Original Mineralogy and Diagenetic Processes of the Soltanieh Formation at Type Section Based on Geochemical Studies

The Soltanieh Formation “Southeast Zanjan”consists mainly of carbonate and shale sequences.Geochemical studies such as Sr/Ca and δ18 O values shows that these carbonates were affected mostly by open system meteoric diagenesis. Distribution of major and minor elements such as Sr/Na and Mn versus Na and δ18 O and δ13 C values of limestones in Soltanieh Formation indicates that the mineralogy of carbonate were originally aragonite. These data fall within the Mozduran limestone and Gordon limestone (Tasmania, Australia) fields due to similar aragonite mineralogy. Original aragonite mineralogy for Neoproterozoic limestones from other parts of the world, has also been suggestedand can support our interpretation. Light δ13 C (-4.57 0/00 VPDB) values in Soltanieh limestone support meteoric diagenesis and Sr/Mn variation indicates high dissolution rate of limestone.Paleotemperature calculations, based on heaviest δ18 O values (-5.830/00 VPDB) and δw of 3 1, range between 23◦ - 31◦c, respectively.