Keywords: نسبت عنصر; Lacustrine microbialite; Carbonate geochemistry; Stable isotopes; Salinity; Elemental ratio; Thrombolite; A-MgSi; Mg-Si amorphous phase; A-Si; amorphous silica; CM; clay minerals; cMg; total aqueous concentration of Mg; DIC; dissolved inorganic carbon; OM