Burial History and Diagenetic Reaction Kinetics

Abstract

Relations among burial histories deduced from stratigraphy, thermal regimes imposed by tectonics and sedimentation, and rates of diagenetic reactions extrapolated from experimental data have been explored by using sedimentation diagrams, plots of burial with respect to the sediment-water or sediment-air interface as a function of time elapsed since deposition. One can estimate paleogeotherms from such plots, using assumptions on heat flow, thermal conductivities, compaction and cementation effects on porosity, and convecting formation water systems. From these, one can deduce the temperature history of a sediment as a function of postdepositional time. That history can be converted to the integrated value of temperature as a function of time. This value, which takes into ccount the total contribution of time and temperature, is the relevant parameter for reaction kinetics. A plot of the time-temperature integral versus postdepositional time for a given formation can then be compared with the time-temperature integral for specific yields of a diagenetic reaction to deduce at what stage in its history a sediment would have accumulated sufficient time and thermal energy to accomplish a given extent of reaction. These deductions can be compared with petrologic information on the time of origin of diagenetic phases.