Diagenesis in marine sediments

Schematic diagram of the coupled iron and phosphate cycles during early diagenesis in marine sediments. Light gray ovals and circles represent solid phases black arrows are solid-phase fluxes. White outlined black arrows Indicate reactions white arrows are diffusion pathways. Source From Ruttenberg, K. C. (2003). Treatise on Geochemistry, Elsevier Ltd. pp. 585-643.

Degens, E. T. and Mopper, K. (1976). Factors controlling the distribution and early diagenesis of organic material in marine sediments. In "Chemical Oceanography" (J. P. Riley, ed.), Vol. 6, pp. 59-113. Academic Press, New York. 

Measurements of radionuclides and metals in marine sediments and particulate matter are conducted for a variety of purposes, including the determination of sedimentation rates, trace metal and radionuclide fluxes through the water column, enrichment of metals in specific phases of the sediments, and examination of new sedimentary phases produced after sediment deposition. Such studies address fundamental questions concerning the chronology of deep-sea and near-shore sedimentary deposits, removal mechanisms and cycling of metals in the ocean, and diagenesis within deep-sea sediments. 

Formation of Pyrite. Iron is carried to the peat swamp, before seawater transgression, as ferric oxide and hydroxides adsorbed on fluvial clays (123). During early diagenesis in a reducing environment, ferric iron is reduced to ferrous, which reacts with hydrogen sulfide to form iron monosulfide. If the basic mechanism of pyrite formation is similar to that in marine sediments... 

Keil, R.G., Tsamakis, E., Hedges, J.I. (2000) Early diagenesis or particulate amino acids in marine sediments. In Perspectives in Amino Acid and Protein Chemistry (Goodfriend, G.A., Collins, M.J., Fogel., M.L., Macko, S.A., and Wehmiller, J.F., eds.), pp. 69-82, Oxford University Press, New York. 

In recent years various workers f1-7J have successfully developed models based on the mathematics of diffusion (8) to describe vertical profiles of selected chemical parameters in marine sediments dominated by sulfate reduction. Several papers 9, 10) have also proposed models for nitrogen diagenesis in the upper aerobic zone of such sediments. Most of these models, however, deal with only one or two relatively well behaved parameters, such as SO5" or CO2, which do not interact strongly with other components of the sediment besides organic matter. A truly comprehensive model for such sediment should deal simultaneously with all of the major chemical parameters of the system and ideally should be formulated as an initial value prob-... 

Although the above discussion does not constitute a rigorous verification of the model (21), the similarity of the simulations presented here to observed profiles of H2S, FeS and FeS2 in marine sediments indicates that the model may be of value in the study and interpretation of vertical patterns in sulfur diagenesis. Comprehensive multiparameter analyses of sediment profiles from a variety of sites will be required to validate the model. In this endeavor techniques will have to be devised to ascertain the molar surface areas of the various solid phase reactants. Eventually it may be possible to expand the model presented here to include processes in the aerobic zone so that the depth to the oxidized-reduced boundary can be predicted as well as the pH profile through this boundary. This achievement would constitute a truly compr ensive model. 

Ruttenberg, K. C. 1990. Diagenesis and burial of phosphorus in marine sediments Implications for the marine phosphoms budget. Ph.D. Dissertation, Yale University, New Haven, CT, pp. 375. 

Tromp T. K., Cappellen P. V., and Key R. M. (1995) A global model for the early diagenesis of organic carbon and organic phosphorus in marine sediments. Geochim. Cosmochim. Acta 59, 1259-1284. 

Henrichs S. M. (1992) Early diagenesis of organic matter in marine sediments progress and perplexity. Mar. Chem. 39, 119-149. 

Van Cappellen P. and Berner R. A. (1988) A mathematical model for the early diagenesis of phosphorus and fluorine in marine sediments apatite precipitation. Am. J. Sci. 288, 289-333. 

Calvert, S.E., 1974. Deposition and diagenesis of silica in marine sediments. In K.J. Hsii and H.C. Jenkyns (Editors), Pelagic Sediments on Land and Under the Sea. Interna-... 

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