Geology and hydrochemistry of brine springs in the Zagros Fold and Thrust Belt (ZFTB), Iran: A review on origin, environmental aspects, and economic potentials

Abstract

The present work is the first regional-scale reconnaissance of 11 brine springs located in the Zagros Fold and Thrust Belt (ZFTB). The springs represent a hypersaline character (Cl− ≥ 20000 mg/L) and emerge in evaporates, marl, and gypsum successions of the Lower Miocene Gachsaran Formation, which is considered as the most important cap-rock of Zagros oil reservoirs. Assessing the hydrochemical features in February and April proved that most of the springs are constantly of Na-Cl type with salinity were probably undergone by the contribution of oil-field related brines. Notably, the presented data indicate that the maximum salt production of springs reaches 173 tons/day, and at least in some of the springs (e.g., Ghale-Madrese 3 and Dobalutan), the Li concentration reaches the threshold for economic extraction from brine processing. Most of the springs discharge into the Karun River, which is considered as an important river in western Iran, providing water for many cities, villages with agricultural projects, and industrial factories. Considering the notable contents of NaCl in most of the studied springs (TDS = ≥42269 mg/L; average 200440 mg/L), the potential for economic lithium recovery, and undesirable environmental effects, especially on quality and water resources ecosystem, attention and consideration of these springs seem to be necessary.