The effect of elastic strain on the microstructure of free surfaces of stressed minerals in contact with an aqueous solution

Abstract

Abstract. The influence of gradients in bulk elastic strain energy on the dissolution and growth behaviour of minerals in rocks is commonly considered negligible. We experimentally observed, however, that regular arrays of macroscopically visible etch grooves may develop on the originally smooth free surfaces of soluble crystals held in an undersaturated aqueous solution if the crystals are only elastically stressed. These grooves are oriented perpendicular to the compressive stress. They disappear soon after the stress is taken off. The formation of the grooves is well explained by recent theories on the instability of the surface of stressed solids. Development of such instabilities could significantly affect the grain boundary structure in rocks, and have a major effect on dissolution and growth processes.

Microstructural evolution of an incipient fault zone in Opalinus Clay: Insights from an optical and electron microscopic study of ion-beam polished samples from the Main Fault in the Mt-Terri Underground Research Laboratory

“…2 of Ingram et al, 1997). In the samples with widely-spaced shear zones, the surrounding OPA is only weakly deformed, as shown by the cusps in the fossils interpreted to represent minor pressure solution (Den Brok and Morel, 2001). In some other cases, lenses enclosed between shear zones are deformed more homogeneously (Van der Zee and Urai, 2005) to produce gouge.…”

Transient dissolution patterns on stressed crystal surfaces

“…To analyze the dynamic evolution of this instability one has to treat the full nonlinear problem (Yang and Srolovitz, 1993;Müller and Grant, 1999;Kassner et al, 2001). Experiments on rock analog salts in undersaturated solution (den Brok and Morel, 2001) and on stressed aggregates (Zahid, 2001) have shown groove formation as expected from the ATG instability. However, no-one has attempted experimental or theoretical investigation of this phenomenon at fluid saturated conditions pertaining to pressure-solution creep in the Earth's crust.…”

“…This deformation mechanism involves the dissolution of material at sites of relatively high stresses, transport in the fluid and precipitation of material at sites of relatively low stresses (Renard et al, 1999). Recent research has questioned the fundamental mechanisms of this solution-mediated deformation, notably dissolution versus healing at grain contacts (Hickman and Evans, 1992), asymmetric dissolution (Gal and Nur, 1998), dynamics of dissolution in contacts (Dysthe et al, 2002b) and the importance of free-face dissolution (den Brok and Morel, 2001;den Brok et al, 2002). The emerging radical change in our understanding of pressuresolution creep is driven by new experiments and reevaluation of the fundamental theory.…”

Effects of phosphate ions on intergranular pressure solution in calcite: An experimental study

“…One of the most important mechanisms of fluid-rock interaction in upper crustal environments is intergranular pressure solution (IPS) (Weyl, 1959;Paterson, 1973;Rutter, 1976Rutter, , 1983Raj and Chyung, 1981;Raj, 1982;Lehner, 1990Lehner, , 1995Spiers and Brzesowsky, 1993;Dewers and Hajash, 1995;Hickman et al, 1995;Paterson, 1995;Renard et al, 1997;De Meer and Spiers, 1999;Dysthe et al, 2002a,b;Gunderson et al, 2002;Spiers et al, 2004). Intergranular pressure solution is possible in wet rock systems where grain-to-grain contacts are penetrated by water in thin film form or in a nonequilibrium island-channel network (Rutter, 1983;Lehner, 1990Lehner, , 1995denBrok and Morel, 2001;Revil, 2001). It is a coupled chemical-mechanical process involving dissolution of solids within stressed grain contacts and diffusion through the grain boundary fluid into the pores, followed by removal of the dissolved material through longrange transport or by precipitation on low-stress interfaces and free pore walls .…”