A Comparative study of water fluids of coastal and island mud volcanoes: Acase study of the South Caspian Basin

On a global scale, the South Caspian is a basin where mud volcanoes aremost densely distributed. Numerous active volcanoes are registered here, both onland and in the adjacent sea basin (Caspian Sea), which, as a result of their dailyactivity, discharge water fluids to the Earth's surface.In this work, using samples taken from coastal and island mud volcanoes, acomparative study of the chemical compositions of the fluids expelled from thesalse and gryphon-type emissions, as well as their origin, including thecontribution of various stratigraphic units to the water formation processes.According to our results, the contribution of the condensed waters of theCaspian Sea was greater in the formation of Na-Cl type waters of mud volcanoesin the South Caspian Basin. In addition, the origin of volcanic waters also formedas a result of the contribution of shallow ‘low-mineralized’ pore fluids and deep-seated ‘high-mineralized’ brines correlates well with the depths (1-5.5 km) of theProductive Series strata.