Churikova Tatiana, Wörner Gerhard, Mironov Nikita, Kronz Andreas Volatile (S, Cl and F) and fluid mobile trace element compositions in melt inclusions: implications for variable fluid sources across the Kamchatka arc // Contributions to Mineralogy and Petrology. 2007. Vol. 154. № 2. P. 217-239. doi:10.1007/s00410-007-0190-z.
Volatile element, major and trace element compositions were measured in glass inclusions in olivine from samples across the Kamchatka arc. Glasses were analyzed in reheated melt inclusions by electron microprobe for major elements, S and Cl, trace elements and F were determined by SIMS. Volatile element–trace element ratios correlated with ﬂuid-mobile elements (B, Li) suggesting successive changes and three distinct ﬂuid compositions with increasing slab depth. The Eastern Volcanic arc Front (EVF) was dominated by ﬂuid highly enriched in B, Cl and chalcophile elements and also LILE (U, Th, Ba, Pb), F, S and LREE (La, Ce). This arc-front ﬂuid contributed less to magmas from the central volcanic zone and was not involved in back arc magmatism. The Central Kamchatka Depression (CKD) was dominated by a second ﬂuid enriched in S and U, showing the highest S/K2O and U/Th ratios. Additionally this ﬂuid was unusually enriched in 87Sr and 18O. In the back arc Sredinny Ridge (SR) a third ﬂuid was observed, highly enriched in F, Li, and Be as well as LILE and LREE. We argue from the decoupling of B and Li that dehydration of different water-rich minerals at different depths explains the presence of different ﬂuids across the Kamchatka arc. In the arc front, ﬂuids were derived from amphibole and serpentine dehydration and probably were water-rich, low in silica and high in B, LILE, sulfur and chlorine. Large amounts of water produced high degrees of melting below the EVF and CKD. Fluids below the CKD were released at a depth between 100 and 200 km due to dehydration of lawsonite and phengite and probably were poorer in water and richer in silica. Fluids released at high pressure conditions below the back arc (SR) probably were much denser and dissolved signiﬁcant amounts of silicate minerals, and potentially carried high amounts of LILE and HFSE.