Petrology
M. Sadeghian; S. H. Hosseini; A. Hemmati; S. Shekari
Abstract
Granitoid plutons of SW Mayamey (60 Km east of Shahrood), located at the most northern margin of the central Iran structural zone, have granite composition (in general) and calk alkaline and peralouminous nature. In spite of coverage of these granitoids by Late Triassic – Early Jurassic sedimentary ...
Read More
Granitoid plutons of SW Mayamey (60 Km east of Shahrood), located at the most northern margin of the central Iran structural zone, have granite composition (in general) and calk alkaline and peralouminous nature. In spite of coverage of these granitoids by Late Triassic – Early Jurassic sedimentary rocks, Late Neoproterozoic host gneiss are exposed in limited areas. These granitoids invaded by two series of the Late Neoproterozoic and middle Jurassic diabasic dikes. Although post – Liass, Pre- Dogger, younger than Jurassic and older than Cretaceous ages are considered for these granitoids, but for the first time U–Pb age dating on separated zircons indicates Late Neoproterozoic age (Late Ediacaran) (545±10 Ma) for them and they are a part of very ancient basement rocks of Iran. The studied rocks are similar Band -e-Hezar Chah, Sefid Sang, Delbar, Shotor Kuh, Reza Abad and Do Chah granitoids in age. Mayamey granitoids are resulted from partial melting of metapelites and metagraywackes, and they belong to S-type granioids. SW Mayamey granitoids were generated in a collisional tectonic setting in the Late Neoproterozoic, in relation to closing of intracontinental back arc basin and then metamorphism of the associated rocks from greenschist facies to amphibolite and rarely granulite facies, which finally companied with s-type granitization
M. Sadeghian; M. Sheibi; S. Badallo
Abstract
The Gol-e-Zard granitoidic pluton with an age of ~ 165±5 Ma is located in the north of Aligoudarz city, Lorestan province, in the Sanandaj-Sirjan structural zone. The pluton intruded into the late Triassic-early Jurassic slates, phyllites and micaschists. The granodiorites, dominant rock types ...
Read More
The Gol-e-Zard granitoidic pluton with an age of ~ 165±5 Ma is located in the north of Aligoudarz city, Lorestan province, in the Sanandaj-Sirjan structural zone. The pluton intruded into the late Triassic-early Jurassic slates, phyllites and micaschists. The granodiorites, dominant rock types of the pluton, are cut by the leucogranites, aplitic veins, pegmatites and gabbro-dioritic dykes. The S-type nature of the Gol-e-Zard granite is evidenced by the presence of metaplitic enclaves (surmicaceous and andalusite-sillimanite hornfels), silica enclaves, andalusite and garnet xenocrysts and silica veins relicts. The anisotropy of magnetic susceptibility (AMS) method was used to investigate the mode of emplacement. The total numbers of 868 oriented core samples were analyzed for magnetic susceptibility. The obtained mean susceptibility (Km) in µЅІ was 227, 57 and 585 for granodiorites, leucogranites and gabbrodiorite dykes, respectively. The low Km values (
