TY - GEN
T1 - δD and δ18O Values of Halloysite-Kaolinite and Goethite-Hematite in the Fe deposit of Tamra (NW Tunisia): New insights for mixing fluids during ore formation
AU - Dekoninck, Augustin
AU - Vennemann, Torsten
AU - Moussi, Béchir
AU - Jamoussi, Fakher
AU - Hatira, Nouri
AU - Chaftar, R.
AU - Yans, Johan
PY - 2015/8/24
Y1 - 2015/8/24
N2 - The iron mine of Tamra (Nefza District, NW Tunisia) is located within the approximately 50 m thick Zanclean sedimentary series. This sequence contains Fe-Mn oxide impregnation associated with halloysitekaolinite occurrences. Fluid evaporation during weathering and pedogenesis, and/or mixing of surface water and regional hydrothermal fluids are considered to be related to the concentration of iron in those sediments. The stable isotope geochemistry of oxygen and hydrogen of goethite-hematite, and halloysite-kaolinite, was examined in order to provide new insights to the ore formation. The main outcomes of this study indicate that halloysite-kaolinite and goethite did not equilibrate with the same fluid during supergene conditions. In a δD and δ18O diagram, kaolinite from the Tamra deposit plots to the right side of the kaolinite line, which would correspond to unlikely formation temperatures of below 0°C. δD and δ18O values of goethite allow for the same conclusion. The origin of these unusual compositions could be due to two main factors: 1) the arid Zanclean climate with mineral formation from evaporative brines and/or 2) fluid-mineral fractionations with relatively high δ18O hydrothermal fluids.
AB - The iron mine of Tamra (Nefza District, NW Tunisia) is located within the approximately 50 m thick Zanclean sedimentary series. This sequence contains Fe-Mn oxide impregnation associated with halloysitekaolinite occurrences. Fluid evaporation during weathering and pedogenesis, and/or mixing of surface water and regional hydrothermal fluids are considered to be related to the concentration of iron in those sediments. The stable isotope geochemistry of oxygen and hydrogen of goethite-hematite, and halloysite-kaolinite, was examined in order to provide new insights to the ore formation. The main outcomes of this study indicate that halloysite-kaolinite and goethite did not equilibrate with the same fluid during supergene conditions. In a δD and δ18O diagram, kaolinite from the Tamra deposit plots to the right side of the kaolinite line, which would correspond to unlikely formation temperatures of below 0°C. δD and δ18O values of goethite allow for the same conclusion. The origin of these unusual compositions could be due to two main factors: 1) the arid Zanclean climate with mineral formation from evaporative brines and/or 2) fluid-mineral fractionations with relatively high δ18O hydrothermal fluids.
M3 - Conference contribution
VL - 2
SP - 51
BT - δD and δ18O Values of Halloysite-Kaolinite and Goethite-Hematite in the Fe deposit of Tamra (NW Tunisia): New insights for mixing fluids during ore formation
CY - Nancy
T2 - 13th SGA Biennial Meeting
Y2 - 24 July 2015 through 27 August 2015
ER -