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80-591: Zikirti or Zikirtu , (also: Zikirta , Zikurti , Zekertu ) was an ancient kingdom (750-521 BC), in the north of the Zagros Mountains , which comprised the easternmost part of Greater Mannaea . Geographically it corresponds with the modern counties of Takab and Shahin Dezh in northwestern Iran . This Middle Eastern history –related article is a stub . You can help Misplaced Pages by expanding it . Zagros Mountains The Zagros Mountains are

160-513: A Lur tribe from Iran , primarily inhabiting the Central and South Zagros. Major cities inhabited by Bakhtiaris include Masjed Soleyman , Izeh and Shahr-e Kord . A significant number of Bakhtiari still practice nomadic pastoralism. Kurds are another Iranic group found in the northwestern and the eastern Zagros Taurus mountain ranges , which spans southeastern Turkey, northwestern Iran, northern Iraq, and northern Syria. The high altitude of

240-400: A (usually small) angle. Sometimes multiple sets of layers with different orientations exist in the same rock, a structure called cross-bedding . Cross-bedding is characteristic of deposition by a flowing medium (wind or water). The opposite of cross-bedding is parallel lamination, where all sedimentary layering is parallel. Differences in laminations are generally caused by cyclic changes in

320-674: A common feature of the Zagros Mountains. Salt domes are an important target for petroleum exploration , as the impermeable salt frequently traps petroleum beneath other rock layers. There is also much water-soluble gypsum in the region. The mountains are completely of sedimentary origin and are made primarily of limestone . In the Elevated Zagros or the Higher Zagros, the Paleozoic rocks can be found mainly in

400-424: A diagenetic structure common in carbonate rocks is a stylolite . Stylolites are irregular planes where material was dissolved into the pore fluids in the rock. This can result in the precipitation of a certain chemical species producing colouring and staining of the rock, or the formation of concretions . Concretions are roughly concentric bodies with a different composition from the host rock. Their formation can be

480-567: A layer of rock salt (acting as a ductile decollement with a low basal friction ), whereas in the NW Zagros the salt layer is missing or is very thin. This different basal friction is partly responsible for the different topographies on either side of the Kazerun fault. Higher topography and narrower zone of deformation in the NW Zagros is observed whereas in the SE, deformation was spread more and

560-510: A long mountain range in Iran , northern Iraq , and southeastern Turkey . The mountain range has a total length of 1,600 km (990 miles). The Zagros range begins in northwestern Iran and roughly follows Iran's western border while covering much of southeastern Turkey and northeastern Iraq. From this border region, the range continues southeast to the waters of the Persian Gulf . It spans

640-463: A particular sedimentary environment. Examples of bed forms include dunes and ripple marks . Sole markings, such as tool marks and flute casts, are grooves eroded on a surface that are preserved by renewed sedimentation. These are often elongated structures and can be used to establish the direction of the flow during deposition. Ripple marks also form in flowing water. There can be symmetric or asymmetric. Asymmetric ripples form in environments where

720-465: A red colour does not necessarily mean the rock formed in a continental environment or arid climate. The presence of organic material can colour a rock black or grey. Organic material is formed from dead organisms, mostly plants. Normally, such material eventually decays by oxidation or bacterial activity. Under anoxic circumstances, however, organic material cannot decay and leaves a dark sediment, rich in organic material. This can, for example, occur at

800-489: A rock is usually expressed with the Wentworth scale, though alternative scales are sometimes used. The grain size can be expressed as a diameter or a volume, and is always an average value, since a rock is composed of clasts with different sizes. The statistical distribution of grain sizes is different for different rock types and is described in a property called the sorting of the rock. When all clasts are more or less of

880-465: A sediment after its initial deposition. This includes compaction and lithification of the sediments. Early stages of diagenesis, described as eogenesis , take place at shallow depths (a few tens of meters) and is characterized by bioturbation and mineralogical changes in the sediments, with only slight compaction. The red hematite that gives red bed sandstones their color is likely formed during eogenesis. Some biochemical processes, like

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960-431: A sedimentary rock may have been present in the original sediments or may formed by precipitation during diagenesis. In the second case, a mineral precipitate may have grown over an older generation of cement. A complex diagenetic history can be established by optical mineralogy , using a petrographic microscope . Carbonate rocks predominantly consist of carbonate minerals such as calcite, aragonite or dolomite . Both

1040-516: A small-scale property of a rock, but determines many of its large-scale properties, such as the density , porosity or permeability . The 3D orientation of the clasts is called the fabric of the rock. The size and form of clasts can be used to determine the velocity and direction of current in the sedimentary environment that moved the clasts from their origin; fine, calcareous mud only settles in quiet water while gravel and larger clasts are moved only by rapidly moving water. The grain size of

1120-952: A term for a fissile mudrock (regardless of grain size) although some older literature uses the term "shale" as a synonym for mudrock. Biochemical sedimentary rocks are created when organisms use materials dissolved in air or water to build their tissue. Examples include: Chemical sedimentary rock forms when mineral constituents in solution become supersaturated and inorganically precipitate . Common chemical sedimentary rocks include oolitic limestone and rocks composed of evaporite minerals, such as halite (rock salt), sylvite , baryte and gypsum . This fourth miscellaneous category includes volcanic tuff and volcanic breccias formed by deposition and later cementation of lava fragments erupted by volcanoes, and impact breccias formed after impact events . Alternatively, sedimentary rocks can be subdivided into compositional groups based on their mineralogy: Sedimentary rocks are formed when sediment

1200-417: A texture, only the average size of the crystals and the fabric are necessary. Most sedimentary rocks contain either quartz ( siliciclastic rocks) or calcite ( carbonate rocks ). In contrast to igneous and metamorphic rocks, a sedimentary rock usually contains very few different major minerals. However, the origin of the minerals in a sedimentary rock is often more complex than in an igneous rock. Minerals in

1280-425: A valuable indicator of the biological and ecological environment that existed after the sediment was deposited. On the other hand, the burrowing activity of organisms can destroy other (primary) structures in the sediment, making a reconstruction more difficult. Secondary structures can also form by diagenesis or the formation of a soil ( pedogenesis ) when a sediment is exposed above the water level. An example of

1360-471: A 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 rocks . Subsequent erosion removed softer rocks, such as mudstone (rock formed by consolidated mud) and siltstone (a slightly coarser-grained mudstone) while leaving harder rocks, such as limestone (calcium-rich rock consisting of

1440-503: Is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension . This sediment is often formed when weathering and erosion break down a rock into loose material in a source area. The material is then transported from the source area to the deposition area. The type of sediment transported depends on the geology of the hinterland (the source area of the sediment). However, some sedimentary rocks, such as evaporites , are composed of material that form at

1520-421: Is a structure where beds with a smaller grain size occur on top of beds with larger grains. This structure forms when fast flowing water stops flowing. Larger, heavier clasts in suspension settle first, then smaller clasts. Although graded bedding can form in many different environments, it is a characteristic of turbidity currents . The surface of a particular bed, called the bedform , can also be indicative of

1600-701: Is also home to populations of Assyrians , Turkic peoples and Farsi speaking Iranians . The mountains contain several ecosystems . Prominent among them are the forest and forest steppe areas with a semi-arid climate . As defined by the World Wildlife Fund and used in their Wildfinder, the particular terrestrial ecoregion of the mid to high mountain area is Zagros Mountains forest steppe (PA0446). The annual precipitation ranges from 400–800 mm (16–31 in) and falls mostly in winter and spring. Winters are severe, with low temperatures often below −25 °C (−13 °F). The region exemplifies

1680-409: Is called bedding . Single beds can be a couple of centimetres to several meters thick. Finer, less pronounced layers are called laminae, and the structure a lamina forms in a rock is called lamination . Laminae are usually less than a few centimetres thick. Though bedding and lamination are often originally horizontal in nature, this is not always the case. In some environments, beds are deposited at

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1760-429: Is higher when the sedimentation rate is high (so that a carcass is quickly buried), in anoxic environments (where little bacterial activity occurs) or when the organism had a particularly hard skeleton. Larger, well-preserved fossils are relatively rare. Fossils can be both the direct remains or imprints of organisms and their skeletons. Most commonly preserved are the harder parts of organisms such as bones, shells, and

1840-491: Is mirrored by the broad categories of rudites , arenites , and lutites , respectively, in older literature. The subdivision of these three broad categories is based on differences in clast shape (conglomerates and breccias), composition (sandstones), or grain size or texture (mudrocks). Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel. Sandstone classification schemes vary widely, but most geologists have adopted

1920-401: Is reduced. Sediments are typically saturated with groundwater or seawater when originally deposited, and as pore space is reduced, much of these connate fluids are expelled. In addition to this physical compaction, chemical compaction may take place via pressure solution . Points of contact between grains are under the greatest strain, and the strained mineral is more soluble than the rest of

2000-493: Is the most stable, followed by feldspar , micas , and finally other less stable minerals that are only present when little weathering has occurred. The amount of weathering depends mainly on the distance to the source area, the local climate and the time it took for the sediment to be transported to the point where it is deposited. In most sedimentary rocks, mica, feldspar and less stable minerals have been weathered to clay minerals like kaolinite , illite or smectite . Among

2080-620: The Earth's crust is extensive (73% of the Earth's current land surface), but sedimentary rock is estimated to be only 8% of the volume of the crust. Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks . Sedimentary rocks are deposited in layers as strata , forming a structure called bedding . Sedimentary rocks are often deposited in large structures called sedimentary basins . Sedimentary rocks have also been found on Mars . The study of sedimentary rocks and rock strata provides information about

2160-819: The Fars Province have somewhat lower summits, reaching 4,000 metres (13,000 feet). They contain some limestone rocks showing abundant marine fossils. The peaks that are at least 3800 meters high and have a topographic prominence of at least 300 meters: The Zagros Mountains have significant ancient history. They were occupied by early humans since the Lower Paleolithic Period. The earliest human fossils discovered in Zagros belongs to Neanderthals and come from Shanidar Cave , Bisitun Cave , and Wezmeh Cave. The remains of ten Neanderthals , dating from around 65,000–35,000 years ago, have been found in

2240-722: The Miocene (about 25–5 mya or million years ago ) and folded the entirety of the rocks that had been deposited from the Paleozoic (541–242 mya) to the Cenozoic (66 mya – present) in the passive continental margin on the Arabian Plate. However, the obduction of Neotethys oceanic crust during the Cretaceous (145–66 mya), and the continental arc collision in the Eocene (56–34 mya) both had major effects on uplifts in

2320-562: The Neolithic period . The DNA from this bone fragment shows that it is from a distinct genetic group, which was not known to scientists before. He belongs to the Y-DNA haplogroup G2b, specifically its branch G-Y37100 , and mitochondrial haplogroup J1d6. He had brown eyes, relatively dark skin, and black hair, although Neolithic pre Indo-European Iranians carried reduced pigmentation-associated alleles in several genes and derived alleles at 7 of

2400-689: The Paleogene (66–23 mya) rocks south of the Cretaceous rocks and then the Neogene (23–2.6 mya) rocks south of the Paleogene rocks. The mountains are divided into many parallel sub-ranges (up to 10 or 250 km (6.2 or 155.3 miles) wide), and orogenically have the same age as the Alps . Iran's main oilfields lie in the western central foothills of the Zagros mountain range. The southern ranges of

2480-643: The Sumerian , Akkadian and Assyrian cities of Mesopotamia . The mountains create a geographic barrier between the Mesopotamian Plain, which is in modern Iraq , and the Iranian plateau . A small archive of clay tablets detailing the complex interactions of these groups in the early second millennium BC has been found at Tell Shemshara along the Little Zab . Tell Bazmusian , near Shemshara,

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2560-519: The Zagros Mountains mouse-like hamster ( Calomyscus bailwardi ), the Basra reed-warbler ( Acrocephalus griseldis ) and the striped hyena ( Hyena hyena ). The Persian fallow deer ( Dama dama mesopotamica ), an ancient domesticate once thought extinct, was rediscovered in the late 20th century in Khuzestan Province, in the southern Zagros. Also, wild goats can be found almost all over

2640-412: The history of life . The scientific discipline that studies the properties and origin of sedimentary rocks is called sedimentology . Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences , such as pedology , geomorphology , geochemistry and structural geology . Sedimentary rocks can be subdivided into four groups based on

2720-682: The organic material of a dead organism undergoes chemical reactions in which volatiles such as water and carbon dioxide are expulsed. The fossil, in the end, consists of a thin layer of pure carbon or its mineralized form, graphite . This form of fossilisation is called carbonisation . It is particularly important for plant fossils. The same process is responsible for the formation of fossil fuels like lignite or coal. Structures in sedimentary rocks can be divided into primary structures (formed during deposition) and secondary structures (formed after deposition). Unlike textures, structures are always large-scale features that can easily be studied in

2800-500: The pet trade and habitat destruction . Climate change is predicted to strongly impact this species. The entrance to the ancient Mesopotamian underworld was believed to be located in the Zagros Mountains in the far east. A staircase led down to the gates of the underworld. The underworld itself is usually located even deeper below ground than the Abzu , the body of freshwater which the ancient Mesopotamians believed lay deep beneath

2880-550: The 12 loci, showing the strongest signatures of selection in ancient Eurasians. He did not contribute to the genetic makeup of early European farmers or modern Europeans . Instead, he was the most genetically similar to modern Iranian Zoroastrians , followed by Fars , Balochi , Brahui , Kalash and Georgians . Gallego-Llorente et al. (2016) believes that the Zagros Mountain was a plausible source of Eurasian ancestry in Central and South Asia, along with Kotias , which

2960-501: The Dott scheme, which uses the relative abundance of quartz, feldspar, and lithic framework grains and the abundance of a muddy matrix between the larger grains. Six sandstone names are possible using the descriptors for grain composition (quartz-, feldspathic-, and lithic-) and the amount of matrix (wacke or arenite). For example, a quartz arenite would be composed of mostly (>90%) quartz grains and have little or no clayey matrix between

3040-650: The Last Glacial Period they had been glaciated to a depth in excess of 1,900 metres (1.2 miles), and during the Last Glacial Period to a depth in excess of 2,160 metres (7,090 feet). Evidence exists of a 20 km (12 miles) wide glacier fed along a 17 km (11 miles) long valley dropping approximately 1,600 m (5,200 ft) along its length on the north side of Kuh-i-Jupar with a thickness of 350–550 m (1,150–1,800 ft). Under conditions of precipitation comparable to current climatic record-keeping, this size of glacier could be expected to form where

3120-652: The Shanidar Cave. The cave also contains two later " proto-Neolithic " cemeteries, one of which dates back about 10,600 years and contains 35 individuals. Evidence from later Upper Paleolithic and Epipaleolithic occupations come from Yafteh Cave, Kaldar Cave near Khoramabad , and Warwasi , Malaverd near Kermanshah , Kenacheh Cave in Kurdistan, Boof Cave in Fars and a number of other caves and rock shelters. Signs of early agriculture date back as far as 9000 BC in

3200-463: The Zagros into two distinct zones of deformation. The GPS results also show different shortening directions along the belt, normal shortening in the southeast, and oblique shortening in the northwest Zagros. The Zagros mountains were created around the time of the second ice age, which caused the tectonic collision, leading to its uniqueness. The sedimentary cover in the SE Zagros is deforming above

3280-545: The Zagros mountain range. In the late 19th century, the Asiatic lion ( Panthera leo persica ) inhabited the southwestern part of the mountains. It is now extinct in this region. The Luristan newt ( Neurergus kaiseri ) is a salamander endemic to a small section of the central Zagros Mountains in Iran. It lives in highland streams and is primarily aquatic. This newt is considered vulnerable to extinction due to poaching for

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3360-530: The Zagros mountains produces a series of choke points and valleys perfect for agriculture and human development. It has also long defended the Kurds in times of war by acting as a natural barrier . Qashqai people are a tribal confederation in Iran mostly of Turkic origin. Significant populations can be found in Central and South Zagros, especially around the city of Shiraz in the Fars province . The Zagros

3440-470: The activity of bacteria , can affect minerals in a rock and are therefore seen as part of diagenesis. Deeper burial is accompanied by mesogenesis , during which most of the compaction and lithification takes place. Compaction takes place as the sediments come under increasing overburden (lithostatic) pressure from overlying sediments. Sediment grains move into more compact arrangements, grains of ductile minerals (such as mica ) are deformed, and pore space

3520-454: The annual average temperature was between 10.5 and 11.2 °C (50.9 and 52.2 °F), but since conditions are expected to have been dryer during the period in which this glacier was formed, the temperature must have been lower. Although currently degraded through overgrazing and deforestation , the Zagros region is home to a rich and complex flora. Remnants of the originally widespread oak -dominated woodland can still be found, as can

3600-399: The bottom of deep seas and lakes. There is little water mixing in such environments; as a result, oxygen from surface water is not brought down, and the deposited sediment is normally a fine dark clay. Dark rocks, rich in organic material, are therefore often shales. The size , form and orientation of clasts (the original pieces of rock) in a sediment is called its texture . The texture is

3680-504: The cement and the clasts (including fossils and ooids ) of a carbonate sedimentary rock usually consist of carbonate minerals. The mineralogy of a clastic rock is determined by the material supplied by the source area, the manner of its transport to the place of deposition and the stability of that particular mineral. The resistance of rock-forming minerals to weathering is expressed by the Goldich dissolution series . In this series, quartz

3760-421: The cement to produce secondary porosity . At sufficiently high temperature and pressure, the realm of diagenesis makes way for metamorphism , the process that forms metamorphic rock . The color of a sedimentary rock is often mostly determined by iron , an element with two major oxides: iron(II) oxide and iron(III) oxide . Iron(II) oxide (FeO) only forms under low oxygen ( anoxic ) circumstances and gives

3840-615: The continental variation of the Mediterranean climate pattern, with a snowy winter and mild, rainy spring, followed by a dry summer and autumn. The mountains of the East-Zagros, the Kuh-i-Jupar (4,135 m (13,566 ft)), Kuh-i-Lalezar (4,374 m (14,350 ft)) and Kuh-i-Hezar (4,469 m (14,662 ft)) do not currently have glaciers. Only at Zard Kuh and Dena some glaciers still survive. However, before

3920-572: The current is in one direction, such as rivers. The longer flank of such ripples is on the upstream side of the current. Symmetric wave ripples occur in environments where currents reverse directions, such as tidal flats. Mudcracks are a bed form caused by the dehydration of sediment that occasionally comes above the water surface. Such structures are commonly found at tidal flats or point bars along rivers. Secondary sedimentary structures are those which formed after deposition. Such structures form by chemical, physical and biological processes within

4000-663: The dominant particle size. Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions: gravel (>2 mm diameter), sand (1/16 to 2 mm diameter), and mud (<1/16 mm diameter). Mud is further divided into silt (1/16 to 1/256 mm diameter) and clay (<1/256 mm diameter). The classification of clastic sedimentary rocks parallels this scheme; conglomerates and breccias are made mostly of gravel, sandstones are made mostly of sand , and mudrocks are made mostly of mud. This tripartite subdivision

4080-453: The earth. The region was influenced by Mesopotamian and Hurrian religion in the Bronze and Iron Ages, and later by Zoroastrianism and Syriac Christianity . Today the vast majority of the population are Iranic and Turkic Muslims , with small numbers of Christians , mainly Assyrians and Armenians also extant. Sedimentary rock The sedimentary rock cover of the continents of

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4160-489: The field. Sedimentary structures can indicate something about the sedimentary environment or can serve to tell which side originally faced up where tectonics have tilted or overturned sedimentary layers. Sedimentary rocks are laid down in layers called beds or strata . A bed is defined as a layer of rock that has a uniform lithology and texture. Beds form by the deposition of layers of sediment on top of each other. The sequence of beds that characterizes sedimentary rocks

4240-404: The flow calms and the particles settle out of suspension . Most authors presently use the term "mudrock" to refer to all rocks composed dominantly of mud. Mudrocks can be divided into siltstones, composed dominantly of silt-sized particles; mudstones with subequal mixture of silt- and clay-sized particles; and claystones, composed mostly of clay-sized particles. Most authors use " shale " as

4320-506: The foothills of the Zagros mountains, including Sulaymaniyah , Kermanshah , Khorramabad , and Shiraz . The Lurs are an Iranic tribe, primarily inhabiting the Central, Western, and Southern Zagros. Cities inhibited by Lurs include Khorramabad , Borujerd , Malayer , Izeh , Shahr-e Kord , Yasuj . Lurs speak Luri and span across many provinces in Iran including Lorestan , Khuzestan , Chaharmahal and Bakthiari , Ilam , Kohgiluyeh and Boyer-Ahmad , and Hamedan . The Bakhtiaris are

4400-515: The foothills of the mountains. Some settlements later grew into cities, eventually named Anshan and Susa ; Jarmo is one archaeological site in this area. Some of the earliest evidence of wine production has been discovered in the mountains; both the settlements of Hajji Firuz Tepe and Godin Tepe have given evidence of wine storage dating between 3500 and 5400 BC. A human metatarsal bone fragment from Wezmeh Cave has been analyzed and dated to

4480-485: The grain. As a result, the contact points are dissolved away, allowing the grains to come into closer contact. The increased pressure and temperature stimulate further chemical reactions, such as the reactions by which organic material becomes lignite or coal. Lithification follows closely on compaction, as increased temperatures at depth hasten the precipitation of cement that binds the grains together. Pressure solution contributes to this process of cementation , as

4560-510: The grains, a lithic wacke would have abundant lithic grains and abundant muddy matrix, etc. Although the Dott classification scheme is widely used by sedimentologists, common names like greywacke , arkose , and quartz sandstone are still widely used by non-specialists and in popular literature. Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles. These relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as

4640-587: The host rock. For example, a shell consisting of calcite can dissolve while a cement of silica then fills the cavity. In the same way, precipitating minerals can fill cavities formerly occupied by blood vessels , vascular tissue or other soft tissues. This preserves the form of the organism but changes the chemical composition, a process called permineralization . The most common minerals involved in permineralization are various forms of amorphous silica ( chalcedony , flint , chert ), carbonates (especially calcite), and pyrite . At high pressure and temperature,

4720-435: The lithologies dehydrates. Clay can be easily compressed as a result of dehydration, while sand retains the same volume and becomes relatively less dense. On the other hand, when the pore fluid pressure in a sand layer surpasses a critical point, the sand can break through overlying clay layers and flow through, forming discordant bodies of sedimentary rock called sedimentary dykes . The same process can form mud volcanoes on

4800-480: The major mountain belts like Alborz and Zagros. A relatively dense GPS network which covered the Iranian Zagros also proves a high rate of deformation within the Zagros. The GPS results show that the current rate of shortening in the southeast Zagros is ~10 mm/a (0.39 in/year), dropping to ~5 mm/a (0.20 in/year) in the northwest Zagros. The north–south Kazerun strike-slip fault divides

4880-450: The mineral dissolved from strained contact points is redeposited in the unstrained pore spaces. This further reduces porosity and makes the rock more compact and competent . Unroofing of buried sedimentary rock is accompanied by telogenesis , the third and final stage of diagenesis. As erosion reduces the depth of burial, renewed exposure to meteoric water produces additional changes to the sedimentary rock, such as leaching of some of

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4960-448: The mountain range include: Allium iranicum , Astragalus crenophila , Bellevalia kurdistanica , Cousinia carduchorum , Cousinia odontolepis , Echinops rectangularis , Erysimum boissieri , Iris barnumiae , Ornithogalum iraqense , Scrophularia atroglandulosa , Scorzonera kurdistanica , Tragopogon rechingeri , and Tulipa kurdica . The Zagros are home to many threatened and endangered species, including

5040-477: The northeastern parts of the belt. The process of collision continues to the present, and as the Arabian Plate is being pushed against the Eurasian Plate, the Zagros Mountains and the Iranian plateau are getting higher and higher. Recent GPS measurements in Iran have shown that this collision is still active and the resulting deformation is distributed non-uniformly in the country, mainly taken up in

5120-416: The park-like pistachio / almond steppelands. The ancestors of many familiar foods, including wheat, barley , lentil , almond, walnut , pistachio, apricot , plum , pomegranate and grape can be found growing wild throughout the mountains. Quercus brantii (covering more than 50% of the Zagros forest area) is the most important tree species of the Zagros in Iran. Other floral endemics found within

5200-438: The place of deposition. The nature of a sedimentary rock, therefore, not only depends on the sediment supply, but also on the sedimentary depositional environment in which it formed. As sediments accumulate in a depositional environment, older sediments are buried by younger sediments, and they undergo diagenesis. Diagenesis includes all the chemical, physical, and biological changes, exclusive of surface weathering, undergone by

5280-627: The processes responsible for their formation: clastic sedimentary rocks, biochemical (biogenic) sedimentary rocks, chemical sedimentary rocks, and a fourth category for "other" sedimentary rocks formed by impacts, volcanism , and other minor processes. Clastic sedimentary rocks are composed of rock fragments ( clasts ) that have been cemented together. The clasts are commonly individual grains of quartz , feldspar , clay minerals , or mica . However, any type of mineral may be present. Clasts may also be lithic fragments composed of more than one mineral. Clastic sedimentary rocks are subdivided according to

5360-418: The remains of marine organisms) and dolomite (rocks similar to limestone containing calcium and magnesium ). This differential erosion formed the linear ridges of the Zagros Mountains. The depositional environment and tectonic history of the rocks were conducive to the formation and trapping of petroleum, and the Zagros region is an important area for oil production. Salt domes and salt glaciers are

5440-480: The result of localized precipitation due to small differences in composition or porosity of the host rock, such as around fossils, inside burrows or around plant roots. In carbonate rocks such as limestone or chalk , chert or flint concretions are common, while terrestrial sandstones sometimes contain iron concretions. Calcite concretions in clay containing angular cavities or cracks are called septarian concretions . After deposition, physical processes can deform

5520-454: The rock a grey or greenish colour. Iron(III) oxide (Fe 2 O 3 ) in a richer oxygen environment is often found in the form of the mineral hematite and gives the rock a reddish to brownish colour. In arid continental climates rocks are in direct contact with the atmosphere, and oxidation is an important process, giving the rock a red or orange colour. Thick sequences of red sedimentary rocks formed in arid climates are called red beds . However,

5600-469: The same size, the rock is called 'well-sorted', and when there is a large spread in grain size, the rock is called 'poorly sorted'. The form of the clasts can reflect the origin of the rock. For example, coquina , a rock composed of clasts of broken shells, can only form in energetic water. The form of a clast can be described by using four parameters: Chemical sedimentary rocks have a non-clastic texture, consisting entirely of crystals. To describe such

5680-433: The sediment supply, caused, for example, by seasonal changes in rainfall, temperature or biochemical activity. Laminae that represent seasonal changes (similar to tree rings ) are called varves . Any sedimentary rock composed of millimeter or finer scale layers can be named with the general term laminite . When sedimentary rocks have no lamination at all, their structural character is called massive bedding. Graded bedding

5760-402: The sediment, producing a third class of secondary structures. Density contrasts between different sedimentary layers, such as between sand and clay, can result in flame structures or load casts , formed by inverted diapirism . While the clastic bed is still fluid, diapirism can cause a denser upper layer to sink into a lower layer. Sometimes, density contrasts occur or are enhanced when one of

5840-443: The sediment. They can be indicators of circumstances after deposition. Some can be used as way up criteria . Organic materials in a sediment can leave more traces than just fossils. Preserved tracks and burrows are examples of trace fossils (also called ichnofossils). Such traces are relatively rare. Most trace fossils are burrows of molluscs or arthropods . This burrowing is called bioturbation by sedimentologists. It can be

5920-638: The southern parts of the Armenian highlands , and the whole length of the western and southwestern Iranian plateau , ending at the Strait of Hormuz . The highest point is Mount Dena , at 4,409 metres (14,465 ft). The Zagros fold and thrust belt was mainly formed by the collision of two tectonic plates , the Eurasian Plate and the Arabian Plate . This collision mainly happened during

6000-453: The subsurface that is useful for civil engineering , for example in the construction of roads , houses , tunnels , canals or other structures. Sedimentary rocks are also important sources of natural resources including coal , fossil fuels , drinking water and ores . The study of the sequence of sedimentary rock strata is the main source for an understanding of the Earth's history , including palaeogeography , paleoclimatology and

6080-527: The three major types of rock, fossils are most commonly found in sedimentary rock. Unlike most igneous and metamorphic rocks, sedimentary rocks form at temperatures and pressures that do not destroy fossil remnants. Often these fossils may only be visible under magnification . Dead organisms in nature are usually quickly removed by scavengers , bacteria , rotting and erosion, but under exceptional circumstances, these natural processes are unable to take place, leading to fossilisation. The chance of fossilisation

6160-438: The upper and higher sections of the peaks of the Zagros Mountains, along the Zagros main fault. On both sides of this fault, there are Mesozoic rocks, a combination of Triassic (252–201 mya) and Jurassic (201–145 mya) rocks that are surrounded by Cretaceous rocks on 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 rocks, with

6240-404: The woody tissue of plants. Soft tissue has a much smaller chance of being fossilized, and the preservation of soft tissue of animals older than 40 million years is very rare. Imprints of organisms made while they were still alive are called trace fossils , examples of which are burrows , footprints , etc. As a part of a sedimentary rock, fossils undergo the same diagenetic processes as does

6320-530: Was inhabited by Caucasus Hunter-Gatherers. He cites archaeological evidence of eastward Neolithic expansions from the Near East. During early ancient times, the Zagros was the home of various Pre Indo-European peoples such as the Hurrians , Guti , Kassites , Elamites , Turukku and Lullubi , (together with Semitic peoples such as Assyrians and Amorites on the western side) who periodically invaded

6400-410: Was occupied between 5000 BCE and 800 CE, although not continuously. The Zagros mountains have been inhabited by different groups of pastoralists and farmers for thousands of years. Current Pastoralist groups such as Lurs , Bakhtiari Lurs , Kurds or Qashqais move from their herds from the east slopes in summer ( Yeylāgh ) to the west slopes in winter ( Gheshlāgh ). Some major cities are located on

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