Geothermobarometry of amphiboles in intermediate to basic rocks from the Almogholagh pluton in western Iran

Abstract

In this study, some barometries and thermometries were used to calculate the crystallization temperature and pressure of amphiboles in intermediate to basic rocks from the Almogholagh pluton in western Iran. Intersection among geothermometers was introduced as a method to estimate crystallization temperature, and the results obtained were compared with those of other methods. Results showed that obtaining the average pressure from the intersections between geothermometers and geobarometers is a suitable approach to determine the crystallization pressure of the analyzed points of amphiboles, whereas the crystallization temperature can be appropriately determined from the intersection among geothermometers. In addition, the average temperature of the HB 2 94 geothermometer is approximately equal to the average temperature in intersection among geothermometers. HB 2 94 is apparently a suitable geothermometer to determine the crystallization temperature in intermediate to basic rocks. In this study, the average crystallization temperature and pressure using intersection methods were 714-719°C and 6.5-7.5 kbar, respectively. Adopting these methods to the Almogholagh pluton, intermediate to basic rocks intruded at a depth of 24-28 km of the crust and at 674-759°C.

Geothermobarometry of granitic pegmatites of Nagamalai - Pudukottai area, Madurai Block, South India

“…Geobarometry based on Al content in amphiboles is widely used and this in turn helps to determine the depth of emplacement (Ghent et al, 1991;Ague and Brandon, 1992;Anderson andSmith, 1995 andAmiri et al, 2016). Based on Al tot content, Hammarstorm and Zen (1986) and Hollister et al (1987) proposed hornblende geobarometry (empirical geobarometers), for a rock containing quartz + plagioclase + alkali feldspar + hornblende + biotite + titanite + an oxide phase (Magnetite and ilmenite).…”