عنوان مقاله English
نویسندگان English
Majerad igneous-metamorphic complex is located in the southeast of Shahrood and in the northern edge of the central structural zone of Iran. Metarhyolites are important compositional constituent of this complex and cropped out in the form of domes and/or intercalations with calcitic and dolomitic marbles, metapelites and metapsammites. Foliation and lineation were developed in metarhyolites due to metamorphism and mylonitisation. Based on the geochemical evidence, metarhyolites have medium to high-K calc-alkaline nature. These rocks are enriched in light rare earth elements (except Eu) with respect to heavy rare earth elements in primitive mantle normalized REEs diagram, and enriched in U, Th, Pb and K, and depleted in Zr Ti, P, Sr, and Nb in primitive mantle normalized spider diagram. Metarhyolites are dry or high temperature rhyolites and formed in intracontinental extensional setting. U-Pb dating of separated zircons from the metarhyolites, indicating 587.6 to 508 Ma (Late Neoproterozoic-Early Cambrian), but according to the age of granitoid which cutts this complex (553 ± 3.8 Ma), Late Neoprotrozoic (Ediacaran) is more reasonable age for the metarhyolites, which endorses their belonging to crystalline basement and Gondoanwan terrains of Iran.
کلیدواژهها English
