The origin of chemically precipitated cements, such as quartz, carbonates, and sulphates, in originally permeable rocks, is related to (1) the mineralogy of the original sediment, which may include both detritus and chemical precipitates; (2) the solubilities of the minerals in dilute to concentrated aqueous solutions in a range of temperatures and pressures; and (3) the composition of interstitial water solutions during various stages of diagenesis. In turn, the composition of these waters may be related to (1) the composition of the original water of the sedimentation environment (if subaqueous) and (2) routes of migration of groundwaters. Changes in interstitial water composition are associated with the successive stages of diagenesis, which can be characterized in ter s of varying degree of depth of burial, with consequent changes of pressure, temperature, and direction of ground-water movement. The actual sequences of cements that have been observed by petrologists can be accounted for by this analysis as well as the referral of particular mineral precipitates to specific diagenetic stages. The reconstruction of the diagenetic stages of a rock's history can be made only if there is a thorough understanding of the geologic history of the particular geologic section and area.

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