Changes

The '''eogenetic substage''' (early diagenetic period) is the time from final deposition to the time when the sediment is buried below the zone of influence from surface processes. The eogenetic zone extends from the surface to the base of the zone of influence of surface processes. Even though the eogenetic substage may be geologically brief and the zone thin, the diagenesis that occurs is more varied and generally more significant than any other substage. Eogenetic processes are generally fabric selective. The major porosity change is reduction through carbonate or evaporite mineral precipitation. Internal sedimentation also reduces porosity. Although minor in comparison, the most important porosity creation process is selective solution of aragonite.<ref name=ch09r10 />

The '''eogenetic substage''' (early diagenetic period) is the time from final deposition to the time when the sediment is buried below the zone of influence from surface processes. The eogenetic zone extends from the surface to the base of the zone of influence of surface processes. Even though the eogenetic substage may be geologically brief and the zone thin, the diagenesis that occurs is more varied and generally more significant than any other substage. Eogenetic processes are generally fabric selective. The major porosity change is reduction through carbonate or evaporite mineral precipitation. Internal sedimentation also reduces porosity. Although minor in comparison, the most important porosity creation process is selective solution of aragonite.<ref name=ch09r10 />

[[file:predicting-reservoir-system-quality-and-performance_fig9-69.png|thumb|{{figure number|2}}Modified. Copyright: Harris et al., 1985; courtesy SEPM.]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-69.png|thumb|{{figure number|2}}Modified. Copyright: Harris et al.,<ref name=Harrisetal>Harris, P. M., C. G. St.-C. Kendall, and I. Lerche, 1985, Carbonate cementation--a brief review, in N. Schneidermann and P. M. Harris, eds., Carbonate CEments :SEPM Special Publication 36, p. 79-95.</ ref> courtesy SEPM.]]

The '''mesogenetic substage''' (middle diagenetic) encompasses the time when the sediment is out of the influence of surface diagenetic processes. Cementation is the major process. [[Porosity]] obliteration occurs when mosaics of coarsely crystalline calcite precipitate in large pores. Pressure solution occurs at higher pressures.

The '''mesogenetic substage''' (middle diagenetic) encompasses the time when the sediment is out of the influence of surface diagenetic processes. Cementation is the major process. [[Porosity]] obliteration occurs when mosaics of coarsely crystalline calcite precipitate in large pores. Pressure solution occurs at higher pressures.