Pressure, temperature and oxygen fugacity conditions of Ganj dioritic-quartz dioritic intrusives, west of Makran, and its tectonomagmatic implication


1 Department of Mining Engineering, Higher Education Complex of Zarand, Shahid Bahonar University, Kerman, Iran

2 Department of Geology, College of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran


The Ghaleh-Ganj dioritic- quartz dioritic massifs, with the age of Paleocene-Eocene, located on the west side of the Makran accretionary prism and Jazmurian depression and the east side of Jiroft fault are part of the intrusives in the Ganj Complex which itself is a part of the Jazmurian ophiolitic belt or Inner Makran. These intrusives rocks show microgranular to granular texture and consist of plagioclase, clinopyroxene, amphibole, biotite, quartz, K-feldspar, titanite, apatite and opaque as primary minerals along with chlorite, calcite, clay minerals, sericite and iron oxides as secondary minerals. Based on mineral chemistry studies, the plagioclases are oligoclase to labradorite in composition and predominantly fall in the field of andesine. Considering the total content of Fe in plagioclases, it seems that they were formed in high fO2 conditions. The existence of disequilibrium textures in plagioclases show variations of PH2O and decompression along with minor loss of temperature during the magma ascent to the surface. Clinopyroxenes display augitic composition and are belonging to a tholeiitic magmatic series and formed in 1133- 1382°C temperature, pressure less than 10 kbars and high fO2 conditions. Amphiboles have magnesiohornblende compositions which are estimated to have been formed at 650- 700°C temperature, less than 1 kb pressure and high fO2 conditions in a supra-subduction tectonomagmatic environment.