F. Rostami; M. Delavari; S. Amini; A. Dolati
Abstract
The Permian volcanic rocks of Central Alborz (northeast of Baladeh- Siahbisheh) crop out between Ruteh and Nesen Formations. The volcanic rocks are predominantly basaltic and plagioclase- phyric. Ferromagnesian minerals such as clinopyroxene and olivine are not modally abundant and sometimes are totally ...
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The Permian volcanic rocks of Central Alborz (northeast of Baladeh- Siahbisheh) crop out between Ruteh and Nesen Formations. The volcanic rocks are predominantly basaltic and plagioclase- phyric. Ferromagnesian minerals such as clinopyroxene and olivine are not modally abundant and sometimes are totally altered. Based on microprobe data, clinopyroxene and plagioclase are diopside (En34.2-36.4 Wo43.1-47.2 Fs14.9-18.1) and labradorite (50<An%<55), respectively. Clinopyroxene and plagioclase geothermobarometric calculations shows the temperature and pressure ranges of 1050 to 1200 °C and 2 contents (4.94- 7.24 wt. %). Clinopyroxene chemical data display that the parent melt was alkaline basalt, generated in a within plate setting. On the basis of our findings it can be stated that, Central Alborz was a continental passive margin in middle- late Permian at south of Paleo-Tethys and its magmatism was likely triggered by late Paleozoic extensional tectonism of northern margin of Gondwana during the early stages of Neo-Tethyan development.
