| dc.description.abstract | Consideration of the existing thermodynamic theory of
pressure solution (PS) shows that this theory is applicable to the
development of PS structures as well as to local grain-scale
diffusive transfer. Local precipitation of pressure solved material
ceases when pores are reduced to equilibrium size, if not before by
kinetic considerations. Longer range diffusion may then occur if a
site of non-equilibrium porosity is available. Such porosity may
be generated by particulate flow or by hydraulic fracturing. Long
range diffusion may also depend on greater ease of diffusion, as
may occur along stylolltes.
Measurement of PS strain rates was attempted by stress
relaxation tests (SRTs) at room temperature of both Carrara
marble and compacted aggregates of calcite and quartz sands.
Neither material gave results indicative of PS although strain
rates as low as 10-8.5s-1 were obtained. Work hardening during
loading resulted In alternating increase and decrease of strain
rate concomitant with steadily declining differential stress
during the SRTs. The variation in strain rate, termed cycling, was
interpreted to be the result of non-steady state flow during
loading. Thermal expansion and contraction were shown to be the
cause of pressure fluctuation in a long term quantitative
experiment on PS begun during this study. Such expansion and contraction should be avoided In quantitative studies, particularly
at low strain rates. | |
