Diagenesis indicators

Smith PE, Farquhar RM Hancock RG (1991) Direct radiometric age determination of carbonate diagenesis using U-Pb in secondary calcite. Earth Planet Sci Lett 105 474-491 Spalding RF, Mathews TD (1972) Submerged stalagmites from caves in the Bahamas Indicators of low sea level stand. Quat Res 2 470-472... 

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.

Figure 47. Displacements in composition-temperature space are indicated for the weathering process and diagenesis or epimetamorphism. The simplified system muscovite-pyrophyllite is used to represent these processes in acidic or argillaceous rocks and sediments. I = mica or illite ...

This clearly indicates that pressure plays an important part in the diagenesis of coals, especially of the low rank coals—but in a purely physical sense. Intensely folded coals often contain relatively little moisture (cf. for example Dunningham (3), Edwards (4), Berkowitz and Schein (I). Moreover, we have found that coals encountered in deep wells contain less moisture than coals of similar chemical analyses which have been sampled from mine workings. This may be the effect of the release of pressure on coals exposed in mines, permitting some adsorption of water. 

The redox processes and processes linked to them in the basin sediments can be written in the following or some analogous way. At least some of these processes take place during the early diagenesis, as indicated by the presence of sulfides and iron (II) carbonate in many buried sediments ... 

Meyers, P. A., and Ishiwatari, R. (1993). Lacustrine organic geochemistry—An overview of indicators of organic matter sources and diagenesis in lake sediments. Org. Geochem. 20, 867-900. 

A number of selected molecular parameters obtained from analysis of immature crude oils and sediment extracts are evaluated as indicators of palaeosalinity. The nature of these parameters is discussed taking into account the role of intermolecular and intramolecular incorporation of sulfur into specific functionalized lipids. Specific distribution patterns of methylated chromans and C20 isoprenoid thiophenes and the relative abundance of gammacerane are excellent indicators for palaeosalinity, whilst other parameters such as 14< (H),17a(H)/140(H),170(H) -sterane ratios, the pristane/phytane ratio, the even-over-odd carbon number predominance of n-alkanes and the relative abundance of C35 hopanes and/or hopenes may indicate palaeohypersalinity but are affected by environmental factors other than hypersalinity and by diagenesis. 

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