تشكيل كروميت و ژيوشيمي عناصر گروه ژلاتين و نادر خاكي همراه آن در مجموعه معادن خواجه جمالي

Occurrence and geochemistry of chromite mineral, PGE(S) and REE in the Khaj-e-Jamali-Mines-Neyris-Iran

The Khajeh-e-Jamali chromite mines are located in southwestern Iran, about 100 km north-west of Neyriz and 150 km north-east of the city of Shiraz. Field, microscopic and geochemical studies indicate that partial melting, magmatic segregation and magmatic miscibilty were responsible for the generation of the Khajeh-e-Jamali deposits. MORB and boninitic magmatic series are considered to have formed this Alpine type deposit. Ru, os and Ir enrichment in chromite and in host rock (dunite and harzburgite) implies the deficiency or lack of sulphur phase and hence higher values of f o 2 during the crystallization. Similarity in the correlation pattern of [Al, Ir] and [Cr, Ir] , positive correlation of Ir and Cr , lower value of fs in early stages of crystallization, association of varions phases, lack of preffered orientation of platin group metals (PGM) in chromite crystals and double - phase inclusions indicate a similarity in the deposition of Cr and PGM from a boninitic melt, simultaneous crystallization of chromite and IPGMs during the slow cooling or fractional crystallization and mixing of boninitic magma with a silica bearing liquid (tranzitional zone gabbro), lack of exsolution and the association of PGMs with chromite composition. Wide v-shaped pattern of REE spider diagram is a confirmation of partial melting and the presence of boninitic series.