Compaction creep of quartz-muscovite mixtures at 500°C: Preliminary results on the influence of muscovite on pressure solution

Abstract

Abstract It is widely claimed that the presence of phyllosilicates in sandstones increases intergranular pressure solution (IPS) rates in these rocks. However, this has not been experimentally confirmed. This study reports the results of isostatic hot-pressing compaction experiments at a temperature of 500°C and an effective pressure of 100 MPa on mixtures of quartz and muscovite. Previous work has shown that under these conditions dissolution is rate controlling in pure quartz. No acceleration of compaction rates of quartz by the addition of muscovite was observed. Instead, a modest decrease in compaction rates was observed (factor 3–10), which we infer was due to a decrease in IPS rate. The effect of muscovite in slowing IPS may be due to the influence of dissolved aluminum (Al 3+ ) dominating over any accelerating effects of alkali-metal cations. From the geochemical literature, Al 3+ in solution is expected to decrease the solubility, dissolution rates and precipitation rates of quartz. However, the effect of the addition of muscovite on IPS rates in quartz when controlled by diffusion or precipitation may be different. Experiments should be conducted on quartz sand under conditions where diffusion or precipitation is rate controlling to investigate these possible effects.