PRESSURE SOLUTION IN SEDIMENTARY BASINS: EFFECT OF TEMPERATURE GRADIENT

Abstract

Pressure solution is an important process in sedimentary basins, and its behaviour depends mainly on the sediment rheology and temperature distribution. The compaction relation of pressure solution is typically assumed to be a viscous one and is often written as a relationship between effective stress and strain rate. A new derivation of viscous compaction relation is formulated based on more realistic boundary conditions at grain contacts. A non-linear diffusion problem with a moving boundary is solved numerically and a simple asymptotic solution is given to compare with numerical simulations. Pressure solution is significantly influenced by the temperature gradient. Porosity reduction due to pressure solution is enhanced in an environment with a higher thermal gradient, while porosity decreases much slowly in the region where the thermal gradient is small. Pressure solution tends to complete more quickly at shallower depths and earlier time in higher temperature environment than that in a low one. These features of pressure solution in porous sediments are analysed using a perturbation method to get a solution for the steady-state. Comparison with real data shows a reasonably very good agreement.