Forces and ionic transport between mica surfaces: implications for pressure solution

Structure and properties of loaded silica contacts during pressure solution: impedance spectroscopy measurements under hydrothermal conditions

“…4c). However, they are much higher than the values of *0-5 nm for fluid films between smooth silicate surfaces, determined at room temperature using the surface forces apparatus (e.g., Vigil et al 1994;Alcantar et al 2003). This is perhaps not surprising since little or no surface dissolution is expected during surface forces experiments performed at room temperature.…”

“…Logically, these effects are only significant if the conducting pathway (i.e., the contact) is narrow compared to the thickness of the relevant surface layers. By also assuming values for D i equal to the ionic diffusivities in bulk water, and using concentrations obtained as explained below, an apparent value for d av can be estimated, which, if large enough ([*5 nm) to obviate significant thin film effects on the diffusion coefficient (e.g., Alcantar et al 2003), would justify the bulk diffusivity assumption. In such a case, we can then use d av to go on to estimate the grain boundary diffusivity product Z ¼ Dd av C Ã for total dissolved silica transport.…”

“…Though not addressing actively dissolving interfaces (i.e., interfaces undergoing active pressure solution), various studies have been conducted using the surface forces apparatus (Israelachvili 1986;Horn et al 1989;Vigil et al 1994;Alcantar et al 2003) to study the properties of thin aqueous films bound between solid surfaces at room temperature. Such studies have provided data on fluid film thicknesses, fluid viscosities and hence diffusion coefficients-through the Stokes-Einstein relation (e.g., Israelachvili 1986;Horn et al 1989;Vigil et al 1994).…”

“…Recently, Alcantar et al (2003) used the surface forces apparatus to study interactions between mica surfaces in various electrolyte solutions. At contact normal stresses between 10 and 50 MPa at 21°C, they found fluid film thicknesses between these silicate surfaces ranging from 0 to 3 nm.…”

Sculpting of Rocks by Reactive Fluids

“…For mica systems, disjoining pressures of more than 100 MPa have been measured for films only a few nanometres thick (Alcantar et al, 2003;Anzalone et al, 2006) but for other systems, there is no repulsion at all. In the halite-quartz-H 2 O system, molecular dynamics simulations have recently indicated that the net force between halite and quartz is attractive (because of oppositely charged surfaces).…”