Mineralogy, fluid inclusions, and sulfur isotope studies of Ghar Rouban Barite (Pb-Zn) deposit, Western Algeria

Abstract

The Ghar Rouban barite (Pb-Zn) deposit is hosted by the Paleozoic basement and by the Liassic cover. There is no observable cross-cutting relationship between the deposits in the basement rocks and those in the Liassic cover. The main ore types are replacements, open space fillings, breccias, and veins. The thickness and length of the massive barite ore range from 10 cm to 3 m and 60 to 100 m, respectively. The ore minerals include galena, sphalerite, chalcopyrite, barite, quartz, and hematite. In this study, field observations, mineralogical, microthermometric, and sulfur isotope data are used to constrain the possible sources of the ores fluids and the possible age of mineralization. Fluid inclusions from barite reveal homogenization temperatures ranging between 100 and 150°C. Last melting of ice indicates salinities about 19 to 21 wt% equivalent-NaCl, but the low eutectic temperatures indicate that the fluid belongs to NaCl-CaCl2-H2O system. The δ34S values of barite minerals reveal a variation from 21.3 to 29.4‰. The lower values (21.3‰) are recorded in barites hosted by the Hercynian granite. The fluid inclusion compositions suggest that the ore-forming fluid was originally derived from seawater and was mixed with magmatic fluid.