Mineralogy, geochemistry, and stable isotope characteristics of barite deposits from Wadi El Mingar, North Eastern Jordan

A barite deposit in the north-eastern part of Jordan was subjected to detailed investigation in order to determine its mineralogy, geochemistry, stable isotopic composition, and genetic model. Barite has fibrous, rosette, and dendritic habits and is hosted in Middle Eocene marine carbonate of the Wadi Shallala Chalk Formation. The barite has an average BaO value of 56 %, and SrO value of 0.40 %. Associated barium-rich limestones have average BaO of 20 % and SrO of 0.22 %. Cr and V are strongly enriched compared to other trace elements, and Sigma REE is low for both the barite and the barium-rich limestone. Chondrite-normalized-REE patterns exhibits LREE enrichment with prominent negative Ce anomalies. For stable isotopes, delta S-34 and delta O-18 range from +24.3 parts per thousand to +28.1 parts per thousand, and +5.22 parts per thousand to +8.75 parts per thousand. Texture, mineral paragenesis, host rock alteration products, relatively high SrO content, high delta S-34, delta O-18 values, and low LREE suggest a hydrothermal origin of the studied barite. These results are comparable to those from hydrothermal barites from Iran in similar host rocks. Structurally, the area is dominated by rift-margin normal faults, which, combined with the presence of impermeable volcanic rocks of the Harrat Ash Shaam Basalt complex, created an upwards moving flow of heated groundwater that mixed with downward-moving seawater along the fault zone. Reaction of oxygen-free hydrothermal fluid carrying Ba and Sr mixing with oxygen-rich seawater carrying SO4 created the deposit. This study proposes that barite deposits formed by the act of hypogene hydrothermal solutions consisting of barium-enriched saline groundwater that percolated through the fractures of Muwaqqar Chalk Marl Formation. These fluids reacted with soft wallrock sediments that are characterised by high organic matter and heavy metals. Ba, along with Cu, Cr, and V and likely Pb and Zn, was dissolved. Sulfur as sulphide may have been transported in these fluids, but the amounts were small based on the highly positive S isotopes in the barite compared to S in the oil shale. Some contribution of magmatic fluid from the adjacent Al Bishriyya volcanic field may have occurred. These basaltic dikes, which are of Pleistocene age, are characterised by a higher concentration of Ba, which reaches 0.14 to 0.19 %, than similar rocks of the basaltic plateau elsewhere in north-eastern Jordan. However, these deposits are basaltic, not a good source of magmatic volatiles, and the oxygen isotopes are too heavy compared to magmatic-sourced water from basalts elsewhere and instead are compatible with barites precipitated from seawater.