Original paper

Reconstructing physicochemical conditions by application of mineral chemistry: a case study from the Natanz pluton, Central Iran

Honarmand, Marayam; Ahmadian, Jamshid; Nabatian, Ghasem; Murata, Mamoru


The Natanz pluton, located north of Esfahan, Urumieh-Dokhtar magmatic belt, is composed of gabbro, diorite, quartz-diorite, quartz-monzonite, granodiorite and granite. These rocks contain plagioclase, quartz, amphibole, alkali-feldspar, biotite and Na-poor pyroxene. Based on chemistry of mafic minerals, the Natanz pluton formed from a calc-alkaline magma in a subduction zone setting. Results of mineral chemistry compare well with those obtained on other granitoids from the Urumieh-Dokhtar magmatic belt. The composition of minerals and the assemblage titanite-magnetite-quartz were used to constrain the P, T and ƒO2 during the crystallization of the Natanz intrusions. Application of Al-in-hornblende barometry indicates pressures of 2.5 to 2.1 kbar. The highest temperature estimate (i.e., 800 °C) comes from amphibole-clinopyroxene thermometry in a dioritic sample. Hornblende-plagioclase thermometry yields a temperature of 705 °C, which probably reflects a late- to post-magmatic re-equilibration of these minerals.


mineral chemistrygeothermometrygeobarometrycalc-alkalineurumieh-dokhtarnatanz