The
Zagros Mountains ' onMouseout='HidePop("40137")' href="http://www.absoluteastronomy.com/topics/Assyrian_language">Assyrian
Assyrian language may refer to:*The Assyrian language, an extinct Semitic language spoken in ancient Assyria*the modern Assyrian Neo-Aramaic language...
: ܛܘܪ ܙܪܓܣ,
KurdishKurdish is the language spoken by Kurds in western Asia. Unlike many other languages it does not have a single standardized linguistic entity with the status of an official or state language...
: زنجیرهچیاکانی زاگرۆس, Lurish: کو یه لی زاگروس,
ArabicArabic is a Central Semitic language, thus related to and classified alongside other Semitic languages such as Hebrew and the Neo-Aramaic languages. In terms of speakers, the Arabic macrolanguage is the largest member of the Semitic language family. It is spoken by more than 280 million people as...
: زاجروس الجبال) are the largest
mountain rangeA mountain range is a chain of mountains bordered by highlands or separated from other mountains by passes or valleys. Individual mountains within the same mountain range do not necessarily have the same geology, though they often do; they may be a mix of different orogeny, for example volcanoes,...
in
IranIran , officially the Islamic Republic of Iran is a country in Western Asia. The name Iran has been in use natively since the Sassanid period and came into international use from 1935, before which the country was known internationally as Persia...
and
IraqIraq , officially the Republic of Iraq , also known as Mesopotamia, is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert.Iraq shares borders with Jordan to the west, Syria...
. With a total length of 1,500 km (932 mi), from northwestern Iran, and roughly correlating with Iran's western border, the Zagros range spans the whole length of the western and southwestern
Iranian plateauThe Iranian plateau, also known as the Persian plateau is a geological formation in Southwest Asia and Southern Asia. It is the part of the Eurasian Plate wedged between the Arabian and Indian plates, situated between the Zagros mountains to the west, the Caspian Sea and the Kopet Dag to the north,...
and ends at the Straits of Hormuz. The highest points in the Zagros Mountains are
Zard KuhZard Kuh, Zardkuh or Zard-e Kuh-e Bakhtiari is located in the central Zagros range of Khuzestan, Iran....
(4,548m) and Mt.
DenaDena is a mountain range within the Zagros Mountains of West/Southwestern Iran.Dena is a part of the Zagros mountain range, situated on the boundary of the Isfahan, Kohkilooyeh Va Boyer Ahmad, and Chahar Mahal Va Bakhtiyari provinces...
(4,359m). The
HazaranHazaran is the name of a massif of the Central Iranian Plateau, Kerman province, Iran, an eastern outlier of the Zagros mountains. The Jebal Barez chain is a continuation to the south-east....
massif in the
Kerman provinceKermān is one of the 30 provinces of Iran. It is in the south-east of Iran. Its' center is Kerman. The province of Kerman is the second largest province in Iran, 180,726 km². The population of the province is about 2.65 million...
forms an eastern outlier of the range, the
Jebal BarezThe Jebal Barez are a mountain chain in the Kerman Province of Iran.They stretch 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 maximal elevation of 3,400 m....
reaching into
SistanSīstān is a border region in eastern Iran and southwestern Afghanistan . Sistan derives its name from 'Sakastan', which Sistan was once the westernmost part of. The Sakas that were once native to Sistan were driven to the Punjab during the Arsacid era...
.
Etymology
The name
Zagros is derived from the
Zagarthians/SagarthiansThe Sagartians were an ancient Iranian tribe, dwelling in the Iranian plateau. Their exact location is unknown; they were probably neighbors of the Parthians in northeastern Iran...
—a Kurdish people who once inhabited the mountains, from the shores of
Lake VanLake Van is the largest lake in Turkey, located in the far east of the country in Van district. It is a saline and soda lake, receiving water from numerous small streams that descend from the surrounding mountains. Lake Van is one of the world's largest endorheic lakes...
to the coasts of
MakranMakran is a semi-desert coastal strip in the south of Balochistan, in Iran and Pakistan, along the coast of the Arabian Sea and the Gulf of Oman...
. Other explanations deriving the name from Greek
Zagreus, meaning stormy, or the name Za-G'R' meaning 'great mountain' in the
Avestan languageAvestan is an Eastern Iranian language known only from its use as the language of Zoroastrian scripture, i.e. the Avesta, from which it derives its name. The language must also at some time have been a natural language, but how long ago that was is unknown...
, are invalid. It is also said that before Greeks, it was called "اوپاریگی سهنه" which means "The Mountain With Iron on Its Top".
Geology
The Zagros Mountains (or
Fold-Thrust BeltA Fold and thrust belt is a series of mountainous foothills, adjacent to an orogenic belt, that form due to compression. Fold-thrust belts commonly form in the forelands adjacent to major orogens as deformation propagates outwards...
) were formed by collision of two tectonic plates — the
EurasianThe Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
and
Arabian PlateThe Arabian Plate is one of three tectonic plates which have been moving northward over millions of years toward an inevitable collision with Eurasia...
s. Recent GPS measurements in
IranIran , officially the Islamic Republic of Iran is a country in Western Asia. The name Iran has been in use natively since the Sassanid period and came into international use from 1935, before which the country was known internationally as Persia...
have shown that this collision is still active and the resulting deformation is distributed non-uniformly in the country, mainly taken up in the major mountain belts like
AlborzAlborz , also written as Alburz or Elburz, is a mountain range in northern Iran stretching from the borders of Armenia in the northwest to the southern end of the Caspian Sea, and ending in the east at the borders of Turkmenistan and Afghanistan...
and Zagros. A relatively dense GPS network which covered the Zagros in the Iranian part also proves a high rate of deformation within the Zagros. The GPS results show that the current rate of shortening in SE Zagros is ~10 mm/yr and ~5mm/yr in the NW Zagros. The NS strike-slip
KazerunKāzerūn is a city in Fars province, Iran, situated between Shiraz and Bushehr. It had an estimated population of 89,013 in 2005.Its agricultural products include date palms, citrus orchards, wheat, tobacco, rice, cotton, and vines....
fault divides the Zagros into two distinct zones of deformation. The GPS results also show different shortening directions along the belt, i.e. normal shortening in the South-East and oblique shortening in the NW Zagros.
The sedimentary cover in the SE Zagros is deforming above a layer of rock salt (acting as a ductile
decollementA décollement horizon in tectonics is a surface that acts as a gliding plane between two masses in a thrust fault relationship. A décollement horizon can either form due to a low bulk modulus between bodies , or can form along planes of high pore pressures....
with a low basal
frictionFriction is the force resisting the relative lateral motion of solid surfaces, fluid layers, or material elements in contact. It is usually subdivided into several varieties:...
) whereas in the NW Zagros the salt layer is missing or is very thin. This different basal friction partly made different topographies in either sides of Kazerun fault. Higher topography and narrower zone of deformation in the NW Zagros is observed whereas in the SE, deoformation was spreaded more and wider zone of deformation with lower topography was formed. Stresses induced in the Earth's crust by the collision caused extensive folding of the preexisting layered
sedimentary rockSedimentary rock is the type of rock that is formed by sedimentation of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
s. Subsequent erosion removed softer rocks, such as
mudstoneMudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
(rock formed by consolidated mud) and
siltstoneSiltstone is a sedimentary rock which has a composition intermediate in grain size between the coarser sandstones and the finer mudstones and shales.- Description :...
(a slightly coarser-grained mudstone) while leaving harder rocks, such as
limestoneLimestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geologic record...
(calcium-rich rock consisting of the remains of marine organisms) and
dolomiteDolomite is the name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate CaMg
2 found in crystals....
(rocks similar to limestone containing
calciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the Earth's crust...
and
magnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12 and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the earth's crust by mass, although ninth in the Universe as a whole...
). This differential
erosionErosion is a gravity driven process that moves solids in the natural environment or their source and deposits them elsewhere...
formed the linear ridges of the Zagros Mountains.
The
depositional environmentIn geology, sedimentary depositional environment describes the combination of physical, chemical and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock...
and tectonic history of the rocks were conducive to the formation and trapping of
petroleumPetroleum or crude oil is a naturally occurring, flammable liquid found in rock formations in the Earth consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds.The term "petroleum" was first used in the treatise De Natura Fossilium, published in...
, and the Zagros region is an important part of Persian Gulf oil production.
Salt domeA salt dome is a type of structural dome formed when a thick bed of evaporite minerals found at depth intrudes vertically into surrounding rock strata, forming a diapir....
s and
salt glacierA salt glacier is a flow of salt that is created when a rising diapir in a salt dome breaches the surface, much like toothpaste from a tube. Gravity causes the salt to flow like glaciers into adjacent valleys. Most of the flow occurs during the winter, when the salt is wet, as the strength of salt...
s are a common feature of the Zagros Mountains. Salt domes are an important target for oil exploration, as the impermeable salt frequently traps petroleum beneath other rock layers.
Type and age of rock
The mountains are divided into many parallel sub-ranges (up to 10, or 250 km wide), and have the same age as the
AlpsThe Alps are one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east; through Italy, Switzerland, Liechtenstein and Germany; to France in the west....
. Iran's main oilfields lie in the western central foothills of the Zagros mountain range. The southern ranges of the
Fars ProvinceFārs Fārs Fārs (pronounced /fɑː(ɹ)s/ (Persian: Fārs, Pārs) (Originally Pars) is one of the 30 provinces of Iran. It is in the south of the country and its center is Shiraz. It has an area of 122,400 km²...
have somewhat lower summits, reaching 4000 metres. They contain some limestone rocks showing abundant marine
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
s.
The Kuhrud Mountains form one of the parallel ranges at a distance of approx. 300 km to the east. The area between these two impressive mountain chains is home to a dense human population that lives in the intermediate valleys which are quite high in altitude with a temperate climate. Their rivers, which eventually reach
salt lakeA salt lake or saline lake is a landlocked body of water which has a concentration of salts and other minerals significantly higher than most lakes...
s, create fertile environments for agriculture and commerce.
Zagros in history
Signs of early agriculture date back as far as 9000 BCE to the foothills of the Zagros Mountains, in cities later named Anshan and
SusaSusa ; Syriac: ; was an ancient city of the Elamite, Persian and Parthian empires of Iran, located about 250 km east of the Tigris River....
.
JarmoJarmo is an archeological site located in Northern Iraq on the foothills of Zagros Mountains east of Kirkuk city . It is known as the oldest agricultural community in the world, dating back to 7000 BC...
is one archaeological site in this area.
ShanidarThe cave site of Shanidar is located in the Zagros Mountains of Kurdistan in Iraq. It was excavated between 1957-1961 by Ralph Solecki and his team from Columbia University and yielded the first adult Neanderthal skeletons in Iraq, dating between 60-80,000 years BP.The excavated area produced nine...
, where the ancient skeletal remains of
NeanderthalThe Neanderthal , or ), also spelled Neandertal, is an extinct member of the Homo genus that is known from Pleistocene specimens found in Europe and parts of western and central Asia. Neanderthals are either classified as a subspecies of humans or as a separate species...
s have been found, is another.
Some of the earliest evidence of production has been discovered in the Zagros Mountains; both the settlements of
Hajji Firuz TepeHajii Firuz Tepe was a Neolithic complex located in the northern Zagros Mountains of modern day Iran where some of the oldest archaeological evidence, in the form of pottery residue, of grape-based wine was discovered.-External links:...
and
Godin TepeGodin Tepe is a prehistoric settlement in western Iran, situated in the valley of Kangavar. Discovered in 1961, the site was excavated from 1965 and during the 1970s by an American expedition headed by T. Cuyler Young Jr. and sponsored by the Royal Ontario Museum...
have given evidence of wine storage dating between 3500 and 5400 BC.
During early ancient times, the Zagros was the home of peoples such as the
KassitesThe Kassites were an ancient Near Eastern tribe who gained control of Babylonia after the fall of the Old Babylonian Empire after ca. 1531 BC to ca. 1155 BC . Their language is classified as an isolate.-History:...
,
GutiGuti may refer to:*Guti Hernández, usually known as Guti, Spanish footballer*The Gutian people, founders of the Gutian dynasty of Sumer*A people of Scandia mentioned by Ptolemy ; in later Latin known as Gutones and Gothi....
,
AssyriansAssyrians or Assyrian people may refer to:*Ancient Assyrians*The modern Assyrian people language: ABOUT 750 BC, assyrians spoke two languages throughout history, ancient Assyrian,and Modern Assyrian....
, Elamites and
MitanniMitanni or Hanigalbat was a loosely organized Hurrian-speaking state in northern Syria from ca. 1500 BC-1300 BC...
, who periodically invaded the
SumerSumer was a civilization and historical region in southern Iraq . It is the earliest known civilization in the world and is known as the Cradle of Civilization...
ian and/or
AkkadThe Akkadian Empire was an empire centered in the city of Akkad and its surrounding region in Ancient Iraq ....
ian cities of
MesopotamiaMesopotamia "land between the rivers" is a name for the Tigris–Euphrates region in the eastern Mediterranean, largely corresponding to Iraq, as well as northeastern Syria, some parts of southeastern Turkey, and some parts of the Khūzestān Province of southwestern...
. The mountains create a geographic barrier between the flatlands of Mesopotamia which is in Iraq and the Iranian plateau.
External links