Burial diagenesis alteration

Burial diagenesis and subsequent alteration of chalk The Overall Diagenetic Pathway... 

The principles of pH buffering can be used to understand the evolution of pH and CO2 and thus the mineral alteration that takes place during the burial diagenesis of sediments (cf. Hutcheon etal. 1993). 

Diagenesis and catagenesis can alter the evaporite minerals after burial. For example, high temperatures, pressures, and pore-water salinities characteristic of deep burial lead to the conversion of gypsum into anhydrite. Thus, evaporite mineralogy reflects not only the environmental conditions under which the evaporite was formed, but also those under which diagenesis and catagenesis occurred. 

The effects of wind winnowing by bottom currents could also explain why 25% of the nodules are buried in the sediments. Variations in local rates of sediment deposition and erosion could cause the periodic burial and exposure of nodules. Growth would be expected only during periods of exposure. This would also explain why buried nodules appear unaffected by diagenesis (i.e., they are not buried long enough to undergo extensive alteration). 

Pollard Jr., C.O., 1971. Semidisplacive mechanism for diagenetic alteration of montmorillonite layers to illite layers. Appendix in C.E. Weaver and K.C. Beck, Clay-water diagenesis during burial how mud becomes gneiss. Geol. Soc. Am., Spec. Pap., 134 79-93. 

Diagenesis processes that alter the structure, texture, and mineralogy of a sediment, turning it progressively into solid hard rock early diagenesis occurs immediately after deposition or burial of the sediment. 

Clay Minerals. Clay minerals may be transported into the swamp during peat accumulation (detrital), precipitate from solutions rich in aluminum, silicon and various cations (syngenetic and epigenetic), or may form by the alteration of other minerals either within the swamp or during burial (transformation and/or diagenesis) (6). 

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