Isotopic analysis, hydrogeochemistry and geothermometry of Tang-Bijar oilfield springs, Zagros region, Iran

Abstract This study is focused on warm and cold springs in Tang-Bijar oilfield of southern Iran. The springs emerge from fractures and faultlines within the carbonate and evaporitic rocks of Zagros Thrust Belt (ZTB) and vary in temperature between 20 and 44 °C. Chemical analyses define three main chemical water associations reflecting different hydrochemical processes including: (1) Ca-HCO 3 ,(2) Mg-SO 4 and (3) Na-Cl. Based on isotope analysis, meteoric water is the origin of these spring waters. Two distinct hydrogeological systems are postulated: a deep moderate-temperature (40 to 45 C) geothermal system recharged by meteoric waters mixed with oilfield brine and a shallow cold aquifer system related to local groundwater.