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The Zagros Mountains ((ペルシア語:رشته كوه زاگرس), (クルド語:زنجیرهچیاکانی زاگرۆس); ''Çiyayên Zagrosê'', Lurish: کو یه لی زاگروس, (アラビア語:جبال زغروس ) Aramaic: ܛܘܪ ܙܪܓܣ,) form the largest mountain range in Iran, Iraq and Eastern Turkey. This mountain range has a total length of 1,500 km (932 mi). The Zagros mountain range begins in northwestern Iran and roughly corresponds to Iran's western border, and it spans the whole length of the western and southwestern Iranian plateau, ending at the Strait of Hormuz. The highest point in the Zagros Mountains is Dena. These mountains are regarded as sacred by the Kurds. ==Geology== The Zagros fold and thrust belt was formed by collision of two tectonic plates — the Iranian Plate and the Arabian Plate. 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 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 are getting higher and higher. Recent GPS measurements in Iran〔Nilforoushan F., Masson F., Vernant P., Vigny C. , Martinod J. , Abbassi M.,Nankali H., Hatzfeld D., Bayer R., Tavakoli F., Ashtiani A.,Doerflinger E. , Daignières M., Collard P., Chéry J., 2003. GPS network monitors the Arabia-Eurasia collision deformation in Iran, Journal of Geodesy, 77, 411–422.〕 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 Alborz and Zagros. A relatively dense GPS network which covered the Zagros in the Iranian part〔Hessami K., Nilforoushan F., Talbot CJ., 2006, Active deformation within the Zagros Mountains deduced from GPS measurements, Journal of the Geological Society, London, 163, 143–148.〕 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 Kazerun 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 decollement with a low basal friction) 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, deformation was spread more and wider zone of deformation with lower topography was formed.〔Nilforoushan F , Koyi HA., Swantesson J.O.H., Talbot CJ., 2008, Effect of basal friction on surface and volumetric strain in models of convergent settings measured by laser scanner, Journal of Structural Geology, 30, 366–379.〕 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 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 part of Persian Gulf oil production. Salt domes and salt glaciers 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Zagros Mountains」の詳細全文を読む スポンサード リンク
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