Abstarct: Travertine covers a vast area in the southwest of Azarshahr (East Azarbaijan province), in some parts there are currently active springs which depositing travertine. According to field studies, there are three types of morphology including Fissure-Ridges, Mounds and Cascades in these travertines. Field studies also detected three types of travertine lithofacies including crystalline crust, coated gas bubbles, and calcite rafts as well as two types of tufa lithofacies including bacterial microherm and phythoherm frxamestone. Thin-section studies, SEM images and XRD analysis have been used to detect peloidal, thrombolytic, dendritic and spary calcite fabrics. These studies also detect minerals such as calcite, aragonite and quartz in most of the samples, however the dominant phase in all samples are calcite. Hydrochemical studies have shown that, in terms of acidity, water sources are neutral; their EC values are higher than the drinking water standard and the type of water travertine springs is from biocarbonate region. The origin of the main ions in spring water is also the dissolution of carbonates and to some extent evaporites. The isotopic studies indicate the meteoric source for the springs. The amount of iron, sodium, and potassium elements in travertine deposits clearly emphasizes their thermogenic nature. The amounts of strontium, barium and beryllium also indicate the thermogenesis and calcareous, evaporative or dolomite origin. The depleted oxygen isotope (δ18O) and enriched carbon isotope (δ13C) is also indicator of thermogenic source, and carbonate or igneous source rocks for these deposits. baxsed on these studies, it seems that hydrothermal fluids may have initially taken the CO2-derived from magma, and during the upward movement with carbonate rocks, decarbonization has been made. These fluids transport CO2 from carbonates, and then they appear as spring’s water at the surface and precipitate as travertine due to the rapid release of CO2.