Mineral chemistry, petrology, and ore mineralization potential of magmatic rocks NW Takestan (NW Iran)

Document Type : Research Paper


1 Department of Geology, Faculty of Science, Bu-Ali Sina University, Hamedan, Iran.

2 Department of Geology, Faculty of Science, Imam Khomeini International University, Qazvin, Iran.

3 Department of Geology, Faculty of Earth science, Shahid Chamran University of Ahvaz, Ahvaz, Iran.

4 Department of Geological Engineering, Earth Sciences Application and Research Center (YEBIM), Faculty of Engineering, Ankara University, Turkey



In northwest of the Takestan area (NW Iran), as a part of the western Alborz mountain belt, various plutonic (monzodiorite, quartz monzonite, granite, and alkali granite), volcanic (andesite, basalt, basaltic andesite, rhyolite, and dacite) and pyroclastic rocks (tuff, agglomerate, and ignimbrite) are hosted of Eocene age. Electron probe micro analyzing (EPMA) on clinopyroxene, orthopyroxene, biotite, and amphibole show that they are diopside to augite (Mg# = 0.6-0.8), enstatite (Mg# = 0.63-0.68), annite to phlogopite (Fe# = 0.15 - 0.3) and pargasite (Mg# = 0.6 - 0.8), respectively. The plagioclases havedifferent compositions with normal chemical zoning  from labradorite (in the basalts, An% = 40 - 60) to andesine (in the monzodiorite, An% = 27 - 50) to oligoclase (in the other rocks, An% = 13 - 38). All minerals are primary magmatic except for the alkali granite biotites that have low Ti contents which
indicate that they formed by re-equilibrium with a hydrothermal fluid. Chemical compositions of the clinopyroxene, biotite, and amphibole reveal that they crystallized from calc-alkaline magmas formed by subduction of Neo-Tethys oceanic crust beneath the Iran micro-plate. Geothermometry calculations based on the mineral compositions indicate ca. 880 to 980 °C for the basalts, 800 to 850 °C for the andesite and the dacite, 750 to 820 °C for the monzodiorites and the quartz monzonite, and 520 to 670 °C for the alkali granite. High Al contents of the plagioclases from the quartz monzonite and monzodiorite as well as Fe+3 contents of the biotites from the alkali granite show that they formed from oxidized magmas that were suitable for Cu porphyry systems. Propylitic and argillic alteration zones in the area confirm it.


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Article Title [Persian]


Articles in Press, Accepted Manuscript
Available Online from 06 January 2023
  • Receive Date: 31 October 2022
  • Revise Date: 28 December 2022
  • Accept Date: 06 January 2023
  • First Publish Date: 06 January 2023