Giuliani Gaston, Fallick A. E., Feneyrol J., Ohnenstetter D., Pardieu V., Saul M. (2011). O-18/O-16 and V/Cr ratios in gem tsavorites from the Neoproterozoic Mozambique metamorphic belt : a clue towards their origins ?. Mineralium Deposita, 46 (7), p. 671-676. ISSN 0026-4598.
Titre du document
O-18/O-16 and V/Cr ratios in gem tsavorites from the Neoproterozoic Mozambique metamorphic belt : a clue towards their origins ?
Giuliani Gaston, Fallick A. E., Feneyrol J., Ohnenstetter D., Pardieu V., Saul M.
Mineralium Deposita, 2011,
46 (7), p. 671-676 ISSN 0026-4598
The combination of oxygen isotope composition with V-Cr-Mn trace element concentrations of V-bearing garnets (tsavorites) originating from the main deposits of the Neoproterozoic Mozambique Metamorphic Belt is reported for the first time. The database enables the identification of the geological and geographical sources of the main productive areas from northern and southern Tanzania, Kenya, and Madagascar. Three consistent sets of delta O-18 values between 9.5aEuro degrees and 11.0aEuro degrees, 11.6aEuro degrees and 14.5aEuro degrees, and 15.5aEuro degrees and 21.1aEuro degrees have been recognized for primary deposits hosted in graphitic gneisses related to the Neoproterozic metasedimentary series. The delta O-18 value of tsavorite is a good tracer of the environment of its formation; the delta O-18 of the fluid in equilibrium with tsavorite was buffered by the host rock during metamorphism and fluid-rock interaction. This study is a first step in characterizing the geochemistry of gem tsavorite from most of the deposits and occurrences worldwide.