T237 Tick Tock in the Rock: Elucidating the Time Scales of Geologic Processes and Honoring the Contributions of Bruce Watson, 2018 Roebling Medalist

Wednesday, 7 November 2018
8:00 AM - 12:00 PM
Room 240-241

KINETICS OF MINERAL DISSOLUTION: ROLE OF INTERFACE REACTION, DIFFUSION, AND CONVECTION, AND DEALING WITH DIFFUSION OF ALL COMPONENTS

Paper number: T237-5
Program: Technical Sessions
Time: 8:55 AM – 9:10 AM

Authors

Abstract

Mineral dissolution plays a key role in magma contamination and evolution. Watson (1982) and Harrison and Watson (1983) were the first to experimentally quantify the rate of and diffusion behaviors during mineral dissolution, including the presence of uphill diffusion. The works opened up numerous follow-up studies. This presentation will review our work on the kinetics of mineral dissolution, with emphasis on recent progresses on (i) dealing with diffusion of all components and (ii) estimating dissolution rates for concentration-dependent diffusivity. (1) Distinguishing convective and diffusive mineral dissolution and evaluating the role of interface reaction (Zhang et al., 1989); (2) Developing a modified effective binary diffusion treatment to empirically fit the uphill diffusion profiles (Zhang, 1994) using the concept of quasi-equilibrium of two-liquid partitioning, first advanced by Watson (1982); (3) Expanding the empirical theory on convective mineral dissolution (Zhang and Xu, 2003, 2008; Zhang, 2006) after Kerr (1995) introduced the theory to geology; (4) Obtaining diffusive mineral dissolution data (Zhang et al., 1989; Chen and Guo, 2008, 2009; Yang et al., 2016; Yu et al., 2016; Zhang and Xu, 2016); (5) Quantifying and predicting the full multicomponent diffusion profiles (Guo and Zhang, 2016, 2018) using diffusion matrices extracted from various experimental data in basaltic melts. The treatment is now able to predict most diffusion features during mineral dissolution. (6) Formulating a method to estimate diffusive mineral dissolution rate when the diffusivity of the principal equilibrium-determining component depends on melt composition either linearly or exponentially (Zhang, 2018).

1. Watson (1982) CMP, 80, 73; 2. Harrison, Watson (1983) CMP, 84, 66; 3. Zhang, Walker, Lesher (1989) CMP, 102, 492; 4. Zhang (1994) JGR, 98, 11901; 5. Kerr (1995) CMP, 121, 237; 6. Zhang and Xu (2003) EPSL, 213, 133; 7. Zhang (2006) Env. Sci. Tech., 40, 3655; 8. Zhang and Xu (2008) Elements, 4, 47; 9. Chen and Zhang (2008) GCA, 72, 4756; 10. Chen and Zhang (2009) GCA, 73, 5730; 11. Yang et al. (2016) Chem. Geol., 441, 162; 12. Yu et al. (2016) GCA, 179, 257; 13. Zhang and Xu (2016) Am. Mineral., 101, 1252; 14. Guo and Zhang (2016) GCA, 195, 126; 15. Guo and Zhang (2018) GCA, 228, 190; 16. Zhang (2018) Goldschmidt Conf Abstr.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-319568

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