Petrology
Atefeh Nimroozi; gholamreza ghadami; Jamshid Hassanzadeh; Mohammad posti
Abstract
The study area is located near Abarkoh city and in Sanandaj –Sirjan zone. The volcanic activity of this region is in the form of dacite and rhyolite domes and lava flow and in the petrographic studies includes coarse plagioclase, quartz and hornblende. The volcanic rocks are considered as the separate ...
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The study area is located near Abarkoh city and in Sanandaj –Sirjan zone. The volcanic activity of this region is in the form of dacite and rhyolite domes and lava flow and in the petrographic studies includes coarse plagioclase, quartz and hornblende. The volcanic rocks are considered as the separate units interlayered with calcareous sedimentary units. Geochemical classification confirms the rhyolitic and dacitic composition of the volcanic unites and show their belonging to the calc-alkaline magmatic series, which is the characteristic of the subduction tectonic setting. Significant characteristics observed in spider and multi-element diagrams, such as their enrichment in LREE, high LREE / HREE ratio, Nb and Ti trough, and enrichment of Pb, Rb and Th elements demonstrate the continental crustal contribution to the development of the volcanics and their formation in the subduction environment in the active continental margin setting. Tectonic setting diagrams confirm this idea and determined a continental arc setting for the volcanic rocks of the area. The dating studies on zircon minerals yield the age of about 17.7.2 ± 7.6 ma equivalent to Jurassic for this part of the Sanandaj-Sirjan zone, which matches with the subduction stage of the Neotethyan Ocean below the central Iran zone.
Economic Geology
Hadi Mohammaddoost; Majid Ghaderi; Jamshid Hassanzadeh
Abstract
Sulfur isotope data on pyrite, chalcopyrite and molybdenite in the A, B and D type veinlets in porphyry systems of the Meiduk cluster, located in northwestern part of the Kerman copper belt, show that these systems have near zero δ34S values. Sulfur isotope composition for the Chah-Firouzeh and ...
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Sulfur isotope data on pyrite, chalcopyrite and molybdenite in the A, B and D type veinlets in porphyry systems of the Meiduk cluster, located in northwestern part of the Kerman copper belt, show that these systems have near zero δ34S values. Sulfur isotope composition for the Chah-Firouzeh and Iju deposits and Serenu, God-e-Kolvari and Kader prospects is from -1.4 to +2.5 (average +0.31), -1.3 to +1.1 (average +0.07), +0.1 to +2.4 (average +0.87), -1.5 to +0.2 (average -0.1) and -4.1 to +1 (average -1.04), respectively. These results suggest a magmatic source for sulfur. Also, limited range of isotopic variations and analogous isotopic composition for the three types of veinlets reveals that with evolution of the hydrothermal system, no significant changes occurred in the primary and relatively homogenous source of sulfur. Comparison between the data for the Meiduk cluster with available data from other deposits in middle and southern parts of the Kerman belt suggested that in porphyry systems of the northwestern, and to some extent southern parts, of the Kerman Cenozoic magmatic arc, sulfur was provided by a mafic magma originated from metasomatized subcontinental lithospheric mantle (SCLM) which was affected by assimilation with continental crust; while in the southern parts, processes related to subduction and fluids from seawater and associated sediments had a major role in their sulfur isotope composition.