Journal of Geology & Geophysics
Open Access

Micro-Thermometric, Raman spectrometry and bulk Crush-Leach investigation of fluid inclusions in fluorite of Jebel Oust (Zaghouan district, north-eastern Tunisia)

International Conference on Geology

June 22-23, 2015 Florida, USA

Miladi Yasmine1, 2, Bouhlel Salah1, 2, Ahmed Sallemi1, Banks David4, Angels Canals4 and Garnit Hechmi1, 2

Posters-Accepted Abstracts: J Geol Geosci

Abstract :

The Jebel Oust F-Cu deposit in northeastern Tunisia is hosted in Jurassic carbonate. F-Cu mineralization occurs as: (i) Within calcite veinlets; (ii) tectonic brechia at lower Liassic and Upper Jurassic contact and (iii) fractures filling. Fluorite with different habitus occurs as: (i) Large colorless crystals within veinlets crosscutting lower Liassic limestone; (ii) Massive colorless within calcite veinlets crosscutting lower Liassic limestone and upper Jurassic marlstone and (iii) white crystals at lower Liassic and upper Jurassic. Micro-thermometric and Raman bulk Crush-Leach investigation were performed on massive colorless fluorite. Three petrographic types of fluid inclusions have been recognized: Liquid-vapor-solid type (FIAA); liquid-vapor type (FIAB) and vapor type (FIAC). FIAA primary inclusions have homogenization temperatures ranging from 146 to 299°C with a mode 251°C, final melting NaCl temperature range from 246 to 279°C, corresponding to salinities of 34 to 36 wt % NaCl equiv. FIAB primary and pseudo-secondary inclusions have homogenization temperatures ranging from 102 to 196°C and salinities between 3 to 15 wt% NaCl equiv. FIAC inclusions have salinities around 3 wt % NaCl equiv. The semi-quantitative Raman analyses confirmed the presence of water (band stretching at 4120-4180 cm-) and different amounts of CO2 (band stretching at 1250-1400 cm-1). Bulk crush leach analyses show that the solute compositions (Molar ratio Cl/Br= 655) of the fluids trapped in the inclusions hosted in fluorite ratio are consistent with an evaporated seawater origin. Microthermometric, Raman and Crush-Leach fluorite from Jebel Oust have demonstrated represent the involvement of a mixture of halite dissolution water and evaporated seawater component, these results are compatible with Mississippi-Valley- type mineralization and in accordance with the results of (Bouhlel et al., 1988) (Souissi et al., 1996) (30, 5 à 34 Wt% NaCl equiv) and Bouabdellah et al., 2013) at Jebel Tirremi (44, 2 Wt% NaCl+ KCl equiv) at temperatures up to 218°C.