E-plagioclase

Berndt, M.E., Seyfried, W.E. Jr. and Janeckey, D.R. (1989) Plagioclase and epidote buffering of cation ratios in midocean ridge hydrothermal fluids Experimental results in and near the supercritical region. Geochim. Cosmochim. Acta, 53, 2283-2300. 

A further feature of the fit parameters obtained by Blundy and Wood (1994) for plagioclase and clinopyroxene was that the partitioning parabolae become tighter E increases) and displaced to lower as charge increases (Law et al. 2000 Blundy and Dalton 2001). These observations have since been confirmed by a large number of... 

Many minerals are solid solutions (e.g., clays, amphiboles, and plagioclase feldspars). Solid-solution models are either not available or appropriate algorithms have not been incorporated into computer codes. 

Alkali feldspars (K.NajAlSijOg) form a continuous solid solution series at high temperatures, but tend to exsolve upon cooling into a potassium-rich phase and a sodium-rich phase, resulting in perthitic intergrowths (2). Sodic plagioclases and potassium-rich feldspars tend to be studied together, in part because of similarities in structure, composition, occurrence, and weatherability (e.g., 1[). 

In this case, trace element and carrier occupy the same structural position both in the solid phase and in the melt and are subject to the same compositional effects in both phases (i.e., extension of the cation matrix in the melt and amount of anorthite component in the solid). Figure 10.9A shows the effect of normalization the conventional partition coefficient of Sr between plagioclase and liquid varies by about one order of magnitude under equal P-T conditions, with increasing anorthite component in solid solution, whereas normalized distribution coefficient D is virtually unaffected. Figure 10.9B shows the same effect for the Ba-Ca couple. 

Dudas M. I, Schmitt R. A., and Harward M. E. (1971). Trace element partitioning between volcanic plagioclases and dacitic pyroclastic matrix. Earth Planet. Set Letters, 11 440-446. 

Ghent E. D. (1976). Plagioclase-garnet-Al2Si05-quartz A potential geobarometer-geothermometer. Amer. Mineral, 61 710-714. 

Cherniak D.J. and Watson E.B. (1994) A study of strontium diffusion in plagioclase using Rutherford backscattering spectroscopy. Geochim. Cosmochim. Acta 58, 5179-5190. 

Muncill G.E. and Lasaga A.C. (1987) Crystal-growth kinetics of plagioclase in igneous systems one-atmosphere experiments and application of a simplified growth model. Am. Mineral. 72, 299-311. 

Tsuchiyama A. and Takahashi E. (1983) Melting kinetics of a plagioclase feldspar. Contrib. Mineral. Petrol. 84, 345-354. 

---