Investigation of petrology, tectonic setting and ore mineralization potential of basic rocks in north of the Alvand complex using amphibole and plagioclase mineral chemistry

Saki, Adel; Miri, Mirmohammad; Soltanimehr, Sakineh; Rezaei, Mohsen

doi:10.52547/gnf.6.2.321

Volume 6, Issue 2 (Autumn&Winter 2021) KJES 2021, 6(2): 321-342 | Back to browse issues page

‎ 10.52547/gnf.6.2.321

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Saki A, Miri M, Soltanimehr S, Rezaei M. Investigation of petrology, tectonic setting and ore mineralization potential of basic rocks in north of the Alvand complex using amphibole and plagioclase mineral chemistry. KJES 2021; 6 (2) :321-342
URL: http://gnf.khu.ac.ir/article-1-2757-en.html

Investigation of petrology, tectonic setting and ore mineralization potential of basic rocks in north of the Alvand complex using amphibole and plagioclase mineral chemistry

Adel Saki ^*

¹, Mirmohammad Miri²

, Sakineh Soltanimehr²

, Mohsen Rezaei²

1- Shahid Chamran University of Ahvaz , adel_saki@scu.ac.ir
2- Shahid Chamran University of Ahvaz

Abstract: (1405 Views)

The Alvand complex (Hamedan province) comprises several bodies ranging from acidic to intermediate and basic compositions intruded in the regional metamorphic sequence of the area (the Hamedan phyllites) during various magmatic episodes in Jurassic. In northern part of the complex (the Cheshmeh-Ghasaban area) there are some outcrops of hornblende gabbro and olivine gabbronorite. The olivine-gabbronorites are composed of olivine, clino- and ortho-pyroxene, plagioclase and hornblende. Apatite, magnetite, titano-magnetite, pyrite and chalcopyrite are the accessory minerals. The alterations include substitution of the olivine and pyroxene by bolingite, serpentine and chlorite. Electron microprobe analyses show that the amphiboles are of pargasite, and magnesio-hornblende. Variations of MgO, Al₂O₃ and Na₂O and thermobarometry calculations based on amphibole and plagioclase compositions indicate that pargasites formed in average pressure and temperature of 11 kbar and 835°C, from metasomatized mantle derived melt as a result of asthenospheric mantle elevation and in extensional setting. Mafic magma contaminated with crustal material as it ascends. This situation can be provided in a rift setting (probably a back arc basin). Investigation of Fe and Ti concentration variations in the plagioclases indicates that differentiation trend of the parental magma was not consistent with concentration of these elements in the melt. High fO₂ and slow cooling rate of the magma caused Fe-depletion during plagioclase crystallization. In addition, formation from a Fe-depleted source could be another factor that limited iron mineralization of the Cheshmeh-Ghasaban olivine-gabbronorite.

Keywords: Olivine gabbronorite, Amphibole chemistry, Iron mineralization potential, Alvand complex.

Full-Text [PDF 2031 kb] (580 Downloads)

Subject: Petrology
Received: 2020/06/30 | Accepted: 2020/12/22 | Published: 2021/02/28