Conditions of metamorphic rocks of Prehnite-ActinoliteAnd Green schist Facies in Crustal sequence of Ophiolitic Complex of Eastern Birjand

Category Petrology
Group GSI.IR
Location 21th symposium on geosciences
Holding Date 21 May 2008

      Eastern Birjand ophiolitic complex consists of rocks of a complete ophiolitic complex. With the acceptance of basaltic pillow lava that are changed to metabasite under metamorphism conditions, all other types of rocks related to ophiolitic complex, could be seen in this sequence.
   Carefully study of rocks of this sequence indicates that most crustal part of the sequence has experienced a very low-grade metamorphism, that is, zeolite and prehnite- actinolite facies and a low grade one, that is, Green schist facies. Moreover, laboratory studies, thermobarometry calculations and phase diagram of prehnite bearing mineral assemblages, particularly within metamorphosed diabasic sheeted dykes, indicate that prehnite- actinolite metamorphic facies were taken place under conditions of 200-300?C and 1.5-4 kbars within crustal sequence of ophiolitic complex. Thermobarometry results on Green schist samples based on Thermocalc software indicate a temperature range of 388-496?C in selected pressures of 2 to 8 kilo bars.
   Keywords: Birjand, Ophiolitic complex, Crustal part, Prehnite-actinolite facies, Thermobarometry