Petrography, Mineral Chemistry and Geothermobarometry of Gabbro-Diorite intrusions from Hurjand Area, NE of Kerman

Gabbroic-dioritic rocks of Hurjand area northeast of Kerman within the Posht-e-Badam block of the Central Iran microcontinent have intruded into the Precambrian-Cambrian sedimentary units of Desu Series. Amphibole, pyroxenes and plagioclase are the main minerals of these rocks. Also, granular and poikilitic are dominant textures of these rocks. Mineral chemistry studies show that clinopyroxene composition is augite and diopside. The plagioclase has a range of chemical composition from bytownite (An75.2Ab23.8Or1.1) to andesine (An40.2Ab55.9Or3.9). Amphibole crystals present in these rocks are calcic and magmatic types with chemical composition of magnesio-hastingsite. Thermometry by utilizing of Ti content in amphibole composition shows range of crystallization temperatures from 769 to 889°C. Also, based on coexisting amphibole-plagioclase pair geothermometry, shows the temperature ranges from 793 to 896°C for crystallization temperatures these two minerals. Results of the geobarometry show that amphibole crystals formed at pressure of about 6.3 to 8.8 kbar, equivalent to the depth of 23 to 30 km. Mineral chemistry studies indicate the formation of these rocks from magma of alkaline to sub-alkaline nature related to intra-plate tectonic setting.