@article{OmraniMoazzenOberhaensli2018,
  author    = {Omrani, Hadi and Moazzen, Mohssen and Oberh{\"a}nsli, Roland},
  title     = {Geodynamic evolution of the Sabzevar zone, northern central Iranian micro-continent},
  series = {Mineralogy and petrology},
  volume    = {112},
  journal   = {Mineralogy and petrology},
  number    = {1},
  publisher = {Springer},
  address   = {Wien},
  issn      = {0930-0708},
  doi       = {10.1007/s00710-017-0505-3},
  pages     = {65 -- 83},
  year      = {2018},
  abstract  = {The Northern Central Iranian Micro-continent (CIM) represents Neotethys-related oceanic crust remnants, emplaced due to convergence between CIM and Eurasia plates during Eocene. Mafic and ultramafic units are exposed along the northern part of the CIM in the Sabzevar area. The geology and field relation of Sabzevar ophiolite indicate northward subduction of the Sabzevar basin. The average whole rock chemistry of mafic (gabbros) and ultramafic samples (lherzolite, harzburgite and dunite) is characterized by a range of MgO of 11.16-31.88, CaO 5.22-11.53 and Al2O3 2.77-14.57, respectively. Low LREE/HREE ratio of ultramafic samples is accompanied by enrichment of large ion lithophile elements (LILE) such as Sr, Pb and K. Mafic samples show two distinct groups with low and high LREE/HREE ratios. The spider diagram of mafic samples indicates enrichment in Sr, Pb and K and depletion in REE. Petrological and geochemical evidence and field relations show that the mafic rocks formed in a supra-subduction zone setting. Petrological studies reveal the role of fractional crystallization and assimilation effect by released fluids during subduction related generation of the Sabzevar mafic rocks. We suggest that the studied mafic rocks likely represent the basement of an initial island arc, which was generated in a supra-subduction zone setting within the Neotethys branch of the Sabzevar Ocean at the north of CIM. Copper, gold and chromite mineralizations are studied in relation to island arc setting and supra-subduction environment. Similarities in lithology, ophiolite age and mineralization between Sabzevar ophiolite and Bardaskan-Torbat Heydariyeh ophiolites testify for their separation due to rotation (or faulting) of the Central Iranian Micro-continent.},
  language  = {en}
}
@article{OmraniMoazzenOberhaenslietal.2017,
  author    = {Omrani, Hadi and Moazzen, Mohssen and Oberh{\"a}nsli, Roland and Moslempour, Mohammad Elyas},
  title     = {Iranshahr blueschist: subduction of the inner Makran oceanic crust},
  series = {Journal of metamorphic geology},
  volume    = {35},
  journal   = {Journal of metamorphic geology},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0263-4929},
  doi       = {10.1111/jmg.12236},
  pages     = {373 -- 392},
  year      = {2017},
  abstract  = {The Makran accretionary prism in SE Iran and SW Pakistan is one of the most extensive subduction accretions on Earth. It is characterized by intense folding, thrust faulting and dislocation of the Cenozoic units that consist of sedimentary, igneous and metamorphic rocks. Rock units forming the northern Makran ophiolites are amalgamated as a melange. Metamorphic rocks, including greenschist, amphibolite and blueschist, resulted from metamorphism of mafic rocks and serpentinites. In spite of the geodynamic significance of blueschist in this area, it has been rarely studied. Peak metamorphic phases of the northern Makran mafic blueschist in the Iranshahr area are glaucophane, phengite, quartz +/- omphacite+epidote. Post peak minerals are chlorite, albite and calcic amphibole. Blueschist facies metasedimentary rocks contain garnet, phengite, albite and epidote in the matrix and as inclusions in glaucophane. The calculated P-T pseudosection for a representative metabasic glaucophane schist yields peak pressure and temperature of 11.5-15kbar at 400-510 degrees C. These rocks experienced retrograde metamorphism from blueschist to greenschist facies (350-450 degrees C and 7-8kbar) during exhumation. A back arc basin was formed due to northward subduction of Neotethys under Eurasia (Lut block). Exhumation of the high-pressure metamorphic rocks in northern Makran occurred contemporarily with subduction. Several reverse faults played an important role in exhumation of the ophiolitic and HP-LT rocks. The presence of serpentinite shows the possible role of a serpentinite diapir for exhumation of the blueschist. A tectonic model is proposed here for metamorphism and exhumation of oceanic crust and accretionary sedimentary rocks of the Makran area. Vast accretion of subducted materials caused southward migration of the shore.},
  language  = {en}
}
@article{OmraniMoazzenOberhaenslietal.2013,
  author    = {Omrani, Hadi and Moazzen, Mohssen and Oberh{\"a}nsli, Roland and Altenberger, Uwe and Lange, Manuela},
  title     = {The Sabzevar blueschists of the North-Central Iranian micro-continent as remnants of the Neotethys-related oceanic crust subduction},
  series = {International journal of earth sciences},
  volume    = {102},
  journal   = {International journal of earth sciences},
  number    = {5},
  publisher = {Springer},
  address   = {New York},
  issn      = {1437-3254},
  doi       = {10.1007/s00531-013-0881-9},
  pages     = {1491 -- 1512},
  year      = {2013},
  abstract  = {The Sabzevar ophiolites mark the Neotethys suture in east-north-central Iran. The Sabzevar metamorphic rocks, as part of the Cretaceous Sabzevar ophiolitic complex, consist of blueschist, amphibolite and greenschist. The Sabzevar blueschists contain sodic amphibole, epidote, phengite, calcite +/- A omphacite +/- A quartz. The epidote amphibolite is composed of sodic-calcic amphibole, epidote, albite, phengite, quartz +/- A omphacite, ilmenite and titanite. The greenschist contains chlorite, plagioclase and pyrite, as main minerals. Thermobarometry of a blueschist yields a pressure of 13-15.5 kbar at temperatures of 420-500 A degrees C. Peak metamorphic temperature/depth ratios were low (similar to 12 A degrees C/km), consistent with metamorphism in a subduction zone. The presence of epidote in the blueschist shows that the rocks were metamorphosed entirely within the epidote stability field. Amphibole schist samples experienced pressures of 5-7 kbar and temperatures between 450 and 550 A degrees C. The presence of chlorite, actinolite, biotite and titanite indicate greenschist facies metamorphism. Chlorite, albite and biotite replacing garnet or glaucophane suggests temperatures of > 300 A degrees C for greenschist facies. The formation of high-pressure metamorphic rocks is related to north-east-dipping subduction of the Neotethys oceanic crust and subsequent closure during lower Eocene between the Central Iranian Micro-continent and Eurasia (North Iran).},
  language  = {en}
}