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The main points that are discussed in the
The main points that are discussed in the geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
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 ...
include the study of the geological and structural units or zones; stratigraphy
Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks.
Stratigrap ...
; magmatism
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of ...
and igneous rocks; 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 i ...
series and ultramafic rocks; and orogenic events in Iran.
Geological and structural units of Iran
Considering geological and structural units of Iran, three main structural units or zones could be distinguished in Iran. These units or zones are separated from each other byophiolite
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 i ...
–bearing sutures. Other criteria such as structural style, crustal character and age of basement consolidation, age and intensity of deformation, age and nature of magmatism, are used to subdivide these major zones into smaller elements. The three major units and their main constituents could be defined as the southern, central and northern units. The southern unit has a crystalline basement consolidated in the 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 the ...
time and a platform
Platform may refer to:
Technology
* Computing platform, a framework on which applications may be run
* Platform game, a genre of video games
* Car platform, a set of components shared by several vehicle models
* Weapons platform, a system or ...
–type Paleozoic development and comprises the Zagros folded belt, southern and southwestern parts of the Zagros. This section made a part of the Arabian Plate that was located on the margin of Rodinia
Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago.
were probably ...
and Pannotia
Pannotia (from Greek: '' pan-'', "all", '' -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent ...
in the Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago.
It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is ...
, and 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 stages ...
in the Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ' ...
and Mesozoic
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 Cretaceo ...
. The central unit, which comprises the central Iran and the Alborz, is interpreted as an assemblage of fragments that were in the vicinity of the Arabian Plate and formed a marginal section of Rodinia and Pannotia in the Neoproterozoic and of Gondwana in the Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
, Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...
, Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
and Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
. These fragments were detached from Gondwana in the Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
. They were submerged, moved northwards, and were finally attached to the Eurasian section of the northern supercontinent 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 Pan ...
in the Late Triassic
The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...
. These fragments or microplates were fused together and made the Iranian Plate
The Iranian Plate is a small tectonic plate thought to underlie the Persian plateau, covering the modern-day countries of Iran and Afghanistan, and parts of Iraq and Pakistan. It is compressed between the Arabian Plate to the southwest, the E ...
which was rejoined by Gondwanic Afro-Arabia in the Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
. As Afro-Arabia moved northwards towards Eurasia
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...
, 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 collidin ...
ultimately collided with the Iranian Plate in the Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
. Finally there is the northern unit which is separated from the central unit by the North Iran Suture. It is characterized by continental crust including remnants of more or less cratonized former Paleozoic oceanic crust that seems to reflect the Paleotethys
The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; exi ...
. The northern unit represents a marginal strip of the Hercynian realm of Central Asia- broadly overlapped by the Alpine realm. It was deformed and largely consolidated by the Early Cimmerian folding and the Late Alpine folding. The northern unit comprises the South Caspian Depression and the Kopet Dagh
The Köpet Dag, Kopet Dagh, or Koppeh Dagh ( tk, Köpetdag; fa, کپهداغ), also known as the Turkmen-Khorasan Mountain Range, is a mountain range on the border between Turkmenistan and Iran that extends about along the border southeast o ...
Range. These three main structural units are divided into some smaller geological and structural subdivisions which include the following zones:
Zagros
This zone extends fromBandar Abbas
Bandar Abbas or Bandar-e ‘Abbās ( fa, , , ), is a port city and capital of Hormozgān Province on the southern coast of Iran, on the Persian Gulf. The city occupies a strategic position on the narrow Strait of Hormuz (just across from Musan ...
in the south to Kermanshah
Kermanshah ( fa, کرمانشاه, Kermânšâh ), also known as Kermashan (; romanized: Kirmaşan), is the capital of Kermanshah Province, located from Tehran in the western part of Iran. According to the 2016 census, its population is 946,68 ...
in the northwest and continues through to Iraq
Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq ...
. Zagros is in fact the northeastern edge of the Arabian Plate. Some important features of Zagros include: Absence of magmatic and metamorphic events after Triassic, and low abundance of the outcrops of Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ' ...
rocks. Structurally, it consists of large anticline
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...
s and small syncline
In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimpose ...
s and continuous marine sedimentation from the Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
to the Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
. On the whole, a sequence 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 the ...
to Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Recent time in the
Volcanic rocks of andesitic-basaltic composition accompany Upper Paleozoic sedimentary strata in many areas all over Iran. Basaltic rocks associated with Jeyrud Formation of Upper
The effects of this orogenic episode in Iran can be traced from the Late Devonian. Due to the scarcity of magmatism, metamorphism, and folding related to this episode, the role of the
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Creative Commons Attribution 4.0 International License
{{Asia topic, Geology of
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 Zāgro ...
. 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 ...
was formed by the collision of two tectonic plates — the Iranian Plate
The Iranian Plate is a small tectonic plate thought to underlie the Persian plateau, covering the modern-day countries of Iran and Afghanistan, and parts of Iraq and Pakistan. It is compressed between the Arabian Plate to the southwest, the E ...
and 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 collidin ...
. This collision primarily happened during the Miocene and folded the entire rocks that had been deposited from the Carboniferous to the Miocene in the geosyncline
A geosyncline (originally called a geosynclinal) is an obsolete geological concept to explain orogens, which was developed in the late 19th and early 20th centuries, before the theory of plate tectonics was envisaged. Şengör (1982), p. 11 A geo ...
in front of the Iranian Plate. The process of collision continues to the present and as the Arabian Plate is being pushed against the Iranian Plate, the Zagros Mountains and the Iranian Plateau
The Iranian plateau or Persian plateau is a geological feature in Western Asia, Central Asia, and South Asia. It comprises part of the Eurasian Plate and is wedged between the Arabian Plate and the Indian Plate; situated between the Zagros ...
are getting higher and higher. The Zagros mountain range, itself, has a totally sedimentary origin and is made primarily of limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
. In the Elevated Zagros or the Higher Zagros, the Paleozoic rocks could be found mainly in the upper and higher sections of the peaks of the Zagros Mountains along the Zagros main fault. On the both sides of this fault, there are Mesozoic
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 Cretaceo ...
rocks, a combination of Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
and Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
rocks that are surrounded by Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
rocks on the both sides. The Folded Zagros (the mountains south of the Elevated Zagros and almost parallel to the main Zagros fault) is formed mainly of Tertiary
Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago.
The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...
rocks, with the Paleogene
The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...
rocks south of the Cretaceous rocks and then the Neogene
The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...
rocks south of the Paleogene rocks.
Sanandaj–Sirjan
This zone is located to the south-southwest of Central Iran and the northeastern edge of Zagros range. In the north and northeast, this zone is separated from Central Iran by depressions likeLake Urmia
Lake Urmia;
az, اۇرمۇ گؤلۆ, script=Arab, italic=no, Urmu gölü;
ku, گۆلائوو رمیەیێ, Gola Ûrmiyeyê;
hy, Ուրմիա լիճ, Urmia lich;
arc, ܝܡܬܐ ܕܐܘܪܡܝܐ is an endorheic salt lake in Iran. The lake is ...
, Gavkhouni
Gavkhouni ( fa, گاوخونی, Gāwxuni) also written as ''Gawkhuni'' or ''Batlaq-e-Gavkhuni'', located in the Iranian Plateau in central Iran, east of city of Isfahan, is the terminal basin of the Zayandeh River. Gavkhouni is a salt marsh with ...
and faults like Shahr-e-Babak and Abadeh, and to the south-southwest by the main thrust fault of Zagros. A striking feature of this zone is the presence of immense volumes of magmatic and metamorphic rocks of Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ' ...
and Mesozoic
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 Cretaceo ...
eras. As far as the trends, and particularly the folding style is concerned, some researchers consider the Sanandaj–Sirjan Zone as being similar to Zagros; however, considerable differences exist in rock types, magmatism, metamorphism, and orogenic events. There are some similarities between Sanandaj
Sanandaj (Persian: سنندج, ; ku, سنە, Sine, often romanized as Senneh, is the capital of Kurdistan Province in Iran. With a population of 414,069, Sanandaj is the twenty third largest city in Iran and the second largest Kurdish city. San ...
–Sirjan
Sirjan ( fa, سيرجان, also Romanized as Sīrjān; formerly Sa‘īdābād) is a city and the capital of Sirjan County, Kerman Province,in the south of Iran. According to the 2016 census, its population was 324,103 in 95,357 families. Sirjan ...
and Central Iran.
Sahand–Bazman Volcanic Belt
This volcanic belt, which is usually called theCentral Iranian Range
The Sahand-Bazman Volcanic and Plutonic Belt or the Sahand-Bazman Igneous Arc or the Central Iranian Range is a mountain range that is made by (both extrusive and intrusive) igneous and pyroclastic rocks. Located East and almost parallel to the Z ...
, runs east and almost parallel to the Sanandaj–Sirjan Zone, and owes its existence to the widespread and intensive volcanic activity which developed on the Iranian plate from the Upper Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
to Recent time. The peak of this volcanism happened in the Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
. The Sahand
Sahand ( fa, سهند), is a massive, heavily eroded stratovolcano in East Azerbaijan Province, northwestern Iran. At , it is the highest mountain in the province of East Azarbaijan.
Sahand is one of the highest mountains in Iranian Azerbaijan, ...
-Bazman
Bazman ( fa, بزمان, also known as Kuh-e Bazman) is a dormant stratovolcano in a remote desert region of Sistan and Baluchestan Province in south-eastern Iran. A 500-m-wide crater caps the summit of the dominantly andesitic-dacitic volcano ...
volcanic belt is supposed to have resulted from the collision of the Arabian and Central Iranian continental plate margins. It is represented by sub-alkaline volcanics that vary in composition from basaltic through andesitic to rhyolitic composition.
Central Iran
Located in a triangle in the middle of Iran, Central Iran is one of the most important and complicated structural zones in Iran. In this zone, rocks of all ages, fromPrecambrian
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 the ...
to Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
, and several episodes of orogeny, metamorphism
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...
, and magmatism
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of ...
can be recognized. Central Iran in a broad sense, comprising the whole area between the North and South Iranian ranges. Within the Iranian plate the Central-East Iran microplate is bordered by the Great Kavir Fault in the north, by the Nain–Baft
Baft ( fa, بافت, also romanized as Bāft) is a city and capital of Baft County, Kerman Province, Iran. Baft is located southwest of Kerman. At the 2006 census, its population was 35,008, in 8,265 families. Notably, Baft is one of the highest ...
Fault in the west and southwest and by the Harirud Fault in the east. It is surrounded by the Upper Cretaceous to Lower Eocene ophiolite and ophiolitic melange. The microplate consists of different structural components; Kerman
Kerman ( fa, كرمان, Kermân ; also romanization of Persian, romanized as Kermun and Karmana), known in ancient times as the satrapy of Carmania, is the capital city of Kerman Province, Iran. At the 2011 census, its population was 821,394, in ...
-Tabas
Tabas ( fa, طبس, also Romanized as Ṭabas), formerly known as Golshan, is the capital city of Tabas County in South Khorasan Province of Iran. At the 2011 census, its population was 35,150, in 9,903 families.
Tabas is located in central Iran, ...
Block, Yazd
Yazd ( fa, یزد ), formerly also known as Yezd, is the capital of Yazd Province, Iran. The city is located southeast of Isfahan. At the 2016 census, the population was 1,138,533. Since 2017, the historical city of Yazd is recognized as a Worl ...
Block and Anarak
Anarak ( fa, انارک, also Romanized as Anārak) is a city and capital of Anarak District, in Nain County, Isfahan Province, Iran. At the 2006 census, its population was 1,285, in 462 families. It is situated at an altitude of .
Anarak is l ...
-Khur
The Indian wild ass (''Equus hemionus khur''), also called the Indian onager or, in the local Gujarati language, Ghudkhur and Khur, is a subspecies of the onager native to South Asia.
It is currently listed as Near Threatened by IUCN. The pr ...
Block.
Eastern Iran
Eastern Iran can be divided into two parts: Lut Block and Flysch Zone (flysch
Flysch () is a sequence of sedimentary rock layers that progress from deep-water and turbidity flow deposits to shallow-water shales and sandstones. It is deposited when a deep basin forms rapidly on the continental side of a mountain building ep ...
or coloured melange of Zabol–Baluch Zone). Located to the west of Zabol–Baluch Zone, Lut Block is the main body of Eastern Iran. Lut Block extends for about in a north–south direction. It is bounded in the north by Dorooneh fault and in the south by Jazmurian depression. In the east, it is separated from Flysch Zone by the Nehbandan Fault, whereas the western boundary with Central Iran is Nayband fault and Shotori Mountains. The oldest units include upper Precambrian Lower Cambrian schists overlain by Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
limestone and other Paleozoic sedimentary rocks. Flysch Zone (Zabol–Baluch) is located between Lut Block to the west and Helmand
Helmand (Pashto/Dari: ; ), also known as Hillmand, in ancient times, as Hermand and Hethumand, is one of the 34 provinces of Afghanistan, in the south of the country. It is the largest province by area, covering area. The province contains 13 ...
(in Afghanistan
Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...
) to the east. In contrast to Lut Block, the Flysch Zone is highly deformed and tectonized and consists of thick deep-sea sediments like argillaceous and silicic shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...
s, radiolarite
Radiolarite is a siliceous, comparatively hard, fine-grained, chert-like, and homogeneous sedimentary rock that is composed predominantly of the microscopic remains of radiolarians. This term is also used for indurated radiolarian oozes and ...
, and pelagic limestone and volcanic rocks such as basalt
Basalt (; ) is an aphanite, 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 planetary surface, surface of a terrestrial ...
, spilitic basalt, diabase
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-graine ...
, andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...
, dacite
Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...
, rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...
, and subordinate serpentinized ultramafic rocks. The basement is likely composed of an oceanic crust. Most rock units in this zone fall into three main groups: flyschoid
Flysch () is a sequence of sedimentary rock layers that progress from deep-water and turbidity flow deposits to shallow-water shales and sandstones. It is deposited when a deep basin forms rapidly on the continental side of a mountain building e ...
sediments; volcanic, volcanosedimentary, and intrusive rocks; and ophiolitic series.
Southeastern Iran or Makran
Southeastern Iran orMakran
Makran ( fa, مكران), mentioned in some sources as Mecran and Mokrān, is the coastal region of Baluchistan. It is a semi-desert coastal strip in Balochistan, in Pakistan and Iran, along the coast of the Gulf of Oman. It extends westwards, ...
zone is located to the south of Jazmurian depression. Its western boundary is Minab Fault; to the south, it is restricted by 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 ...
, and to the east, it extends into 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 ...
. The northern part is characterized by dominance of east–west trending faults, Bashagard fault being the most important one. Along these faults lies large section of ophiolite series. The oldest rocks in this zone are the ophiolites of Late Cretaceous–Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
overlain by a thick sequence (about 5,000 m) of sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
, shale, and marl
Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae.
Marl makes up the lower part o ...
. The whole sequence is deformed prior to Early Miocene. Thick sequence of Neogene
The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...
rock units, in excess of 5,000 m, covers the older series.
Kopet Dagh
The northeastern active fold belt of Iran, theKopet Dagh
The Köpet Dag, Kopet Dagh, or Koppeh Dagh ( tk, Köpetdag; fa, کپهداغ), also known as the Turkmen-Khorasan Mountain Range, is a mountain range on the border between Turkmenistan and Iran that extends about along the border southeast o ...
, is formed on the Hercynian metamorphosed basement at the southwestern margin of the Turan Platform. The belt is composed of about 10 kilometres of Mesozoic and Tertiary sediments (mostly carbonates) and, like the Zagros, was folded into long linear northwest-southeast trending folds during the last phase of the Alpine Orogeny, in the Miocene and Plio-Pleistocene time. No magmatic rocks are exposed in Kopet Dagh except for those in the basement in the Aghdarband and some Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
basic dikes. This basin was located in the northeastern Iran. From Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
, it was covered with a vast continental shelf sea. In this period of time and due to transgression as well as rapid subsidence basin, the western part became deeper. In this basin, a thick sequence of continuous marine and continental sediments was deposited (about 10 km). No major sedimentary gap or volcanic activities during Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
to Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
have ever been reported. This sedimentary complex provides suitable conditions for accumulation of hydrocarbons. Kopet Dagh sedimentary rocks were placed in their current position due to uplifting at the end of the Miocene. The Kopet Dag Range, itself, is made chiefly of Cretaceous rocks with a smaller portion of Jurassic rocks in the southeastern parts. The mountains were mainly formed in the Miocene during the Alpine orogeny. As the Tethys Sea
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 ...
was closed and the Arabian Plate collided with the Iranian Plate and was pushed against it, and with the clockwise rotation of the Eurasian Plate towards the Iranian Plate and their final collision, the Iranian Plate was pressed against the Turan Platform. This collision folded the entire rocks that had been deposited in this geosyncline
A geosyncline (originally called a geosynclinal) is an obsolete geological concept to explain orogens, which was developed in the late 19th and early 20th centuries, before the theory of plate tectonics was envisaged. Şengör (1982), p. 11 A geo ...
or basin from the Jurassic to the Miocene and formed the Kopet Dag Mountains.
Alborz
TheAlborz
The Alborz ( fa, البرز) range, also spelled as Alburz, Elburz or Elborz, is a mountain range in northern Iran that stretches from the border of Azerbaijan along the western and entire southern coast of the Caspian Sea and finally runs nort ...
mountain range forms a barrier between the south Caspian and the Iranian plateau. This range is located in northern Iran, parallel to the southern margin of Caspian Sea
The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central Asia ...
. Alborz is characterized by the dominance of platform-type sediments, including limestone, dolomite, and clastic rocks. Rock units from Precambrian to Quaternary have been identified, with some hiatuses and unconformities in Paleozoic and Mesozoic. Unlike its northern and southern boundaries, (Caspian Sea and Central Iran, respectively) there is not a consensus regarding the eastern and the western limits of Alborz. The Binalud Mountains
The Binalud Mountain Range or the Binalud Range ( fa, بینالود - ''Bīnālūd'') is a mountain range that runs in a northwest-southeast direction between the Nishapur and Mashhad regions in Razavi Khorasan Province in northeastern Iran, ...
in the east, although the continuation of the Alborz, bear features comparable to those of Central Iran. The Alborz mountain range is only 60–130 km wide and consists of sedimentary series dating from Upper Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...
to Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
, prevalently Jurassic limestone over a granite
Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
core. Continental conditions regarding sedimentation are reflected by thick Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
s and by Jurassic shales containing coal
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal is formed when dea ...
seams. Marine conditions are reflected by Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
and Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
strata that are composed mainly of limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
s. In the Eastern Alborz Range, the far eastern section is formed by the Mesozoic
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 Cretaceo ...
(chiefly Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
and Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
) rocks, while the western part of the Eastern Alborz Range is made primarily of the Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ' ...
rocks. The 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 the ...
rocks can be found chiefly south of the city of Gorgan
Gorgan ( fa, گرگان ; also romanized as ''Gorgān'', ''Gurgān'', and ''Gurgan''), formerly Esterabad ( ; also romanized as ''Astarābād'', ''Asterabad'', and ''Esterābād''), is the capital city of Golestan Province, Iran. It lies appro ...
situated in the southeast of the Caspian Sea and in much smaller portions in the central and western parts of the Central Alborz Range. The central part of the Central Alborz Range is formed predominantly of the Triassic and Jurassic rocks, while the northwestern section of the range is made chiefly of Jurassic rocks. Very thick beds of the Tertiary (mostly of the Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
) green volcanic tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...
s and lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...
s are found mainly in the southwestern and south-central parts of the range. The far northwestern part of the Alborz that constitutes what is called the Western Alborz Range or the Talish Mountains
Talysh Mountains ( tly, Tolışə Bandon, script=Latn, fa, کوههای تالش, Kuhhâye Tâleš; az, Talış dağları) is a mountain range in far southeastern Azerbaijan and far northwestern Iran within Ardabil Province and Gilan Province ...
is made mainly of the Upper Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
volcano-sedimentary deposits with a strip of Paleozoic rocks and a band of Triassic and Jurassic rocks in the southern parts, both in a northwest-southeast direction. With the northward movement of Africa and the Arabian plate and with the closure of the Tethys Sea
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 ...
as the Arabian Plate collided with the Iranian Plate and was pushed against it, and with the clockwise movement of the Eurasian Plate towards the Iranian Plate and their final collision, the Iranian Plate was pressed from both sides. The collisions finally caused the folding of the Upper Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ' ...
, Mesozoic
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 Cretaceo ...
, and Paleogene
The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...
rocks, and 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 ...
(chiefly the Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
) volcanism
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...
to form the Alborz Mountains mainly in the Miocene. The Alpine orogeny began, therefore, with Eocene volcanism in southwestern and south-central parts of the Alborz and continued with the uplift and folding of the older sedimentary rocks in the northwestern, central and eastern parts of the range during the orogenic phases of importance that date from the Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
and the Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Azerbaijan
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 ...
. According to some authors, the northeastern corner could be included in Alborz and the southeastern part in Sanandaj–Sirjan. Some believe that most of Azerbaijan lies in a zone called Azerbaijan–Alborz, and as they indicate, this zone is bounded in the north by Alborz Fault, in the west by Tabriz–Urumiyeh Fault, and in the south by Semnan Fault. According to the some authors, the northern part of Azerbaijan continues to the Caucasus Mountains
The Caucasus Mountains,
: pronounced
* hy, Կովկասյան լեռներ,
: pronounced
* az, Qafqaz dağları, pronounced
* rus, Кавка́зские го́ры, Kavkázskiye góry, kɐfˈkasːkʲɪje ˈɡorɨ
* tr, Kafkas Dağla ...
in Caucasia and the Pontus Mountains in Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
and the Southern Azerbaijan is comparable with Central Iran and Western Iran and extends to the Taurus Mountains
The Taurus Mountains ( Turkish: ''Toros Dağları'' or ''Toroslar'') are a mountain complex in southern Turkey, separating the Mediterranean coastal region from the central Anatolian Plateau. The system extends along a curve from Lake Eğirdir ...
in Turkey. The significant structural event occurring in Early Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
was accompanied by faulting and fragmentation that led to a different sedimentary facies in Azerbaijan. This orogenic episode generated the Tabriz fault, extending in a northwest–southeast direction from Zanjan depression to the northern mountains of Tabriz (Mishu, Morou) and northwest of Azerbaijan and the Caucasus. This event divided Azerbaijan into two blocks, one block in the northeast with subsidence and sedimentation in Early Devonian and the other in the southwest which remained high until Late Carboniferous.
Stratigraphy of Iran
Precambrian
The consolidation of the Iranian basement bymetamorphism
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...
, partial granitization and partly by intense folding took place in the Late Precambrian. This event has been attributed to the 'Baikalian' or Pan–African orogeny by various authors. Isotopic data of Iranian basement rocks give ages between 600 and 900 Ma. A similar range of isotopic data had been obtained for Arabian Shield rocks. An important post-Pan-African magmatism
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of ...
is documented by the widespread Doran Granite, which cuts the Upper Precambrian rocks and is covered by Lower Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
sediments. Late Precambrian postorogenic volcanics, mainly alkali rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...
, rhyolite tuff and basic dikes are known in the Eocambrian formations. In North and Central Iran, Kahar
The Kahars are a community of palanquin bearers originating from the Gangatic region.
Kahars are present in most parts of India, but are concentrated in North India. They are found mainly in West Uttar Pradesh, in Sarsawa, Saharanpur, Farruk ...
and Gharehdash Formations and the lower half of the Soltanieh Formation are 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 the ...
age. The oldest rocks in Iran belong to the Kushk Series consisting of clastic sediments, acidic volcanic, tuff, and carbonates (mainly dolomite Dolomite may refer to:
*Dolomite (mineral), a carbonate mineral
*Dolomite (rock), also known as dolostone, a sedimentary carbonate rock
*Dolomite, Alabama, United States, an unincorporated community
*Dolomite, California, United States, an unincor ...
). Other formations of Late Precambrian–Early Cambrian ages include Rizu volcanic-sedimentary formation, Dezu and Tashk Formations, Aghda Limestone, Kalmard Series, Shorm Beds, and Anarak metamorphic units. The sedimentary facies of Precambrian–Lower Cambrian rocks in Northern Iran is different from that of Central Iran.
Paleozoic
With thePan-African orogeny
The Pan-African orogeny was a series of major Neoproterozoic orogenic events which related to the formation of the supercontinents Gondwana and Pannotia about 600 million years ago. This orogeny is also known as the Pan-Gondwanan or Saldanian Oro ...
and following this orogenic episode, shallow marine sediments formed in Late Vendian
The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and the ...
. The influence of the orogenic episode is evident at the base of the Vendian sediments. Deposition of shallow marine sediments covered large areas in Iran during Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ' ...
(e.g., Alborz, East of Iran, Zagros). There is strong stratigraphic evidence that transition from Vendian to Lower Cambrian was a progressive one, without hiatuses; there is no evidence for any orogenic or epeirogenic movements in Iran at this time (e.g., south of Zanjan, Valiabad Chalus, Shahin Dezh). Early Cambrian started with an alternation of shale, phosphate-bearing limestone, and dolomite sitting conformably and transitionally over Vendian dolomites. Transition from Soltanieh Formation to Barut, Zaigoon, and Laloon Formations is very difficult to recognize in the field. Middle Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
is characterized by uplift and regression; however, a renewed progression at this time led to the deposition of Mila and Kuhbonan Formations, consisting of limestone, dolomite, and shale, over older units. These formations bear trilobite
Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...
s and brachiopod
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...
s of Middle and Late Cambrian age. In some areas, the Late Cambrian carbonate facies turns transitionally into Ordovician graptolite
Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding
Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and ...
shales, known as the Lashkarak Formation in Alborz
The Alborz ( fa, البرز) range, also spelled as Alburz, Elburz or Elborz, is a mountain range in northern Iran that stretches from the border of Azerbaijan along the western and entire southern coast of the Caspian Sea and finally runs nort ...
, Shirgasht Formation in Central Iran and Ilbeyk and Zardkuh Formations in Zagros. In Kalmard area, Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...
sediments are sitting on the Vendian sediments through an angular unconformity. In the Late Ordovician, most parts of Iran were affected by epeirogenic movements; this coincides with Caledonian orogeny
The Caledonian orogeny was a mountain-building era recorded in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occ ...
in Europe and some other parts of the earth. The epeirogeny
In geology, epeirogenic movement (from Greek ''epeiros'', land, and ''genesis'', birth) is upheavals or depressions of land exhibiting long wavelengths and little folding apart from broad undulations.
The broad central parts of continents are ...
caused a distinct hiatus at the Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...
–Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
boundary. Where present, the Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
rocks in Iran consist mainly of limestone, sandstone, shale and volcanic materials, known as Niur Formation in Central Iran. The Lower Devonian rocks have been reported from several localities in Central Iran (e.g., Tabas, Sourian, Kerman
Kerman ( fa, كرمان, Kermân ; also romanization of Persian, romanized as Kermun and Karmana), known in ancient times as the satrapy of Carmania, is the capital city of Kerman Province, Iran. At the 2011 census, its population was 821,394, in ...
, Zagros); however, they seem to be missing in Alborz and parts of Zagros. Upper Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
is characterized by marine transgression, particularly in Alborz, that extends into Lower Carboniferous. With exception of Tabas
Tabas ( fa, طبس, also Romanized as Ṭabas), formerly known as Golshan, is the capital city of Tabas County in South Khorasan Province of Iran. At the 2011 census, its population was 35,150, in 9,903 families.
Tabas is located in central Iran, ...
area, no record of Middle Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
marine deposits has yet been discovered in Iran. Upper Carboniferous deposits are not significantly present in Iran and have only been identified in several localities from index goniatites. After a general regression and a distinct hiatus in Upper Carboniferous, Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
marine transgression deposits cover most parts of Iran (e.g., Alborz, Zagros, Central Iran); The Permian sediments are represented by Dorood Sandstones, Ruteh and Nesen Limestones in Alborz.
Mesozoic
The LowerTriassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
sediments in Iran are mainly of shallow marine or continental shelf nature (e.g., Doroud sandstones and Elika dolomite Dolomite may refer to:
*Dolomite (mineral), a carbonate mineral
*Dolomite (rock), also known as dolostone, a sedimentary carbonate rock
*Dolomite, Alabama, United States, an unincorporated community
*Dolomite, California, United States, an unincor ...
s in Alborz, Sorkh shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...
s and Shotori dolomites in Central Iran. A continuous Permian–Triassic sequence has been reported from several areas in Iran, including Jolfa (northwest of Iran), Abadeh (Southern Central Iran), and Southern Urumiyeh (the continuation of the Taurus in Turkey), north of Kandovan and Southern Amol
Amol ( fa, آمل – ; ; also Romanized as Āmol and Amul) is a city and the administrative center of Amol County, Mazandaran Province, Iran, with a population of around 300,000 people.
Amol is located on the Haraz river bank. It is less than ...
. Transition from Middle to Upper Triassic coincides with Early Cimmerian orogenic episode, which led to the segmentation of the sedimentary basin into three sub-basins: Zagros in the south and southwest, Alborz in the north, and Central Iran. The Lower Jurassic rocks conformably overlie the Upper Triassic units; so are the Early Cretaceous deposits over the Upper Jurassic strata (e.g., Zagros). In North and Central Iran, the Upper Triassic and Lower–Middle Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
sediments have a detrital nature, consisting mainly of shale and sandstone with thicknesses varying from a few meters to more than . The presence of plant remains and coal beds suggest a continental or lagoon environment for the deposits. The Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
deposits, characterized by diverse sedimentary facies, are widespread all over Iran. In Late Cretaceous, tectonic movements related to the Laramide orogeny
The Laramide orogeny was a time period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the o ...
affects most parts of Iran, leading to uplift, folding, and faulting. This is a prelude to significant developments in the geological evolution of Iran.
Cenozoic
In Iran theCenozoic
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 ...
begins with the Cretaceous–Paleocene boundary that is characterized by striking changes in sedimentary environments (e.g., Alborz, Central Iran). An unconformity has been reported from many locations in Iran. Both continuous and discontinuous transitions have been discovered between Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
and Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
strata; as is the case with Eocene and Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
(e.g., Central Iran). The Oligocene and Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
stages are characterized by rapid subsidence, deposition, and facies changes in both marine and continental sedimentary basins (e.g., Mahneshan and Halab south of Zanjan). Oligocene sediments in most parts of Iran are of shallow marine character, turning into marine facies in Upper Oligocene through Lower Miocene (e.g., Qom). The Middle to Upper Miocene sediments are mostly of continental nature. The Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
is the prominent feature of the plains of Iran.
Magmatism and igneous rocks
Magmatic rocks of all ages, from thePrecambrian
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 the ...
to the Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
, are widespread in Iran (e.g., Doran Granite
Doran may refer to:
People
* Abbas Doran (1950–1982d), Iranian IRIAF fighter pilot
* Ann Doran (1911–2000), American character actress
* Beauchamp Doran (1860–1943), British Army officer during the First World War
* Bill Doran (disambi ...
, Zarigan–Narigan Granite, Torghabeh Granite, Ghaen Granite, Chaghand Gabbro, Alvand Granite and Natanz Granite). A correlation exists between distribution of magmatic rocks and certain types of ore
Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...
deposits (e.g., iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
deposits in Bafq
Bafq ( fa, بافق, also Romanized as Bāfq) is a city in and the capital of Bafq County, Yazd Province, Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bo ...
related to Zarigan–Narigan-type granites, Mazraeh copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
deposits related to Sheyvar–Daghi Granite, Sarcheshmeh
Sarcheshmeh (سرچشمه) or Sarcheshmeh Copper Complex ( fa, كارخانجات مجتمع مس سرچشمه – ''Kārkhāneh-ye Mojtame‘-e Mes-e Sar Cheshmeh'') is a large open cast copper mine in the Kerman Province of Iran, conside ...
porphyry deposit related to Sarcheshmeh porphyry body). Several episodes of magmatic activity
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion o ...
have been identified in Iran. These episodes could be described as:
Upper Precambrian–Lower Cambrian
Volcanic andplutonic rock
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March ...
s with an age of 630–530 million years have been reported from many localities in Iran, particularly in Central Iran and Azerbaijan. These magmatic rocks seem to be related to the Pan-African tectonic-magmatic episode. Most magmatic rocks of this time bear an alkaline nature. The following magmatic series can be attributed to this phase: Doran-type intrusions in Azerbaijan. Narigan and Zarigan-type intrusive bodies extend from Anarak
Anarak ( fa, انارک, also Romanized as Anārak) is a city and capital of Anarak District, in Nain County, Isfahan Province, Iran. At the 2006 census, its population was 1,285, in 462 families. It is situated at an altitude of .
Anarak is l ...
to Bafq
Bafq ( fa, بافق, also Romanized as Bāfq) is a city in and the capital of Bafq County, Yazd Province, Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bo ...
and Kuhbonan. Volcanic rock
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic r ...
s, mostly of rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...
composition, in Ghareh Dash, Azerbaijan. Volcanic rocks associated with Kushk Series in the Bafq area. Volcanic rocks of Rizu, Dezu, and Kushk Formations in Central Iran. Most 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 the ...
metamorphic rock
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
s of greenschist
Greenschists are metamorphic rocks that formed under the lowest temperatures and pressures usually produced by regional metamorphism, typically and 2–10 kilobars (). Greenschists commonly have an abundance of green minerals such as chlorite ...
or even amphibolite
Amphibolite () is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky ...
facies, such as in Takab
Takab or Tekab ( fa, تكاب, az, تیکانتپه, ) is a city and capital of Takab County, West Azerbaijan Province, Iran. At the 2006 census, its population was 43,702, in 10,078 families.
The famous historical complex Takht-e Soleyman ...
and Anarak areas, seem to have originally been volcanic materials, either lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...
or pyroclastic rock
Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyrocl ...
s.
Lower Paleozoic
Magmatic rocks of this time have been reported from many areas in Iran. Examples include basaltic rocks ofShahrud
The Shahrud (Turkish ''Şehrud'' from Persian شاهرود, DMG ''šāh-i rūd'' or ''šāh-rūd'') was a short-necked lute, illustrated in the '' Surname-i Hümayun'', resembling an oud or barbat, but being much larger. The larger size gave t ...
and Khosh Yeilagh, andesitic-basaltic units of Niur Formation in Central Iran, and tuffaceous materials in the upper parts of Mila Formation in Eastern Iran.
Upper Paleozoic
Volcanic rocks of andesitic-basaltic composition accompany Upper Paleozoic sedimentary strata in many areas all over Iran. Basaltic rocks associated with Jeyrud Formation of Upper Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
are a typical example. There is strong evidence for significant magmatic activities in Late Paleozoic–Early Mesozoic (Early Permian to Early Jurassic) in Iran. Examples include: magmatic rocks in the Southern Sanandaj
Sanandaj (Persian: سنندج, ; ku, سنە, Sine, often romanized as Senneh, is the capital of Kurdistan Province in Iran. With a population of 414,069, Sanandaj is the twenty third largest city in Iran and the second largest Kurdish city. San ...
–Sirjan
Sirjan ( fa, سيرجان, also Romanized as Sīrjān; formerly Sa‘īdābād) is a city and the capital of Sirjan County, Kerman Province,in the south of Iran. According to the 2016 census, its population was 324,103 in 95,357 families. Sirjan ...
(granite
Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
s and gabbro
Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is che ...
s of Sirjan area) and volcanic rocks of Songhor Series in Northern Sanandaj–Sirjan. Ultramafic and mafic rocks and their metamorphosed equivalents could be observed in Eastern Iran (Fariman area), Taknar Series, Gorgan
Gorgan ( fa, گرگان ; also romanized as ''Gorgān'', ''Gurgān'', and ''Gurgan''), formerly Esterabad ( ; also romanized as ''Astarābād'', ''Asterabad'', and ''Esterābād''), is the capital city of Golestan Province, Iran. It lies appro ...
schists, and Shanderman mafic/ultramafic metamorphic series.
Mesozoic
TheMesozoic
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 Cretaceo ...
magmatic rocks are associated with Cimmerian
The Cimmerians (Akkadian: , romanized: ; Hebrew: , romanized: ; Ancient Greek: , romanized: ; Latin: ) were an ancient Eastern Iranian equestrian nomadic people originating in the Caspian steppe, part of whom subsequently migrated into West Asi ...
and Laramide
The Laramide orogeny was a time period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of th ...
orogenic events that caused continental and oceanic rifting, followed by closures and collisions in vast areas of Iran (e.g., Sanandaj–Sirjan). The Mesozoic magmatic rocks can be divided into three groups: Volcanic rock
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic r ...
s: These rocks occurred mainly as a result of extension or tension related to the continental rifting, or subduction of the developed oceanic lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time sca ...
under the continental lithosphere (e.g., Central Alborz for continental rifting; Saghez-Sanandaj axis for subduction). Intrusive rock
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form ''Igneous intrusion, intrusions'', such as batholiths, dike (geology), dikes, Sill (geology), sills, laccoliths, and volcanic necks.I ...
s: Many intrusive bodies of mafic to granitic composition, with ages varying from early Triassic to Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
, have been identified in Iran (e.g., Borujerd
Borujerd ( fa, بروجرد ''Borūjerd'') is a city and the capital of Borujerd County, Lorestan Province in western Iran. At the 2016 census, its population was 234,997 persons. Among the existing modern cities in Iran, Borujerd is one of the ...
–Shamsabad axis). In Triassic–Jurassic, volcanic rocks predominated the plutonic rock
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March ...
s. They are mainly alkaline in nature and are more abundant in Sanandaj–Sirjan. In Jurassic–Cretaceous, intrusive rocks exceed volcanic rocks; a significant number of batholith
A batholith () is a large mass of intrusive igneous rock (also called plutonic rock), larger than in area, that forms from cooled magma deep in Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such ...
s in Iran occurred at this time. Kolah Ghazi, Shir Kuh
Shir ( fa, شير, " Lion") may refer to:
* Shir, Mazandaran, a village in Fereydunkenar County, Iran
* Shir, South Khorasan, a village in Sarbisheh County, Iran
* Shir, Syria, a village
* Shir (Neolithic site), a site in western Syria, near Hama
...
, and Shah Kuh were formed by Jurassic granite; and Mount Alvand was made by Upper Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
-Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
granite.
Cenozoic
TheTertiary
Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago.
The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...
is of great concern in Iran because of the great volumes and highly diverse types of igneous rock
Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...
s and associated mineral deposits. Magmatic rock
Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or l ...
s of this age are widespread all over Iran, except in the Zagros
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 Zāgro ...
and Kopet Dagh
The Köpet Dag, Kopet Dagh, or Koppeh Dagh ( tk, Köpetdag; fa, کپهداغ), also known as the Turkmen-Khorasan Mountain Range, is a mountain range on the border between Turkmenistan and Iran that extends about along the border southeast o ...
. Data from various structural zones indicate that the volcanic and plutonic activities started in the Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
, peaked in the Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
, and continued, with short stops, into the Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
. Some of the more important regions in terms of the Tertiary magmatic activities include: Sahand
Sahand ( fa, سهند), is a massive, heavily eroded stratovolcano in East Azerbaijan Province, northwestern Iran. At , it is the highest mountain in the province of East Azarbaijan.
Sahand is one of the highest mountains in Iranian Azerbaijan, ...
-Bazman
Bazman ( fa, بزمان, also known as Kuh-e Bazman) is a dormant stratovolcano in a remote desert region of Sistan and Baluchestan Province in south-eastern Iran. A 500-m-wide crater caps the summit of the dominantly andesitic-dacitic volcano ...
(or Urumiyeh-Dokhtar) volcanic-plutonic belt with a series of famous mountain ranges including the Karkas Mountains
The Karkas mountain chain ( Persian رشته كوه كركس ''Reshteh kuh-e Karkas'') is a mountain range which is located almost in central Iran. Having a northwest-southeast direction, it is stretched from Kashan to Ardestan for more than 100 ...
and Jebal Barez
The Jebal Barez is a mountain chain in the Kerman Province of Iran. This mountain range stretches for some 100 km north-west to south-east, parallel to the Halil Rud, to the north-east of Jiroft and to the south-west of Bam, rising to a maxi ...
and important peaks such as Karkas, Marshenan, Hezar and Lalehzar. The Tertiary magmatism could also be observed in 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 ...
, Tarom– Taleghan, Central Alborz and its southern margins, Kavir–Sabzevar
Sabzevar ( fa, سبزوار ), previously known as Beyhagh (also spelled "Beihagh"; fa, بيهق), is a city and capital of Sabzevar County, in Razavi Khorasan Province, approximately west of the provincial capital Mashhad, in northeastern ...
, Kashmar
Kashmar () ( fa, کاشمر, also Romanized as ''Kāshmar''; formerly ''Keshmar'', '' Torshīz'' or ''Soltanabad'') is a city and the capital of Kashmar County, in Razavi Khorasan Province, Iran. Kashmar is located near the river Shesh Tara ...
–Torbat-e Jam
Torbat-e Jawm ( fa, تربت جام, Torbat-e Jām; also known as Torbat-e Sheykh Jām and Turbat-i-Shaikh Jam) is a city and capital of Torbat-e Jam County, in Razavi Khorasan Province, Iran. At the 2016 census, its population was 100,449. Torb ...
, Lut and Kavir, Central Iran, Sistan
Sistān ( fa, سیستان), known in ancient times as Sakastān ( fa, سَكاستان, "the land of the Saka"), is a historical and geographical region in present-day Eastern Iran ( Sistan and Baluchestan Province) and Southern Afghanistan (N ...
, Bam, Bazman, Taftan, East Iran, and Southern Jazmurian– Sabzevaran. The Quaternary volcanism
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...
produced very high peaks such as Sahand
Sahand ( fa, سهند), is a massive, heavily eroded stratovolcano in East Azerbaijan Province, northwestern Iran. At , it is the highest mountain in the province of East Azarbaijan.
Sahand is one of the highest mountains in Iranian Azerbaijan, ...
, Sabalan
Sabalan ( Persian: سبلان ) is an inactive stratovolcano in Ardabil Province of northwestern Iran.
At in elevation, it is the third-highest mountain in Iran. It has a permanent crater lake formed at its summit. On one of its slopes aroun ...
, Damavand
Mount Damavand ( fa, دماوند ) is a dormant stratovolcano, the highest peak in Iran and Western Asia and the highest volcano in Asia and the 2nd highest volcano in the Eastern Hemisphere (after Mount Kilimanjaro), at an elevation of . ...
, Taftan Taftan (in Persian: تفتان ''Taftân'') may refer to:
* Taftan (volcano), located in Sistan and Baluchestan province of Iran
* Taftan, Balochistan
Taftan ( ur, ) ( bal, ) is a trunk road and railway town in Chagai District, Balochistan, ...
, Bazman
Bazman ( fa, بزمان, also known as Kuh-e Bazman) is a dormant stratovolcano in a remote desert region of Sistan and Baluchestan Province in south-eastern Iran. A 500-m-wide crater caps the summit of the dominantly andesitic-dacitic volcano ...
and many others.
Ophiolite series and ultramafic rocks
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 i ...
series and ultramafic rock
Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed ...
s have a widespread occurrence in Iran and can be grouped as follows: Ultramafic and mafic units of Late Precambrian–Early Cambrian. Although comparable to modern ophiolites, these rocks do not display all typical features of an oceanic crust. The term “old ophiolite” might be a misnomer. These rocks are widespread in Takab
Takab or Tekab ( fa, تكاب, az, تیکانتپه, ) is a city and capital of Takab County, West Azerbaijan Province, Iran. At the 2006 census, its population was 43,702, in 10,078 families.
The famous historical complex Takht-e Soleyman ...
and Anarak
Anarak ( fa, انارک, also Romanized as Anārak) is a city and capital of Anarak District, in Nain County, Isfahan Province, Iran. At the 2006 census, its population was 1,285, in 462 families. It is situated at an altitude of .
Anarak is l ...
Regions. They might be representing a protorift. Ultramafic and mafic rock
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...
s of Upper Paleozoic occur as metamorphosed as well as non-metamorphosed bodies in some areas like Fariman
Fariman ( fa, فريمان; also Romanized as Farīmān; also known as Farīmūn) is a city and capital of Fariman County, Razavi Khorasan Province, Iran. At the 2006 census, its population was 32,610, in 8,203 families.
Notable people
* Khodadad ...
, Shanderman, and Asalem. These rocks display many typical features of modern ophiolites. Ophiolite series of Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
–Paleogene
The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...
age show typical features of ophiolitic sequences and are thought to be associated with the closure of the Neotethys
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
Earth is the third planet from the Sun and the only astronomical object known to ...
. These ophiolite series are widespread in Iran. Some of the more important locations include Kermanshah
Kermanshah ( fa, کرمانشاه, Kermânšâh ), also known as Kermashan (; romanized: Kirmaşan), is the capital of Kermanshah Province, located from Tehran in the western part of Iran. According to the 2016 census, its population is 946,68 ...
–Neyriz
Neyriz ( fa, نیریز, also Romanized as Neyrīz and Nīrīz) is the capital city of Neyriz County, Fars Province, Iran. At the 2016 census, its population was 113.291.
The name is also used for the district in which it is situated and fo ...
–Oman
Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of t ...
Belt, Makran
Makran ( fa, مكران), mentioned in some sources as Mecran and Mokrān, is the coastal region of Baluchistan. It is a semi-desert coastal strip in Balochistan, in Pakistan and Iran, along the coast of the Gulf of Oman. It extends westwards, ...
(south of Jazmurian), ultramafic–mafic rocks related to Flysch Zone in Khash
Khash may refer to:
*Khash (dish), South Caucasian dish
*Khash Rod District, a district in Nimruz Province, Afghanistan
**Khash, Nimruz, capital of Khash Rod District, Afghanistan
* Khash District, a district in Badakhshan Province, Afghanistan
*K ...
–Nosrat Abad–Birjand
Birjand ( fa, بیرجند , also Romanized as Bīrjand and Birdjand) is the capital of the Iranian province of South Khorasan. The city is known for its saffron, barberry, jujube, and handmade carpet exports.
Birjand had a population of 187,0 ...
Belt, ultramafic and mafic rocks north of Dorooneh fault, Torbat-e Jam
Torbat-e Jawm ( fa, تربت جام, Torbat-e Jām; also known as Torbat-e Sheykh Jām and Turbat-i-Shaikh Jam) is a city and capital of Torbat-e Jam County, in Razavi Khorasan Province, Iran. At the 2016 census, its population was 100,449. Torb ...
–Torbat-e Heydarieh
Torbat-e Heydarieh ( fa, تربت حيدريه, also Romanized as Torbat-e Ḩeydarīyeh; also known as Torbat-e Heydari, Turbat-i-Haidari, Torbate Heydari, and Turbet-i-Haidari, and for short Torbat) is a city and capital of Torbat-e Heydarieh C ...
–Sabzevar
Sabzevar ( fa, سبزوار ), previously known as Beyhagh (also spelled "Beihagh"; fa, بيهق), is a city and capital of Sabzevar County, in Razavi Khorasan Province, approximately west of the provincial capital Mashhad, in northeastern ...
–Fariman
Fariman ( fa, فريمان; also Romanized as Farīmān; also known as Farīmūn) is a city and capital of Fariman County, Razavi Khorasan Province, Iran. At the 2006 census, its population was 32,610, in 8,203 families.
Notable people
* Khodadad ...
regions, and Central Iran–Nain–Baft–Shahr-e Babak
Shahr-e Babak ( fa, شهربابك, also romanized as Shahr-e Bābak, Shahr-i-Bābak, and Shahr Bābak) is a city and capital of Shahr-e Babak County, Kerman Province, Iran. At the 2006 census, its population was 43,916, in 10,401 families.
Si ...
, Khoy
Khoy (Persian and az, خوی; ; ; also Romanized as Khoi), is a city and capital of Khoy County, West Azerbaijan Province, Iran. At the 2012 census, its population was 200,985.
Khoy is located north of the province's capital and largest city ...
– Maku. Ultramafic and mafic rocks also occur in association with large gabbroic intrusions. This type probably resulted from differentiation in a large mafic magma chamber, comparable to those of the layered mafic intrusions. Examples occur in Sero, Urumiyeh, and in Masooleh that are Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
to Lower Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
in age. The most remarkable occurrence of ophiolite could be observed in the Bashagard Mountains
The Bashagard Mountains or the Bashagerd Mountains (also known as Bashagird or Bashakerd) is a mountain range that is located in southeast of Iran. The mountain range runs in an arc almost in a northwest-southeast direction from eastern parts of H ...
in the southeast and the Jaghatai Mountains in the northeast of Iran.
Orogenic events in Iran
Pan-African
ThePan-African orogeny
The Pan-African orogeny was a series of major Neoproterozoic orogenic events which related to the formation of the supercontinents Gondwana and Pannotia about 600 million years ago. This orogeny is also known as the Pan-Gondwanan or Saldanian Oro ...
is equivalent to Asynitic in other parts of the earth. This event was associated with metamorphism
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...
, magmatism
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of ...
, folding, and faulting during Late Precambrian–Early Cambrian in Iran (e.g., south of Zanjan–Mahabad
Mahabad ( fa, مهاباد, ku, مەهاباد, translit=Mehabad), also Romanized as Mihābād and Muhābād and formerly known as Savojbolagh, is a city and capital of Mahabad County, West Azerbaijan Province, Iran. At the 2006 census, its ...
in 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 ...
, Bafq
Bafq ( fa, بافق, also Romanized as Bāfq) is a city in and the capital of Bafq County, Yazd Province, Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bo ...
in Central Iran. This tectonic phase started with tension or extension leading to the formation of rifts and generation of oceanic crust (e.g., in Takab and Anarak) and ended with folding, closure, metamorphism, growth of the continental crust, and development of regional faults.
Caledonian
There was no considerable folding or faulting related to this event in Iran. TheCaledonian orogeny
The Caledonian orogeny was a mountain-building era recorded in the northern parts of the British Isles, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occ ...
in Iran is characterized by facies change in sedimentary basins, hiatuses, and epeirogenic movements (e.g., parts of Alborz, Zagros, and Central Iran). This phase, starting from Late Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...
, caused the marine facies of Barut and Zaigoon Formations to change into the continental facies of Lalun Formation, and continued on to Late Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...
.
Hercynian
The effects of this orogenic episode in Iran can be traced from the Late Devonian. Due to the scarcity of magmatism, metamorphism, and folding related to this episode, the role of the Hercynian orogeny
The Variscan or Hercynian orogeny was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea.
Nomenclature
The name ''Variscan'', comes f ...
in Iran is controversial; the Hercynian in Iran is largely represented by extensional rather than compressional tectonics (e.g., Sanandaj–Sirjan). Iranian microplates east and northeast of the Zagros were detached from 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 stages ...
in the Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
during this orogenic phase.
The Neo-Tethys opening and rifting of Iran from the northern margin of Gondwana has probably occurred sometime between the latest Viséan
The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from to Ma. It follow ...
to early Late Carboniferous ( Bashkirian). Evidence for this conclusion are:
# the northern Paleo-Tethyan affinity of the foraminiferal associations in the late Viséan-late Sepukhovian in Alborz
# the unique similarity between the Bashkirian-Kasimovian
The Kasimovian is a geochronology, geochronologic age (geology), age or chronostratigraphy, chronostratigraphic stage (stratigraphy), stage in the International Commission on Stratigraphy, ICS geologic timescale. It is the third stage in the Penn ...
and late Gzhelian
The Gzhelian ( ) is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from to Ma. It follows the Kasim ...
fusulinid assemblages of Iran to the northern margin of the Paleo-Tethys
# the Carboniferous magmatic activities in northwestern Iran and normal faulting and tilted blocks in the High Zagros Belt which, taken together, support extensional deformation related to the Variscan or Hercynian orogeny.Arefifard, 2017, p.143
Early Cimmerian
The Early Cimmerian orogeny is one of the most important tectonic events in the geological history of the earth. Many diverse features are associated with this phase, includingmetamorphism
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...
, magmatism
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of ...
, folding, faulting, creation of new basins, and facies change. This event was associated with compressional tectonics
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...
in the northern Iran and tensional tectonics in the south. There is evidence that the compressional phase was preceded by tension and rift development. The compressional phase, happening in the Late Triassic
The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...
, finally led to the closure of the Paleotethys
The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; exi ...
(e.g., southeast to southwest of Caspian Sea
The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central Asia ...
). Iranian microplates that had been detached from 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 stages ...
in the Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
and that had been submerged and had moved northwards toward 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 Pan ...
finally collided with the Eurasia
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...
n section of the northern supercontinent Laurasia in the Late Triassic.
Late Cimmerian
The Late Cimmerian orogeny occurred as a significant tectonic event in Iran in Late Jurassic–Early Cretaceous times. This event is represented by folding, facies changes in sedimentary environments, angular unconformity, magmatism, and metamorphism (e.g., Alborz, Sanandaj–Sirjan, and Central Iran). TheJurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
granite
Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
of Kolah Ghazi, Shir Kuh, and Shah Kuh was made during this orogenic phase.
Laramide
TheLaramide orogeny
The Laramide orogeny was a time period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the o ...
happened in the Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
–Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
and played a great role in the geological evolution of Iran. This event started under a compressional regime, followed by an extensional one. The compressional regime, that was associated with significant intrusive magmatic activities, led to the closure of the oceanic basins and Neothetyan rifts. In some areas, slices of the oceanic crust have obducted onto the continental margins producing what could be called ophiolite assemblages or coloured melanges (e.g., mostly seen suture zone between Sanandaj–Sirjan and Zagros, and alongside Nehbandan fault in the east of Iran). The Upper Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
-Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
granite of Mount Alvand was formed during the Laramide orogeny.
Alpine (Pyrenean and Styrian)
With regards to the geological evidence, this event was of compressional nature. This tectonic phase is represented by significant changes in the sedimentary environments,plutonism
Plutonism is the geologic theory that the igneous rocks forming the Earth originated from intrusive magmatic activity, with a continuing gradual process of weathering and erosion wearing away rocks, which were then deposited on the sea bed, re- ...
, and metamorphism
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...
(e.g., west of Central Iran, south of Central Alborz, Lut). The Sahand
Sahand ( fa, سهند), is a massive, heavily eroded stratovolcano in East Azerbaijan Province, northwestern Iran. At , it is the highest mountain in the province of East Azarbaijan.
Sahand is one of the highest mountains in Iranian Azerbaijan, ...
-Bazman
Bazman ( fa, بزمان, also known as Kuh-e Bazman) is a dormant stratovolcano in a remote desert region of Sistan and Baluchestan Province in south-eastern Iran. A 500-m-wide crater caps the summit of the dominantly andesitic-dacitic volcano ...
volcanic arc or belt was mainly formed during the Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
volcanism
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...
of the Alpine orogeny. The northern movement and the final collision of Afro-Arabia (significantly the Arabian Plate) with the Iranian Plate
The Iranian Plate is a small tectonic plate thought to underlie the Persian plateau, covering the modern-day countries of Iran and Afghanistan, and parts of Iraq and Pakistan. It is compressed between the Arabian Plate to the southwest, the E ...
and the clockwise rotation 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 ...
towards the Iranian Plate caused the Alpine orogeny with the Pyrenean phase in the Late Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
- Early Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
and the Styrian phase in the Middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene.
The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...
respectively. The Zagros
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 Zāgro ...
, Alborz
The Alborz ( fa, البرز) range, also spelled as Alburz, Elburz or Elborz, is a mountain range in northern Iran that stretches from the border of Azerbaijan along the western and entire southern coast of the Caspian Sea and finally runs nort ...
, and Kopet-Dagh
The Köpet Dag, Kopet Dagh, or Koppeh Dagh ( tk, Köpetdag; fa, کپهداغ), also known as the Turkmen-Khorasan Mountain Range, is a mountain range on the border between Turkmenistan and Iran that extends about along the border southeast o ...
mountains were mainly formed in the Miocene during this orogenic phase.
Pasadenian
This orogenic phase began in theLate Pliocene
Late may refer to:
* LATE, an acronym which could stand for:
** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia
** Local-authority trading enterprise, a New Zealand business law
** Local average treatment effect, ...
and continued in the Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
. The Pasadenian orogeny is the most important phase in forging the current shape of Iran. Some younger orogenic events might be the continuation of this orogenic phase (e.g., Alborz–Azerbaijan axis, Zagros, Central Iran). Sahand
Sahand ( fa, سهند), is a massive, heavily eroded stratovolcano in East Azerbaijan Province, northwestern Iran. At , it is the highest mountain in the province of East Azarbaijan.
Sahand is one of the highest mountains in Iranian Azerbaijan, ...
, Sabalan
Sabalan ( Persian: سبلان ) is an inactive stratovolcano in Ardabil Province of northwestern Iran.
At in elevation, it is the third-highest mountain in Iran. It has a permanent crater lake formed at its summit. On one of its slopes aroun ...
, Damavand
Mount Damavand ( fa, دماوند ) is a dormant stratovolcano, the highest peak in Iran and Western Asia and the highest volcano in Asia and the 2nd highest volcano in the Eastern Hemisphere (after Mount Kilimanjaro), at an elevation of . ...
, Bazman
Bazman ( fa, بزمان, also known as Kuh-e Bazman) is a dormant stratovolcano in a remote desert region of Sistan and Baluchestan Province in south-eastern Iran. A 500-m-wide crater caps the summit of the dominantly andesitic-dacitic volcano ...
and Taftan Taftan (in Persian: تفتان ''Taftân'') may refer to:
* Taftan (volcano), located in Sistan and Baluchestan province of Iran
* Taftan, Balochistan
Taftan ( ur, ) ( bal, ) is a trunk road and railway town in Chagai District, Balochistan, ...
were mainly formed during the volcanism
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...
of this orogenic phase.Geological Map of Iran, National Geoscience Database of Iran, www.ngdir.ir With an elevation of , Mount Damavand
Mount Damavand ( fa, دماوند ) is a dormant stratovolcano, the highest peak in Iran and Western Asia and the highest volcano in Asia and the 2nd highest volcano in the Eastern Hemisphere (after Mount Kilimanjaro), at an elevation of ...
is the highest peak in Iran. This volcano first erupted in the Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
about 1.78 million years ago and after several known eruptions around 600,000 and 280,000 years ago, it finally erupted in the Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
almost 7300 years ago.
See also
*National Geoscience Database of Iran
The National Geoscience Database of Iran or in brief NGDIR is a scientific and research government agency in Iran which works in the field of Geology of Iran and centrally manages Geoscience data. This center was established in 1999 in the field ...
* National Geographical Organization of Iran
The National Geographical Organization of Iran or National Geographical Organization of the Armed Forces of Iran ( fa, سازمان جغرافیایی ایران, or fa, سازمان جغرافیایی نیروهای مسلح) is an Iran, Irania ...
References
Bibliography
* Material was copied from this source, which is available under Creative Commons Attribution 4.0 International License
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