Metamorphic and Metasomatic Kyanite-Bearing Mineral Assemblages of Thassos Island (Rhodope, Greece)
AbstractThe Trikorfo area (Thassos Island, Rhodope massif, Northern Greece) represents a unique mineralogical locality with Mn-rich minerals including kyanite, andalusite, garnet and epidote. Their vivid colors and large crystal size make them good indicators of gem-quality materials, although crystals found up to now are too fractured to be considered as marketable gems. The dominant lithology is represented by a garnet–kyanite–biotite–hematite–plagioclase ± staurolite ± sillimanite paragneiss. Thermodynamic Perple_X modeling indicates conditions of ca. 630–710 °C and 7.8–10.4 kbars. Post-metamorphic metasomatic silicate and calc-silicate (Mn-rich)-minerals are found within (i) green-red horizons with a mineralogical zonation from diopside, hornblende, epidote and grossular, (ii) mica schists containing spessartine, kyanite, andalusite and piemontite, and (iii) weakly deformed quartz-feldspar coarse-grained veins with kyanite at the interface with the metamorphic gneiss. The transition towards brittle conditions is shown by Alpine-type tension gashes, including spessartine–epidote–clinochlore–hornblende-quartz veins, cross-cutting the metamorphic foliation. Kyanite is of particular interest because it is present in the metamorphic paragenesis and locally in metasomatic assemblages with a large variety of colors (zoned blue to green/yellow-transparent and orange). Element analyses and UV-near infrared spectroscopy analyses indicate that the variation in color is due to a combination of Ti4+–Fe2+, Fe3+ and Mn3+ substitutions with Al3+. Structural and mineralogical observations point to a two-stage evolution of the Trikorfo area, where post-metamorphic hydrothermal fluid circulation lead locally to metasomatic reactions from ductile to brittle conditions during Miocene exhumation of the high-grade host-rocks. The large variety of mineral compositions and assemblages points to a local control of the mineralogy and fO2 conditions during metasomatic reactions and interactions between hydrothermal active fluids and surrounding rocks. View Full-Text
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Tarantola, A.; Voudouris, P.; Eglinger, A.; Scheffer, C.; Trebus, K.; Bitte, M.; Rondeau, B.; Mavrogonatos, C.; Graham, I.; Etienne, M.; Peiffert, C. Metamorphic and Metasomatic Kyanite-Bearing Mineral Assemblages of Thassos Island (Rhodope, Greece). Minerals 2019, 9, 252.
Tarantola A, Voudouris P, Eglinger A, Scheffer C, Trebus K, Bitte M, Rondeau B, Mavrogonatos C, Graham I, Etienne M, Peiffert C. Metamorphic and Metasomatic Kyanite-Bearing Mineral Assemblages of Thassos Island (Rhodope, Greece). Minerals. 2019; 9(4):252.Chicago/Turabian Style
Tarantola, Alexandre; Voudouris, Panagiotis; Eglinger, Aurélien; Scheffer, Christophe; Trebus, Kimberly; Bitte, Marie; Rondeau, Benjamin; Mavrogonatos, Constantinos; Graham, Ian; Etienne, Marius; Peiffert, Chantal. 2019. "Metamorphic and Metasomatic Kyanite-Bearing Mineral Assemblages of Thassos Island (Rhodope, Greece)." Minerals 9, no. 4: 252.
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