or is a snow-capped and dormant compound volcano in the extreme east of Turkey. It consists of two major volcanic cones: Greater Ararat and Little Ararat. Greater Ararat is the highest peak in Turkey and th ...

(Ağrı Dağı)—about 5,166 meters high—is situated near the point where the boundaries of the four countries meet.

Geological history

The earliest geological history of Turkey is poorly understood, partly because these oldest rocks in the region are involved into younger deformation phases that hindered their evolution. This created problem of reconstructing how the region has been tectonically assembled by plate motions. Turkey can be thought of as a collage of different continental pieces and remnants of oceanic lithospheric rocks amalgamated together by younger tectonic processes that involve accumulation of igneous (both plutonic and volcanic) and sedimentary rocks.

Plate tectonics

Except for a relatively small portion of its territory along the

Syria Syria ( ar, سُورِيَا or سُورِيَة, translit=Sūriyā), officially the Syrian Arab Republic ( ar, الجمهورية العربية السورية, al-Jumhūrīyah al-ʻArabīyah as-Sūrīyah), is a Western Asian country loc ...

n border that is a continuation 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 ...

, Turkey geologically is part of the great

Alpide belt The Alpide belt or Alpine-Himalayan orogenic belt,K.M. Storetvedt, K. M., ''The Tethys Sea and the Alpine-Himalayan orogenic belt; mega-elements in a new global tectonic system,'' Physics of the Earth and Planetary Interiors, Volume 62, Issues 1 ...

that extends from the Atlantic Ocean to the Himalaya Mountains. This belt was formed during the

Cenozoic Era 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 configu ...

(about 66 to 1.6 million years ago), as the Arabian, African, and

Indian Indian or Indians may refer to: Peoples South Asia * Indian people, people of Indian nationality, or people who have an Indian ancestor ** Non-resident Indian, a citizen of India who has temporarily emigrated to another country * South Asia ...

continental plate Continental may refer to: Places * Continent, the major landmasses of Earth * Continental, Arizona, a small community in Pima County, Arizona, US * Continental, Ohio, a small town in Putnam County, US Arts and entertainment * ''Continental'' (a ...

s began to collide with 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 an ...

. This process is still at work today as the African Plate converges with the Eurasian Plate and the

Anatolian Plate The Anatolian Plate is a continental tectonic plate comprising most of the Anatolia (Asia Minor) peninsula (and the country of Turkey). To the east, the East Anatolian Fault, a left lateral transform fault, forms a boundary with the Arabian ...

escapes towards the west and southwest along strike-slip faults. These are the

North Anatolian Fault Zone The North Anatolian Fault (NAF) ( tr, Kuzey Anadolu Fay Hattı) is an active right-lateral strike-slip fault in northern Anatolia, and is the transform boundary between the Eurasian Plate and the Anatolian Plate. The fault extends westward f ...

, which forms the present day plate boundary of Eurasia near the Black Sea coast and, the East Anatolian Fault Zone, which forms part of the boundary of the North Arabian Plate in the southeast. As a result of this

plate tectonics Plate tectonics (from the la, label= Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of larg ...

configuration, Turkey is one of the world's more active earthquake and volcanic regions. The Anatolian Plate, together with the Aegean-

Peloponnesus The Peloponnese (), Peloponnesus (; el, Πελοπόννησος, Pelopónnēsos,(), or Morea is a peninsula and geographic region in southern Greece. It is connected to the central part of the country by the Isthmus of Corinth land bridge wh ...

block, is located near the centre of a very wide region, including the

with the adjacent

Zagros Mountains The Zagros Mountains ( ar, جبال زاغروس, translit=Jibal Zaghrus; fa, کوه‌های زاگرس, Kuh hā-ye Zāgros; ku, چیاکانی زاگرۆس, translit=Çiyakani Zagros; Turkish: ''Zagros Dağları''; Luri: ''Kuh hā-ye Zāgr ...

and central

, that moves in a circulatory pattern at a relatively fast rate of 20 mm/yr. The rate of this counter-clockwise motion increases near the Hellenic Trench system south of Turkey and decreases away from it (i.e. the Eurasian and African plates move at a rate of 5 mm/yr), resulting in internal deformations in several areas, including central and eastern Anatolia, south-western Aegean-Peloponnesus,

Lesser Caucasus The Lesser Caucasus, also called Caucasus Minor, is the second of the two main mountain ranges of Caucasus mountains, of length about . The western portion of the Lesser Caucasus overlaps and converges with east Turkey and northwest Iran. It runs ...

, and central Iran. The dominant process in the region is the subduction of the African Plate beneath the Hellenic Trench, and the deformation in the entire African-Arabian-Eurasian collision zone is most likely driven by the slab roll-back of the subducting African Plate in the East Mediterranean. This process is further fuelled by slab-pull forces in the

Makran Trench 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 of Pakistan and the southeastern coast of Iran. In this region the ocean ...

in the

Gulf of Oman The Gulf of Oman or Sea of Oman ( ar, خليج عمان ''khalīj ʿumān''; fa, دریای عمان ''daryâ-ye omân''), also known as Gulf of Makran or Sea of Makran ( ar, خلیج مکران ''khalīj makrān''; fa, دریای مکرا� ...

where the Arabian Plate is subducting under Eurasia. A response to this tectonic maelstrom is the rifting in the Red Sea and Gulf of Aden which will separate Arabia from Africa. The

tomography Tomography is imaging by sections or sectioning that uses any kind of penetrating wave. The method is used in radiology, archaeology, biology, atmospheric science, geophysics, oceanography, plasma physics, materials science, astrophysics, ...

of the velocity propagation distributions of the P__n

seismic waves A seismic wave is a wave of acoustic energy that travels through the Earth. It can result from an earthquake, volcanic eruption, magma movement, a large landslide, and a large man-made explosion that produces low-frequency acoustic energy. ...

both in an isotropic and

anisotropic Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...

conditions, compared with the lateral variations of that velocity has highlighted the physical properties of the uppermost mantle and crustal thickness of the Earth. A study analyzed 700 earthquakes occurred in Turkey from 1999 to 2010 with magnitude degree major than 4.0 and the related 50.000 Pn first arrivals recorded by 832 seismic stations at a distance range of 180–1500 km from the

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

. The tomography highlighted that "Pn velocities are found to be lowest in eastern Turkey (<7.6 km s-1) and highest in the eastern

and Zagros Suture (>8.3 km s-1). Large Pn anisotropy is observed in the Aegean, central Anatolia and along the southern coast of Anatolia. ..Large crustal thicknesses are observed along the

Dinarides The Dinaric Alps (), also Dinarides, are a mountain range in Southern and Southcentral Europe, separating the continental Balkan Peninsula from the Adriatic Sea. They stretch from Italy in the northwest through Slovenia, Croatia, Bosnia and Herz ...

- Hellenides and along the southern coast of Anatolia."

Rocks

Many of the rocks exposed in Turkey were formed long before this process began. Turkey contains outcrops of

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of th ...

rocks, (more than 540 million years old). During the

Mesozoic era The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

(about 250 to 66 million years ago) a large ocean (

Tethys Ocean The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...

), floored by oceanic lithosphere existed in-between the

supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leav ...

s of

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final sta ...

and

Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...

(which lay to the south and north respectively). This large oceanic plate was consumed at

subduction zone Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

s. At the subduction trenches the sedimentary rock layers that were deposited within the prehistoric Tethys Ocean were folded, faulted and tectonically mixed with huge blocks of crystalline basement rocks of the oceanic lithosphere. These blocks form a very complex mixture or

mélange In geology, a mélange is a large-scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix. The mélange typically cons ...

of rocks that include mainly

serpentinite Serpentinite is a rock composed predominantly of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called ''serpentine'' or ''s ...

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

dolerite Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...

, and

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a ...

. The Eurasian margin, now preserved in the Pontides (the

Pontic Mountains The Pontic Mountains or Pontic Alps (Turkish language, Turkish: ''Kuzey Anadolu Dağları'', meaning North Anatolian Mountains) form a mountain range in northern Anatolia, Turkey. They are also known as the ''Parhar Mountains'' in the local Turki ...

along the Black Sea coast), is thought to have been geologically similar to the Western Pacific region today. Volcanic arcs and

back-arc basin A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most o ...

s formed and were emplaced onto Eurasia as

ophiolite An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed above sea level and often emplaced onto continental crustal rocks. The Greek word ὄφις, ''ophis'' (''snake'') is found ...

s as they collided with

microcontinent Continental crustal fragments, partly synonymous with microcontinents, are pieces of continents that have broken off from main continental masses to form distinct islands that are often several hundred kilometers from their place of origin. Caus ...

s (literally relatively small plates of continental lithosphere). These microcontinents had been pulled away from the Gondwanan continent further south. Turkey is therefore made up from several different prehistorical microcontinents. During 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 configu ...

(Tertiary about 66 to 1.6 million years) folding, faulting and uplifting, accompanied by volcanic activity and intrusion of igneous rocks was related to major continental collision between the larger Arabian and Eurasian plates.Robertson & Dixon, 1984

Earthquakes

Turkey's most severe earthquake in the twentieth century occurred in

Erzincan Erzincan (; ku, Erzîngan), historically Yerznka ( hy, Երզնկա), is the capital of Erzincan Province in Eastern Turkey. Nearby cities include Erzurum, Sivas, Tunceli, Bingöl, Elazığ, Malatya, Gümüşhane, Bayburt, and Giresun. The ...

on the night of 1939-12-27; it devastated most of the city and caused an estimated 30,000 deaths. Earthquakes of moderate intensity often continue with sporadic aftershocks over periods of several days or even weeks. Seismicity in Turkey is more likely to happen in the North Anatolian Fault Zone, East Anatolian Fault Zone and in the subduction region of the Aegean Plate between the Anatolian plate.

External links

1:25,000 scale fault maps (click the square to see a map if there are faults)

Seismic Risk Map (requires logon with Turkish ID)

Notes

References

*Bergougnan, H. (1975) Dispositif des ophiolites nord-est anatoliennes, origine des nappes ophiolitiques et sud-pontiques, jeu de la faille nord-anatolienne. Comptes Rendus de l'Académie des Sciences, Série D: Sciences Naturelles, 281: 107–110. *Bozkurt, E. and Satir, M. (2000) The southern Menderes Massif (western Turkey); geochronology and exhumation history. Geological Journal, 35: 285–296. *Kaymakci, N., 2000. Tectono-stratigraphical evolution of the Çankırı basin (Central Anatolia, Turkey) (Vol. 190, pp. 1–247). Utrecht University. , url = http://www.itc.nl/library/papers_2000/phd/kaymakci.pdf *Kaymakci, N., Inceöz, M., Ertepinar, P. and Koç, A. 2010. Late Cretaceous to recent kinematics of SE Anatolia (Turkey) In Sosson, M. Kaymakci, N., Stephenson, R., Starostenko, V. and Bergerat, F. (Eds.) Sedimentary basin tectonics from the Black Sea and Caucasus to the Arabian Platform. Geological Society London Special Issue No. 340, 409-435. , url = http://www.metu.edu.tr/~kaymakci/papers/17_Kaymakci%202010_GSL340_SE_Anatolia.pdf *Reilinger, R.; McClusky, S.; Vernant, P.; Lawrence, S.; Ergintav,S.; Çakmak, R. 2006. GPS constraints on continental deformation in the Africa‐Arabia‐Eurasia continental collision zone and implications for the dynamics of plate interactions. Journal of Geophysical Research: Solid Earth 111/B5 , url = https://www.researchgate.net/profile/Semih_Ergintav/publication/224962277_Reilinger_R._et_al._GPS_constraints_on_continental_deformation_in_the_Africa-Arabia-Eurasia_continental_collision_zone_and_implications_for_the_dynamics_of_plate_interaction._J._Geophys._Res._111_B05411/links/0912f51396974ee03d000000.pdf , accessdate = July 2016 *Robertson, A. and Dixon, J.E.D. (1984) Introduction: aspects of the geological evolution of the Eastern Mediterranean. In: Dixon and Robertson (Editors), The Geological Evolution of the Eastern Mediterranean. Geological Society, London, Special Publications, 17, 1–74. *Ustaömer, T. and Robertson, A. (1997) Tectonic-sedimentary evolution of the north Tethyan margin in the Central Pontides of northern Turkey. In: A.G. Robinson (Editor), Regional and Petroleum Geology of the Black Sea and Surrounding Region. AAPG Memoir, 68, Tulsa, Oklahoma, 255–290. * *