Articles
Zarei e., E.,
Kananian, A.,
Nakashima k., ,
Tadayon, M. Geotectonics (15561976)57(1)pp. 115-133
Abstract: The Ashin ophiolitic mélange is located along the curve of the Doruneh fault system in the western corner of the Central Iranian microplate. The rock units of the ophiolitic massive due to tectonic events are located in the serpentinite matrix. The crustal rocks of oceainic crust include tectonic slices of sheeted dykes, pillow lavas, and massive basalts covered by radiolarian chert, rodingite, and globotroncana limestone. Microprobe analysis results indicate that mineral association of pillow lavas are clinopyroxene (augite), hornblende, plagioclase, calcite, ilmenite, and magnetite; massive basalt consists of clinopyroxene (augite), hornblende, plagioclase (albite), ilmenite and magnetite; dyke is composed of clinopyroxene (diopside and augite), plagioclase (albite), chlorite and prehnite. Microscope studies reveal porphyritic and intersertal as the most common textures of this rocks. Barometry indicates these rocks formed in medium to low pressure (2 to 5 Kbar) during their ascending, also, thermometry calculations indicate temperatures of 1100°C to 1200°C for clinopyroxene crystallization. Clinopyroxene compositions are similar to those of both boninites and island-arc tholeiites. The occurrence of high-Mg and low-Ti magma constrains the formation of these rocks in a supra-subduction environment. The water content in the crystallization of pyroxenes is more than 10% and those are formed in high oxygen fugacity. The clinopyroxenes of lava and associated dyke of the Ashin ophiolitic mélange have similar chemical compositions to those of the other supra-subduction zone type Eastern Mediterranean ophiolites that show island arc affinity. © 2023, Pleiades Publishing, Inc.
Beygi s., S.,
Tadayon, M.,
Ilalova r.k., ,
Talovina i.v., I.V.,
Meisel, T.C. Geodynamics and Tectonophysics (2078502X)14(2)
Within the Urumieh-Dokhtar Magmatic Arc in the central part of Iran, the formation of which is associated with the Neotethys closure, there are many porphyry copper deposits and ore occurrences. One of them is the Astaneh porphyry copper ore deposit, located in the central part of the Saveh-Ardestan ore region southeast of Ardestan city. The purpose of this study is to investigate the petrochemical characteristics of rocks and to determine the relationship between the distribution of porphyry copper mineralization and tectonic position of faults within the study area. To achieve the goal, there were used the structural and geological data obtained in the fieldwork, as well as the results of mineralogical and geochemical analyses. The obtained results show that rocks of different composition of the Astaneh ore deposit (andesite, andesite-basalt, basalt, trachybasalt) were formed in the suprasubduction zone, and probably in the environment prior to the collision of the of continental plates. Paragenetic relationships and mineralogical analysis show that the evolution of mineralization of the Astaneh ore deposit can be divided into three stages: pre-ore, hypogene and supergene mineralization. Geochemical research based on the study of the content of the major chemical elements in the rocks of the region shows that igneous rocks belong to calc-alkaline basalts and geodynamically can be attributed to the products of magmatism of the ensial island arc. The results concluded that the main stages of the formation of a porphyry copper ore deposit in the study area attain maximum spatio-temporal similarity with the tectonomagmatic phases of the development of the Neotethys Ocean. In addition, the Southern Ardestan fault, running through the study area and intersecting the basement structures, forms wide permeable zones favorable for the formation of porphyry copper deposits therein. © Beygi S., Tadayon M., Ilalova R. K., Talovina I. V., Meisel T. C., 2023.
Journal of Structural Geology (01918141)160
The Central Iranian Micro-plate (CIM) is a dismembered piece of northern Gondwana. The aim of this study is to reconstruct the post-Early Cretaceous structural evolution of the western edge of CIM in the light of the integration of regional to the micro-scale structural data with minor Anisotropy of Magnetic Susceptibility (AMS) analyses. Our original field measurements on the structural architecture of the study area show main NW-SE and E-W structural trends that are accompanied by structural evidence for superposition. However, paleostresses obtained from fault and fold analysis (stress inversion method on faults and statistically π-plane and β-axis solution on folds), statistical Fry center-to-center analysis on the oriented thin-sections integrated with AMS results suggest that the study area has experienced a NE-SW-directed compressional regime since Paleocene time followed by a post-Early Miocene, roughly N–S-directed, regional compressional regime. Furthermore, the results of this work confirm the consistency between regional-micro structural analysis and AMS analysis. The most of samples show composite (sedimentary + tectonic) magnetic fabric and intermediate arrangement in the orientation of the magnetic fabric. Reconciling our results with published structural and AMS data suggests the changes in the regional stress regime in the western CIM has been occurred in response to the long-term stress transition from the infant Late Cretaceous–Paleogene subduction of the Neo-Tethys Ocean to the mature Cenozoic stages of the Zagros collision and the consequent Neogene tectonic reorganization in the hinterland domains of the southern Eurasian plate. © 2022 Elsevier Ltd
Beygi s., S.,
Talovina i.v., I.V.,
Tadayon, M.,
Pour, A.B. International Journal of Image and Data Fusion (19479832)12(2)pp. 155-175
Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery was used to identify argillic, phyllic and propylitic alteration zones and mapping geological structural features for porphyry copper exploration in the Kacho-Mesqal zone, Urumieh- Dokhtar Magmatic Arc, Iran. The image processing techniques such as specialised band ratio, Selective Principal Component Analysis (SPCA), and Spectral Angle Mapping (SAM) image processing methods were implemented to the visible and near-infrared and shortwave infrared bands of ASTER. Results indicate that the argillic alteration zone is broadly distributed in the granodiorite intrusion, andesitic rock, tuff breccia and ignimbrite. Phyllic alteration is mainly mapped associated with sandstone and some parts of andesitic lithology. Propylitic alteration zone is identified in andesite, sandstone, shale and marl, dacite to rhyodacite, andesite-basalt, tuff and andesite lava and granodiorite intrusion. The fracture density map shows that the argillic alteration is mostly abundant in the high-density fracture zone, whereas propylitic and phyllic zones are located in moderate to low-density fracture zones. Consequently, high potential zones for copper mineralisation in the study area are identified within the high to moderate fracture density zones associated with argillic and assemblage of argillic, phyllic and propylitic alteration zones in granodiorite and andesite units. © 2020 Informa UK Limited, trading as Taylor & Francis Group.
Petrological Journal (22285210)12(2)pp. 125-148
Anarak ophiolite, belonging to Paleozoic, formed along with the tectonic evolution of the Paleo-Tethys Ocean, consisting of meta-peridotites of mantle and crust, cumulate rocks, massive gabbros, pillow lava, basic and ultrabasic dikes, rodingite and listwanite covered all by schist and marble units. The olistolithic patches of Anarak ophiolite have commonly exposed in Sebarz schist, within the sole of Chah-Gorbeh complex. Olistoliths composed of listwanite, meta-mafic, serpentinite and meta-peridotite olistoliths varying from centimeter to several hundred meters in size. The results of electron microprobe analyses show that the fundamental rock-forming minerals of the listwanitized olistoliths are chromian spinel and pyroxene, secondary minerals including calcite, garnet, tremolite, chlorite, magnetite and opaque minerals. Meta-mafic olistoliths composed of chromian spinel, sphene, epidote, chlorite and opaque minerals. Serpentinized olistoliths consist of chromian spinel, magnetite, tremolite, talc and chlorite. It also shows that the meta-peridotite olistoliths composed of chromian spinel, chrome-bearing magnetite, chlorite, calcite, garnet and antigorite. Based on the geochemical analyses, Cr# in the listwanite patches, meta-mafic, serpentinite and meta-peridotite olistoliths are 87.40-97.92, 49.38-51.89, 49.22-60.05 and 29.76-55.97 respectively with very low amount of TiO2. The different in chemical composition of minerals in the North Anarak complex shows different petrogenesis for ophiolitic olistoliths suggests characteristic of the MORB and/or supra-subduction zone. © 2021 The Authors. Published by University of Isfahan.
