Giuliani Gaston auteur aut IRD Dubessy J. auteur aut IRD Ohnenstetter D. auteur aut IRD Banks D. auteur aut IRD Branquet Y. auteur aut IRD Feneyrol J. auteur aut IRD Fallick A. E. auteur aut IRD Martelat J. E. auteur aut IRD text journalArticle eng text/pdf born digital access The mineral and fluid inclusions trapped by gemstones during the metamorphism of carbonate platform successions are precious markers for the understanding of gem genesis. The nature and chemical composition of inclusions highlight the major contribution of evaporites through dissolution or fusion, depending on the temperature of formation from greenschist to granulite facies. The fluids are highly saline NaCl-brines circulating either in an open system in the greenschist facies (Colombian and Afghan emeralds) and with huge fluid-rock metasomatic interactions, or sulphurous fluids (ruby, garnet tsavorite, zoisite tanzanite and lapis-lazuli) or molten salts formed in a closed system with a low fluid mobility (ruby in marble) in the conditions of the amphibolite to granulite facies. These chloride-fluoride-sulphate +/- carbonate-rich fluids scavenged the metals essential for gem formation. At high temperature, the anions SO4 (2-), NO3 (-), BO3 (-) and F- are powerful fluxes which lower the temperature of chloride- and fluoride-rich ionic liquids. They provided transport over a very short distance of aluminium and/or silica and transition metals which are necessary for gem growth. In summary, the genetic models proposed for these high-value and ornamental gems underline the importance of the metamorphism of evaporites formed on continental carbonate shelves and emphasise the chemical power accompanying metamorphism at moderate to high temperatures of evaporite-rich and organic matter-rich protoliths to form gem minerals. specialized Gems Emerald Ruby Garnet Zoisite Lapis-lazuli Metamorphism Carbonate platform Evaporites Brines Fingerprints Salinity Molten salts Thermal reduction of sulphates COLOMBIE 064 53 1 1-20 2018 0026-4598 https://www.documentation.ird.fr/hor/fdi:010071979 10.1007/s00126-017-0738-4 0026-4598 [F B010071979] https://www.documentation.ird.fr/hor/fdi:010071979 https://www.documentation.ird.fr/intranet/publi/2018/01/010071979.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2018-02-05 2023-07-11 fdi:010071979 fre