Description
- Abstract:
- Thermal evolution of the planet interior is a fundamental problem in Earth and planetary sciences. Geothermobarometers and geospeedometers are powerful tools in studying the thermal history of igneous and metamorphics rocks from the interior of the planets. These tools are developed based on the exchange of elements or isotope ratios of interest between coexisting minerals. The exchange reactions for major elements and partitioning for trace elements with changing temperature (T) and pressure (P) require better understanding of diffusive re-distribution of the elements in the coexisting minerals. Here I conducted numerical simulations of diffusive re-distribution of major and trace elements in cooling and heating bi-mineralic systems using a finite difference method. Applying the diffusion model to the diffusive exchange of REE in two-pyroxene and garnet-clinopyroxene systems, I found that temperatures (TREE) and pressures (PREE) derived from the REE-in-two-mineral thermobarometers (Liang et al., 2013; Sun and Liang, 2015) are essentially the same as the average REE closure temperature and closure pressure defined by the effective partition coefficient following Dodson’s concept of closure temperature (1973, 1976), and are consistent with the prescribed P-T paths (Chapters 1 and 2). Because of the fast diffusion rates of major elements in minerals, diffusion modeling with coupled major elements and REE demonstrates a later closure time of major elements in the bi-mineral systems. The decoupling in closure time between major elements and REE can result in ±20°C uncertainties in REE closure temperatures calculated using the REE-in-two-pyroxene thermometer (Chapter 3). In additional, I have also conducted experimental and theoretical studies of REE partitioning between low-Ca pyroxene and basaltic melts, which is presented in Chapter 4.
- Notes:
- Thesis (Ph.D. -- Brown University (2015)
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Citation
Yao, Lijing,
"Closure Temperature and Closure Pressure in Bi-Mineralic Systems with Applications to REE-in-Two-Mineral Thermobarometers"
(2015).
Earth, Environmental and Planetary Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0H70D6S
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Earth, Environmental and Planetary Sciences Theses and Dissertations
Theses and Dissertations for the Earth, Environmental and Planetary Sciences department....