A new view on the metamorphic rocks of the Boroujerd area
محورهای موضوعی : Engineering geology
Ahmad Ahmadi-Khalaji
1
(Department of Geology, Faculty of Science, University of Lorestan, Lorestan, Iran)
Zahra Tahmasbi
2
(Department of Mining, Faculty of Engineering, University of Lorestan, Lorestan, Iran)
Shahriar Keshtgar
3
(University of Applied Science and Technology, Sistan & Baluchistan Province, Zahedan, Iran)
کلید واژه: Boroujerd, Metamorphism, hornfels, Sanandaj-Sirjan Zone, Migmatite,
چکیده مقاله :
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.
