In situ nanoscale observations of the dissolution of dolomite cleavage surfaces

Experimental calibration of clumped isotope reordering in dolomite

“…The type locality for optical-quality dolomite (Lugli et al, 2000), Eugui dolomite is compositionally homogeneous, near-perfectly stoichiometric, well-ordered, and largely free of structural defects (Barber et al, 1981;Navrotsky and Capobianco, 1987;Reeder and Nakajima, 1982;Reeder and Wenk, 1983). It has been the starting material for a large number of investigations of dolomite crystallinity, thermal stability, deformation and dissolution rates (Barber et al, 1981;Chai and Navrotsky, 1996;Martinez et al, 1996;Reeder and Markgraf, 1986;Urosevic et al, 2012), and a reference standard against which the physical and chemical properties of sedimentary and saddle dolomites are compared (Barber et al, 1985;Jones et al, 2001). Given the paucity of ordered, stochiometric, megacrystic dolomite in nature, and the utility of direct comparison of ∆47 reordering rates to other properties of this well-characterized sample, we suggest that the Eugui dolomite is an appropriate material for these experiments, provided its initial ∆47 composition is sufficiently uniform and resolved from the equilibrium high-temperature limit.…”

Mechanisms influencing micron and nanometer-scale reaction rate patterns during dolostone dissolution

“…In contrast to the relatively large number of studies that have examined minerals that dissolve congruently, the application of in situ imaging techniques to systems exhibiting both primary mineral dissolution and secondary phase precipitation has so far been limited (e.g., Urosevic et al, 2012). Moreover, no such studies have yet explored the behavior of coupled mineral dissolution-precipitation in actual rock samples.…”

“…However, one rock type that reacts much more rapidly, and which could potentially serve as an analogue for other systems, is dolostone. Under mildly acidic conditions dolomite -the dominant mineral comprising dolostone -dissolves (Busenberg and Plummer, 1982;Chou et al, 1989;Gautelier et al, 1999;Pokrovsky et al, 1999;Lüttge et al, 2003) with a nano-scale secondary Mg-rich precipitate, most likely a hydrated magnesium carbonate phase, forming on the surface within minutes of contact with fluid (Urosevic et al, 2012). Thus, dolostone could provide an excellent model for determining the influence of secondary precipitates on the dissolution of primary minerals under laboratory conditions.…”

Characterisation of dolomites before and after reactivity measurement with HCl solution

“…Further details for dolomite dissolution mechanism were presented by Urosevic et al, [21] who demonstrated that (overall) dolomite dissolution rate is controlled by the removal of dolomite layers by spreading and coalescence of shallow etch pits rather than by step retreat from deep pits nucleated at high energy points (dislocations).…”

“…Spreading and coalescence of shallow etch pits (as presented in Ref. [21] ) or dissolution stepwaves [47] are both possible. However, dissolution of sedimentary dolomites seems to be controlled by formation and spreading of deeper etch pits.…”