فهرس المقالات hornfels

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  1 - Paragenesis and geochornological studies of Asnawa Iron Ore by the isotope and mineral chemistry in Penjween Area, Zagros Suture Zone Kurdistan Region, NE Iraq
  Kamal H. Karim Nabaz R.H. Aziz Al-Bidary Mayssa A.A.A
  The Asinawa iron ore is located about 3km to the southeast of Penjween town, Sulaimaniya Governorate, Kurdistan Region, Northeastern Iraq near the Iraq-Iran border. The exposed iron ore deposit is about 60 and 400m wide and long respectively. The present study is the re أکثر

  The Asinawa iron ore is located about 3km to the southeast of Penjween town, Sulaimaniya Governorate, Kurdistan Region, Northeastern Iraq near the Iraq-Iran border. The exposed iron ore deposit is about 60 and 400m wide and long respectively. The present study is the re-study of the geology and geochemistry of the Asnawan Iron ore deposit and concluded that the country rocks are consist of hornfels in which the original lamination or banding of the parent rocks (calc-silicate low grade metamorphic rocks) are preserved and inherited from its laminated sedimentary precursors. Moreover, the facies that is associated with host rocks is hornblende-hornfels facies with temperature range of 550-650 oC. This range is confirmed through thermo barometry. There are evidences of localized pyroxene-hornfels and sanidine hornfels facies too. Additionally, the detail of the different stages of the iron ore paragenesis is shown by discussion with the aid of suitable graphical drawing and geochemical variation diagrams. By these methods, the sedimentary stratigraphic unit of the parent rock (protolith) was found for the first time which consists of Qulqula Radiolarian Formation (Kermanshah Radiolarites in Iran). The bedded chert, limestone and calcareous shale is the main lithology of the latter formation and after burial and deformation, it is regionally metamorphosed to banded and lamiated calc-silicate rocks of green facies rocks. At a later stage, these rocks, remetamorphosed (polymetamorphism pattern) again to hornfels with concurrent changing to iron ore by basic iron rich hydrothermal solutions during Eocene (37-40Ma). This age is calculated using Ar39/Ar40 method of dating. تفاصيل المقالة
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  2 - A new view on the metamorphic rocks of the Boroujerd area
  Ahmad Ahmadi-Khalaji Zahra Tahmasbi Shahriar Keshtgar
  The studied area is as a small portion of Sanandaj - Sirjan Zone (SSZ). Metamorphic rocks in this area subdivided to 2 groups on their setting: Regional and Contact. Slate and Phyllite are petrographic facieses of regional metamorphism. This metamorphism has affected a أکثر

  The studied area is as a small portion of Sanandaj - Sirjan Zone (SSZ). Metamorphic rocks in this area subdivided to 2 groups on their setting: Regional and Contact. Slate and Phyllite are petrographic facieses of regional metamorphism. This metamorphism has affected a vast area and is of low grad in green schist (Chlorite Zone). The Boroujerd granitoid massif is elongated and parallels the prevailing schistose in these rocks by the trend of NW-SE. By the injection of it, a contact metamorphism has occurred which can be considered as a pyroxene hornfels facies. Contact metamorphic rocks, consisting of spotted schists, hornfels-schist, hornfelses and migmatites, are evident only to the north of the pluton, because the southern margin of it is controlled by a fault system parallel to the contact and the granitoid rocks are thrusted onto the metamorphic rocks. Field and microscopy evidence show that migmatites are injective and occurred by intrusion of granitoid magma into metamorphic rocks. Calculation of garnet-biotite thermometer by all of the average calibrations, account 472° C for equilibrium this two minerals in hornfels. تفاصيل المقالة