Paragenetic relationships of clintonite and spinel in Central Iran skarns as evidence of the formation of clintonite

Abstract

In Central Iran, granodiorite of the Cenozoic magmatic arc intruded into Cretaceous carbonate rocks causing various generations of skarn to be formed. Two occurrences of the rare mineral clintonite were studied in the Shir-kuh and Feshark polygenic skarns. Characteristical assemblages were found to be garnet+spinel+clintonite+phlogopite+vesuvianite (Feshark area) and fassaite+spinel+clintonite+melilite+phlogopite+vesuvianite (Shir-kuh area). The genesis of clintonite was investigated in detail on the basis of the textural relationships between spinel, clintonite, garnet and pyroxene. Gradual and pseudomorphic replacement of grossular and fassaite by spinel was evident. These reactions suggest a temporal Al-leaching process in the skarn evolution stages. Spinel or other minerals could then take part in another reaction to form clintonite. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.