Sabkha systems of the United Arab Emirates as integrated carbonate–evaporite laboratories: facies architecture, brine evolution, critical-element potential, and geoheritage significance

Abstract

Sabkha systems of the United Arab Emirates (UAE) represent one of the world’s most extensively documented modern carbonate–evaporite settings, yet their multidisciplinary significance has not previously been synthesized within a unified process-based framework. This review integrates sedimentological architecture, hydrogeochemical dynamics, geomicrobiological mediation, radiogeochemical behaviour, and resource-oriented implications across coastal and inland sabkha domains. We demonstrate that UAE sabkhas are not static evaporite flats but highly reactive hydrogeochemical systems characterized by lateral facies zonation, vertical brine stratification, and a fundamental decoupling between water sources and solute inputs. Microbial mat processes and extracellular polymeric substances are shown to play a critical role in early diagenesis, particularly in low-temperature dolomite formation and sulfate–carbonate transformations. Hydrogeochemical synthesis confirms that evaporite mineral assemblages (carbonate → gypsum/anhydrite → halite) reflect recurrent concentration–reset cycles rather than simple linear evaporation paths, with implications for reservoir heterogeneity and early cement distribution. Radiogeochemical partitioning is facies-dependent, controlled by detrital provenance, sulfate mineral trapping, and brine–sediment interaction. While lithium and associated critical elements may concentrate in hydrologically restricted, late-stage residual brines, current evidence supports a cautious, facies-resolved screening approach rather than assumptions of inherent high-grade enrichment. Beyond their value as modern analogues for ancient evaporitic systems and Arabian Plate reservoir–seal models, UAE sabkhas emerge as strategically important geomaterial systems linking sedimentology, basin analysis, geoheritage conservation, environmental baselines, and saline-resource evaluation. This integrated synthesis establishes a framework for evidence-based resource screening and sustainable management of arid coastal evaporitic environments.