Petrographic and geochemical characterization of the Lower Transvaal Supergroup stromatolitic dolostones (Kanye Basin, Botswana)

The dolomite samples from Ramonnedi Formation show Fe and Mn enrichment typical of Precambrian carbonates. Petrographic and geochemical analyses reveal that dolomitization and incipient diagenesis have probably affected the platform carbonates inducing neomorphism and recrystallization (i.e. xenotopic and syntaxial dolomite). The dolomitization processes have mobilized Y giving rise to a near chondritic Y/Ho ratio. Evidences for circulation of hydrothermal fluids related to the intrusion of Moshaneng Igneous Complex and Moshaneng Dolerites are shown only in one sample. Most samples of stromatolitic dolostone have negative Eu anomaly suggesting deposition in a closed basin system restricted from open marine circulation.