The diagenetic carbonate minerals include dolomite, siderite, and calcite.
Dolomite occurs as disseminated rhombs and cemented beds and nodules.
Disseminated dolomite rhombs up to 10 m in diameter are currently forming in the uppermost 200 m of sediment as indicated by the exponential decrease in pore-water Mg and Ca. Organic matter degradation by way of sulfate reduction promotes precipitation of dolomite by removing sulfate ion and increasing the carbonate alkalinity. The availability of precursor carbonate and variations in sedimentation rate related to sea-level fluctuations appear to be the primary factors that determine the abundance and mineralogy of the diagenetic carbonates.