GhodratiShahMohamadi F, Nasrabady M, Ahmadvand A, Gholizadeh K, Armani P. Petrology of rhyolite-trachytes from the Rizu Formation in the Zarand area (NW Kerman). KJES 2022; 8 (1) :144-167
URL:
http://gnf.khu.ac.ir/article-1-2862-en.html
1- Imam Khomeini international University, Qazvin
2- kharazmi University , ahmadvand.akbar1984@gmail.com
3- Mineral Holding of Copper Star, Ahang-e-Tejarat-e- Niko Company
Abstract: (566 Views)
The Rizu Formation of the Zarand area consists of felsic (rhyolite-trachyte) and mafic (microgabbro-dolerite) magmatic suites, overlain by dolomites of the Desu Formation. Felsic magmatic units are investigated in this research. The rhyolite-trachytes of the Rizu Formation are composed of alkali feldspar microphenocrysts that have been enclosed by fine grained and micro granular groundmass consisting of quartz, alkali feldspar and plagioclase. Whole rock geochemical data indicate that the samples are metaluminous with high FeO/MgO ratio, Na2O+K2O and HFSE, and low CaO, Ba and Eu contents that are in line with geochemical characteristics of anorogenic granites. According to the tectonic discrimination diagrams, the felsic rocks of the Rizu Formation were formed in within plate to continental rift settings. They show the same geochemical signatures as those of anorogenic rhyolites of the East African rift and Basin and Range province of the west coast of North America. In addition, the rhyolite-trachytes of the Rizu Formation suggest an A1 subtype on the basis of anorogenic granite discrimination diagrams, derived from fractional crystallization of an OIB-type mantle melt in a within plate (failed rift) environment. Their association with microgabbros is also reminiscent of bimodal magmatism in a continental back arc rift formed by the subduction of Prototethys beneath the Iranian plate during the Late Neoproterozoic-Cambrian
Type of Study:
Original Research |
Subject:
Petrology Received: 2022/05/3 | Accepted: 2022/08/21 | Published: 2022/09/17