جستجوی مقالات مرتبط با کلیدواژه "tectonic environment" در نشریات گروه "زمین شناسی"

Intrusive masses are exposed in the Bostanabad-Mianeh axis with the northwest-southeast trend. The rocks are known as granite in general geological maps. Detailed studies in this study have also shown the presence of syenites which their petrology was considered in order to investigate the Zagros orogeny development in northwestern of Iran. The magmatic rocks of the region are the result of magmatism of the Uromieh-Dokhtar magmatic belt and include intrusive, volcanic and pyroclastic rocks with sedimentary units. Syenites of the Bostanabad-Mianeh axis are along with large volume of granites. Syenites provides important information about the interaction of the crust-lithosphere mantle, magma evolution processes, tectonics and crustal growth. In this study, syenites are divided from granitic rocks and their geochemical properties have been investigated to determine their tectono-magmatic and Petro-genetic conditions.

During field study, samples from the syenite and granite outcrops were collected for petrography, geochemistry and determining magmatic series and the magma origin. For geochemical studies, 13 samples of intrusive rocks with the lowest degree of alteration were chemically analyzed by ICP-MS and ICP-OES methods in the Act Lab Ontario Canada.

The Bostanabad-Mianeh axis in northwestern of Iran and in the East Azerbaijan province is part of the Cenozoic magmatism of the Lesser Caucasus towards southeastern Iran. Magmatism is related to the subduction of the northern ocean of Neotethys during the collision of the Arabian Plateau with Eurasia and its subsequent events. The presence of arc-type magmatism in the regions of Azerbaijan, the Alborz Mountains, Talesh and the Lesser Caucasus all indicate the subduction of the Neotethys branch with the Eurasian plate. Due to the LILE and LREE enrichment and the HREE depletion, the source of the magmas for the studied syenites are originated from an enriched mantle source in the continental lithosphere in the subduction zone belonging to post orogenic extension events. Consequently, the formation of the intrusions is related to mantle melting which is enriched and fed by fluids and melts and finally contaminated with crustal material during the ascent.

The exposed volcanic rocks in south west of the Khoy area consist of basalts with minor amounts of plagioclase-phyric basalts. These rocks are composed of clinopyroxene plus plagioclase and plagioclase phenocrysts, respectively. The basaltic rocks are highly altered and contains high amounts of secondary minerals mainly chlorite and epidote. According to mineral chemistry, the composition of clinopyroxenes varies from diopside to augite. The clinopyroxenes are characterized by normal zoning and were formed from a primitive subalkaline magma. The studied clinopyroxenes were crystalized at pressure of 2 to 5 kbars, temperature ranging from 1100- 1150 °C and high oxygen fugacity. On the tectonic setting discrimination diagrams, the south west of Khoy basalts plot mainly in the areas of overlap between IAT, BABA and MORB. The comparison between studied basalts and basaltic rocks in the Khoy ophiolitic complex reveal that the south west of Khoy basalts might have been formed in back- arc basin settings.

Ophiolite outcrops and ophiolite clusters have spread widely in Iran. Ophiolite is referred to as a collection of mafic and voltramaphic rocks, which may be ordered or layered or interconnected by tensile stresses. Ophiolite; ophiolite complex, ophiolite series, was finally told that the color combination of the words' color combination (Kalrd melange) more applications. Due to the variety of research done in this field and the lack of a review article, a new research work has been done. The purpose of this article is to review the geochemistry and tectonic environment of the formation of ophiolitic zones of Iran. The results of this research show that in terms of dispersion, Iranian ophiolites are a type of melange that can be distinguished in the two groups of Zagros radiolarite ophiolite strips and Central Iranian tape. In the southwest of Zagros, there are two separate parts, called Ophiolite, Kermanshah and Nayriz. Central ophiolites, which are named after the submarine strips of central central (Sabzevar, north of Torbat Heydarieh, south of Birjand) and east of central Iran (Mako-Khoy, northern Makran and northern Nain) due to subduction, part of the upper mantle and the crust The ocean is left in the form of an ophiolite melange. Also, the results of many geochemical studies on Iranian ophiolites have shown the dependence of Mid-ocean ridge basalts (MORB) and island arc tholeiitic (IAT. Both groups of subalkaline and alkaline basalts have been identified in the ophiolites of Kermanshah. In the ophiolites of Neyriz and Babak, several types of basalt that have IAT attributes have been identified and reported. The chemical composition of Sabzevar ophiolite also shows the geochemical characteristics of the IAT type. Two types of basaltic lava have also been identified in the Ophiolite of the Ziarat (Bakhtar Makran).