Mechanisms and rates of quartz dissolution in melts in the CMAS (CaO?MgO?Al2O3?SiO2) system

Olivine dissolution in basaltic melt

“…The bent of concentration profiles close to the interface (typically within 10-40 lm of the interface) was commonly attributed to overgrowth of the olivine crystal and resultant diffusion during quench (e.g., Zhang et al, 1989;Shaw, 2004). It cannot be explained by uphill diffusion or by mixed X-ray signal from olivine (e.g., MgO would increase rather than decrease toward the interface if it were due to mixed signal).…”

“…This conclusion is consistent with experimental results of olivine, diopside, spinel, quartz and rutile dissolution in andesitic melt (Zhang et al, 1989), and quartz in haplodacitic melt (Liang, 1999), among others. However, Acosta-Vigil et al (2002) and Shaw (2004) suggested that interface reaction plays a role in corundum and andalusite dissolution in haplogranitic melt, and quartz dissolution in synthetic melts (43-60 wt% SiO 2 ), respectively. Therefore, it is of interest to further address the relative role of interface reaction and diffusion in nonconvective dissolution.…”

“…Crystal growth experiments often involve nucleation and are more complicated than crystal dissolution experiments, hence not suitable for diffusivity measurement. Many authors investigated non-convective dissolution (e.g., Watson, 1982;Zhang et al, 1989;Finnila et al, 1994;Liang, 1999Liang, , 2000Shaw, 2000Shaw, , 2004Shaw, , 2006Morgan et al, 2006). In particular, Shaw (2000) showed experimentally that the dissolution rate of quartz dissolving in basanite melt depends strongly on the mass transfer mechanism.…”

“…Numerous studies on crystal dissolution have been carried out (see Kerr, 1995 for brief reviews of early works; recent works include Shaw et al, 1998;Liang, 1999Liang, , 2000Liang, , 2003Shaw, 2000Shaw, , 2004Shaw, , 2006Acosta-Vigil et al, 2002, 2006Morgan and Liang, 2003;Zhang and Xu, 2003;Morgan et al, 2006). Crystal dissolution in silicate melts can be controlled by interface reaction and mass transfer.…”

Diffusion-controlled melting in granitic systems at 800-900 °C and 100-200 MPa: Temperature and pressure dependence of the minimum diffusivity in granitic melts

“…Once a melt network forms in the rocks, the melt may coalesce and begin to flow owing to buoyancy or accor ding to deviatoric stress, finally forming migmatites or largescale magmatic bodies. Although mechanical mixing is effective in homogenizing granitic magmas during melt segregation and transportation (Brown et al, 1995), the attainment of chemical equilibrium is ultimately governed by diffusion in the melt (Acosta - Vigil et al, 2006a;Shaw, 2000Shaw, , 2004. When local equilibrium is instantaneously established between the melt and the mine rals, diffusion will be the rate -determining process since the reaction being much faster than diffusion (Fisher, 1973(Fisher, , 1978.…”