Document Type : Original Article
Authors
1
Department of Geology, Faculty of Earth Science, Shahid Beheshti University, Tehran, Iran
2
Assistant Professor, Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences, Zanjan.Iran
3
Department of Mineral Resource and Groundwater, Faculty of Earth Sciences, Tehran, Iran
4
Department of Mineral Resource and Groundwater, Faculty of Earth Sciences, Tehran, Iran,
5
Department of Geology, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz,,Ahvaz, Iran
Abstract
Dalampar ophiolite mélange is an uncharacterized segment of the Neotethys ophiolite, situated between the Sardasht and Selmas ophiolites northeast of Oshnavieh city, at the end part of the Sanandaj-Sirjan metamorphic belt. The main rock types in the area include serpentinized peridotites, pillow basalts, various gabbros, pelagic limestone, radiolarite, and volcano-sedimentary units. Gabbros can be classified into two types: coarse-grained with a pegmatitic texture, and fine-grained gabbros occurring as masses and dikes. They primarily consist of plagioclase (50–60% by volume) and clinopyroxene (20–30% by volume). Secondary minerals in these rocks include sericite, chlorite, calcite, tremolite-actinolite, and epidote. According to mineral chemistry investigations, the compositions of clinopyroxene, amphibole, and plagioclase minerals range from diopside to augite, magnesiohornblende, and oligoclase to labradorite, respectively. According to geothermometric calculations, clinopyroxenes formed at pressures of 5 to 10 kbar, temperatures between 900 and 1200 °C, and under conditions of high oxygen fugacity. The chemical compositions of clinopyroxene and amphibole indicate that these minerals crystallized from a sub-alkaline magma typical of island arc tholeiites (IAT) and boninites found in subduction zones.
Keywords
Main Subjects
)