Abstract In Iran, almost all major travertine deposits with
NW–SE trend are exposed in Urumieh-Dokhtar volcanoplutonic
belt. In this study, morphology of travertine,
source of CO2, and classification of travertine were
investigated using geochemistry of carbon dioxide,
stable carbon and oxygen isotopic analysis, SEM images
and thin sections. Morphology of travertine in the study
area includes mound and cascade. Stable carbon and oxygen
isotope values of the north Urumieh-Dokhtar volcanoplutonic
belt travertines range between 1.46 and 11.71%
(VPDB) and - 6.08 and - 10.21% (VPDB), respectively.
The high d13C values suggest a contribution of CO2 liberated
by thermometamorphic decarbonation besides its
magmatic origin. Consequently, these travertines are classified
as belonging to the thermogene category. A probable
reason for the observed high carbon isotope composition in
these deposits may be CO2 consumption as suggested by
the presence of bacteria and diatom activities, verified by
SEM images. Pisoid, crystalline crust and pebbly lithofacies
were observed. The stable isotope compositions were
compared to travertines around the world. Similarities in
lithofacies and morphology exist between northern Urumieh-
Dokhtar volcano-plutonic belt and travertines of
Turkey and Spain. The Iranian travertines are located in
areas with volcanic activity. Obviously, the geothermal
system remained active throughout the late Quaternary to
present.