Role in diagenesis

Burial depth and its attendant temperature-induced chemical reactions played a more important role in diagenesis than whether a formation was deposited in a piggy-back or a foreland basin. 

Kastner, M., Elderfield, H., and Martin, J.B., 1991. fluids in convergent margins what do we know about their composition, origin, role in diagenesis and importance for oceanic chemical fluxes Phil. Trans. R. Soc. London A, 335 243-259. 

The nodules that form at rates on the order of tens of millimeters per million years appear to have been produced primarily by postdepositional remobilization under oxic conditions. These nodules have relatively high copper and nickel contents. The nodules that accrete at the fastest rates (200 mm per million years) appear to have formed primarily via postdepositional remobilization under suboxic conditions. Despite these rapid accretion rates, the suboxic diagenesis -type nodules account for only half of those found in areas where biological productivity is high. The other half appear to have been formed primarily by oxic remobilization. Hydrogenous precipitation appears to play the dominant role in forming only a small percentage of the nodules. 

Diagenesis of Microbially Reduced Sulfur. Postdepositional transformations play an important role in controlling the extent of recycling of microbially reduced S. Pore water profiles from many freshwater systems clearly show that H2S is a short-lived intermediate in sulfate reduction which does not accumulate in sediments (14.16 41-431. However, the conventional paradigm for sulfur diagenesis, in which H2S is initially immobilized by iron monosulfides that later are diagenetically altered to pyrite and elemental S (e.g., 2Q)> does not apply to all freshwater systems. Instead, organic S and CRS (chromium reducible S, which is believed to represent pyrite + S° after preliminary acid distillation to remove AVS), are important initial endproducts of dissimilatoiy reduction. 

Clay mineral diagenesis also may play a role in dolomite formation during burial. The commonly observed conversion of smectites to illite can result in the release of the magnesium necessary for dolomite formation (e.g., McHargue and Price, 1982). Dolomite formation is observed near and within shale beds however, this process again appears to be a localized mechanism and probably is incapable of producing large quantities of dolomite. 

Tectonic events can play a major role in the later history of chalk diagenesis. Subduction and very deep burial can lead to the conversion of calcite to a calc-silicate with release of CO2. As an example, Figure 8.22 illustrates the P-T conditions necessary for the reaction... 

The diagenesis of carbonates in terrigenous sediments requires further research and its role in global cycles assessed. 

Lundegard P. D. (1985) Carbon dioxide and organic acids origins and role in burial diagenesis (Texas Guff Coast Tertiary). Ph.D. thesis. University of Texas at Austin, Austin, Texas, 145pp. 

Makowitz A. and Milliken K. L. (2(X)1) New data on the role of mechanical burial compaction in diagenesis Fro Formation, Gulf of Mexico Basin. Am. Assoc. Petrol. Geologists Ann. Meet, pp. 123-124. 

The study of sulfur diagenesis has a long history. Scientists have long accepted that microorganisms play a major role in geochemical sulfur transformations (Baas Becking, 1925). They also recognized at an earlier time that removal of sulfate occurs in the pore waters of marine mud (Murry, 1895). Subsequent work established that depletion of sulfate from marine pore water is a... 

Morozov A. A. (1995a) Fe and S in the sedimentary process, oxygen-rich Black Sea Zone Part 11. Early sediment diagenesis and its role in Holocene shelf sedimentation. Lithol. Mire Resour. 29(5), 437-448. 

---