This study has shown that significant dolomite formation has occurred during early diagenetic stages in the Early Cambrian carbonate sequence of Yorke Peninsula. Relict depositional textures indicate that the sequence consists of tidal flat lithologies in the lower part (Kulpara Formation) and lagoonal lithologies with sporadic bioherms (Koolywurtie Member) in the upper part (Parara Limestone). Early dolomitization was not restricted to the sediments of specific depositional environments, although its intensity is significantly greater in the tidal flat facies and rare to sporadic in the lagoonal facies. Dolomite is mostly replacive, except for a small amount of void-fill cement. Based on crystal size, shape and fabrics, sedimentary structure association and a relative timing of dolomitization, three replacement dolomites and a dolomite cement were recognized in the following paragenetic order : (1) fine crystalline non-planar; (2) medium to coarsely crystalline non-planar; (3) coarsely to very coarsely crystalline mosaics and (4) limpid dolomite cement. The enormous quantity of magnesium required for such regional dolomitization is believed to have been supplied by sea water alone. Petrographic and mineral geochemical (stable isotope and trace element) evidence suggests that dolomitization of the Yorke Peninsula carbonates was an ongoing process during a relatively early diagenetic event, with precipitation from hypersaline water (Type 1 dolomite) followed by a major episode of pervasive recrystallization during shallow burial diagenesis (Type 2 dolomite). The involvement also of hypersaline brine in the formation of Type 2 dolomite is indicated by that stage's association with evaporite minerals. The final stage of dolomitization was marked by the formation of Type 3 replacement dolomite, replacing mainly the previously existing sparry calcite cements. Its xenotopic coarse mosaic fabric and its association with broken ooids suggest that this dolomite was formed during later stages of diagenesis, perhaps under relatively high temperature conditions. Dissolution (by surface-derived meteoric water) probably occurred just after the formation of Type 3 dolomite, and then was followed by the precipitation of limpid dolomite cement. The dolomitization process ceased at sediment burial depths where stylolites began to form.