Geology of Turkey
Encyclopedia
Turkey
's varied landscapes are the product of a wide variety of tectonic processes that have shaped Anatolia
over millions of years and continue today as evidenced by frequent earthquakes and occasional volcanic eruptions.
, 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 Ergene Plain in Thrace
, extending along rivers that discharge into the Aegean Sea
or the Sea of Marmara
, and to a few narrow coastal strips along the Black Sea
and Mediterranean Sea
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
and Adana
, and the valley floors of the Gediz River
and the Büyük Menderes River, 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
, Azerbaijan
, and Iran
. Turkey's highest peak, Mount Ararat
(Ağrı Dağı)—about 5,166 meters high—is situated near the point where the boundaries of the four countries meet.
stuck together by younger igneous, volcanic and sedimentary rocks.
n border that is a continuation of the Arabian Plate
, Turkey geologically is part of the great Alpine belt that extends from the Atlantic Ocean to the Himalaya Mountains. This belt was formed during the Tertiary Period (about 65 million to 1.6 million B.C.), as the Arabian, African
, and Indian continental plates began to collide with the Eurasian Plate
. This process is still at work today as the African Plate converges with the Eurasian Plate and the Anatolian Plate
escapes towards the west and southwest along strike-slip faults. These are the North Anatolian Fault Zone, 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
configuration, Turkey is one of the world's more active earthquake and volcano regions.
rocks, (more than 540 million years old).
During the Mesozoic era (about 250 to 65 million years ago) a large ocean (Tethys Ocean
), floored by oceanic lithosphere existed in-between the supercontinent
s of Gondwana
and Laurasia
(which lay to the south and north respectively). This large oceanic plate was consumed at subduction zones. At the subduction trenches the sedimentary rock layers that were deposited within the prehistoric Tethys Ocean buckled, 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
of rocks that include mainly serpentinite
, basalt
, dolerite, and chert
. The Eurasian margin, now preserved in the Pontides (the Pontic Mountains
along the Black Sea coast), is thought to have been geologically similar to the Western Pacific region today. Volcanic arc
s and back-arc basin
s formed and were emplaced onto Eurasia as ophiolites as they collided with microcontinents (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
(Tertiary about 65 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.
on the night of 1939-12-27; it devastated most of the city and caused an estimated 160,000 deaths. Earthquakes of moderate intensity often continue with sporadic aftershocks over periods of several days or even weeks. The most earthquake-prone part of Turkey is an arc-shaped region stretching from the general vicinity of Kocaeli
to the area north of Lake Van
on the border with Armenia
and Georgia
.
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
's varied landscapes are the product of a wide variety of tectonic processes that have shaped Anatolia
Anatolia
Anatolia is a geographic and historical term denoting the westernmost protrusion of Asia, comprising the majority of the Republic of Turkey...
over millions of years and continue today as evidenced by frequent earthquakes and occasional volcanic eruptions.
Background
Turkey's terrain is structurally complex. A central massif composed of uplifted blocks and downfolded troughsTrough (geology)
In geology, a trough generally refers to a linear structural depression that extends laterally over a distance, while being less steep than a trench.A trough can be a narrow basin or a geologic rift....
, 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 Ergene Plain in Thrace
Thrace
Thrace is a historical and geographic area in southeast Europe. As a geographical concept, Thrace designates a region bounded by the Balkan Mountains on the north, Rhodope Mountains and the Aegean Sea on the south, and by the Black Sea and the Sea of Marmara on the east...
, extending along rivers that discharge into the Aegean Sea
Aegean Sea
The Aegean Sea[p] is an elongated embayment of the Mediterranean Sea located between the southern Balkan and Anatolian peninsulas, i.e., between the mainlands of Greece and Turkey. In the north, it is connected to the Marmara Sea and Black Sea by the Dardanelles and Bosporus...
or the Sea of Marmara
Sea of Marmara
The Sea of Marmara , also known as the Sea of Marmora or the Marmara Sea, and in the context of classical antiquity as the Propontis , is the inland sea that connects the Black Sea to the Aegean Sea, thus separating Turkey's Asian and European parts. The Bosphorus strait connects it to the Black...
, and to a few narrow coastal strips along the Black Sea
Black Sea
The Black Sea is bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and the Aegean seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects that sea to the Aegean...
and Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
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
Antalya
Antalya is a city on the Mediterranean coast of southwestern Turkey. With a population 1,001,318 as of 2010. It is the eighth most populous city in Turkey and country's biggest international sea resort.- History :...
and Adana
Adana
Adana is a city in southern Turkey and a major agricultural and commercial center. The city is situated on the Seyhan River, 30 kilometres inland from the Mediterranean, in south-central Anatolia...
, and the valley floors of the Gediz River
Gediz River
-Name:The ancient name of the river was Hermos or Hermus.The name of the river Gediz may be related to the Lydian proper name Cadys; Gediz is also the name of a town near the river's sources. The name "Gediz" may also be encountered as a male name in Turkey.-Ancient geography:The Hermos separated...
and the Büyük Menderes River, and some interior high plains in Anatolia, mainly around Tuz Gölü
Lake Tuz
Lake Tuz is the second largest lake in Turkey with its surface area and one of the largest hypersaline lakes in the world. It is located in the Central Anatolia Region, northeast of Konya, south-southeast of Ankara and northwest of Aksaray.-Geography:...
(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
Armenia , officially the Republic of Armenia , is a landlocked mountainous country in the Caucasus region of Eurasia...
, Azerbaijan
Azerbaijan
Azerbaijan , officially the Republic of Azerbaijan is the largest country in the Caucasus region of Eurasia. Located at the crossroads of Western Asia and Eastern Europe, it is bounded by the Caspian Sea to the east, Russia to the north, Georgia to the northwest, Armenia to the west, and Iran to...
, and Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...
. Turkey's highest peak, Mount Ararat
Mount Ararat
Mount Ararat is a snow-capped, dormant volcanic cone in Turkey. It has two peaks: Greater Ararat and Lesser Ararat .The Ararat massif is about in diameter...
(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 of the problem of reconstructing how the region has been tectonically assembled by plate motions. Turkey can be thought of as a collage of different pieces (possibly terranes) of ancient continental and oceanic lithosphereLithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...
stuck together by younger igneous, volcanic and sedimentary rocks.
Plate tectonics
Except for a relatively small portion of its territory along the SyriaSyria
Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....
n border that is a continuation of the Arabian Plate
Arabian Plate
The Arabian Plate is one of three tectonic plates which have been moving northward over millions of years and colliding with the Eurasian Plate...
, Turkey geologically is part of the great Alpine belt that extends from the Atlantic Ocean to the Himalaya Mountains. This belt was formed during the Tertiary Period (about 65 million to 1.6 million B.C.), as the Arabian, African
African Plate
The African Plate is a tectonic plate which includes the continent of Africa, as well as oceanic crust which lies between the continent and various surrounding ocean ridges.-Boundaries:...
, and Indian continental plates began to collide with the Eurasian Plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
. This process is still at work today as the African Plate converges with the Eurasian Plate and the Anatolian Plate
Anatolian Plate
The Anatolian Plate is a continental tectonic plate consisting primarily of the country of Turkey.The easterly side is a boundary with the Arabian Plate, the East Anatolian Fault, a left lateral transform fault....
escapes towards the west and southwest along strike-slip faults. These are the North Anatolian Fault Zone, which forms the present day plate boundary of Eurasia near the Black Sea coast and, the East Anatolian Fault
East Anatolian Fault
The East Anatolian Fault is a major strike-slip fault zone in eastern Turkey. It forms the transform type tectonic boundary between the Anatolian Plate and the northward-moving Arabian Plate. The difference in the relative motions of the two plates is manifest in the left lateral motion along the...
Zone, which forms part of the boundary of the North Arabian Plate in the southeast. As a result of this plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
configuration, Turkey is one of the world's more active earthquake and volcano regions.
Rocks
Many of the rocks exposed in Turkey were formed long before this process began. Turkey contains outcrops of PrecambrianPrecambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
rocks, (more than 540 million years old).
During the Mesozoic era (about 250 to 65 million years ago) a large ocean (Tethys Ocean
Tethys Ocean
The Tethys Ocean was an ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.-Modern theory:...
), floored by oceanic lithosphere existed in-between the supercontinent
Supercontinent
In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:...
s of Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
and Laurasia
Laurasia
In paleogeography, Laurasia was the northernmost of two supercontinents that formed part of the Pangaea supercontinent from approximately...
(which lay to the south and north respectively). This large oceanic plate was consumed at subduction zones. At the subduction trenches the sedimentary rock layers that were deposited within the prehistoric Tethys Ocean buckled, 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
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 consists of a jumble of large blocks of varied lithologies...
of rocks that include mainly serpentinite
Serpentinite
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle...
, basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
, dolerite, and chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
. The Eurasian margin, now preserved in the Pontides (the Pontic Mountains
Pontic Mountains
The Pontic Mountains form a mountain range in Northern Turkey, also known as the Parhar mountains in the local Turkish and Pontic Greek languages. The term "Parhar" originates from the Hittite word meaning "high" or "summit"....
along the Black Sea coast), is thought to have been geologically similar to the Western Pacific region today. Volcanic arc
Volcanic arc
A volcanic arc is a chain of volcanoes positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench...
s and back-arc basin
Back-arc basin
Back-arc basins are geologic features, submarine basins associated with island arcs and subduction zones.They are found at some convergent plate boundaries, presently concentrated in the Western Pacific ocean. Most of them result from tensional forces caused by oceanic trench rollback and the...
s formed and were emplaced onto Eurasia as ophiolites as they collided with microcontinents (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
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
(Tertiary about 65 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.
Earthquakes
Present-day earthquakes range from barely perceptible tremors to major movements measuring five or higher on the open-ended Richter scale. Turkey's most severe earthquake in the twentieth century occurred in ErzincanErzincan
-Trivia:Erzincan has the largest man made of Portrait of Atatürk, located north of the city, 176m×43m. It covers 7,500 square meter. Turkish Army made it 1982, in 29 days by 3,000 soldier, 100 tons of black and white paint was used...
on the night of 1939-12-27; it devastated most of the city and caused an estimated 160,000 deaths. Earthquakes of moderate intensity often continue with sporadic aftershocks over periods of several days or even weeks. The most earthquake-prone part of Turkey is an arc-shaped region stretching from the general vicinity of Kocaeli
Izmit
İzmit is a city in Turkey, administrative center of Kocaeli Province as well as the Kocaeli Metropolitan Municipality. It is located at the Gulf of İzmit in the Sea of Marmara, about east of Istanbul, on the northwestern part of Anatolia. The city center has a population of 294.875...
to the area north of Lake Van
Lake Van
Lake Van is the largest lake in Turkey, located in the far east of the country in Van district. It is a saline and soda lake, receiving water from numerous small streams that descend from the surrounding mountains. Lake Van is one of the world's largest endorheic lakes . The original outlet from...
on the border with Armenia
Armenia
Armenia , officially the Republic of Armenia , is a landlocked mountainous country in the Caucasus region of Eurasia...
and Georgia
Georgia (country)
Georgia is a sovereign state in the Caucasus region of Eurasia. Located at the crossroads of Western Asia and Eastern Europe, it is bounded to the west by the Black Sea, to the north by Russia, to the southwest by Turkey, to the south by Armenia, and to the southeast by Azerbaijan. The capital of...
.
Further reading
- Brinkmann, Roland, 1976, Geology of Turkey, Elsevier Scientific Pub. Co ISBN 0444998330
- Higgins, MD and Higgins, RA, 1996,*A Geological Companion to Greece and the Aegean Cornell University Press. ISBN 0801433371