Distribution plagioclase

Figure 5.15 Distribution of spallogenic 38Ar in plagioclase crystals from the lunar anorthosite 15415 analyzed by Turner (1972). A population of spherical grains with uniform grain size is assumed. The t( values were deduced from the diffusion of 37Ar (Albarede, 1978).

Figure 5,62 Experimentally observed distribution of NaAlSi30g component between plagioclases and alkaline feldspars (Seek, 1971) compared with results of Wohl s and Kohler s models. Reproduced from Barron (1976), with modifications.

B) Plagioclase/matrix distribution, data of Dudas et al. (1971), Ewart and Taylor... 

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. 

Figure 10,9 Effect of normalization on trace element distribution of Sr (A) and Ba (B) between plagioclase and silicate liquid. Distribution curves are based on various experimental evidence (Ewart et al., 1968 Ewart and Taylor, 1969 Berlin and Henderson, 1968 Carmichael and McDonald, 1961 Philpotts and Schnetzler, 1970 Drake and Weill, 1975). Ab albite Or orthoclase An anorthite.

Kotelnikov A. R., Bychkov A. M., and Chernavina N. I. (1981). Experimental stndy of calcium distribution in granitoid plagioclase and water-salt fluid at 700°C and Pn = 1000 atm. 

After the experiments, significant quantities of newly formed minerals were observed at the cold extremity of the tube, pointing to a fast material transport by diffusion from the hot to the cold end of the tube. The following spatial distribution of newly formed phases, reflecting the temperature profile, was observed in both runs (Fig. 8) quartz + K-feldspar + plagioclase + Mg-rich saponites (hot extremity) quartz + K-feldspar + plagioclase (middle of the tube) and alkaline or Ca-rich clays + quartz + plagioclase (cold extremity). The cation composition of the phyllosilicates was similar in both experiments. Some newly fonned quartz crystals... 

Figure 8.8. Crystal size distribution (CSD) plots of (a) plagioclase in igneous rock and (b) garnet porphyroblast in contact metamorphic rock [4].

Intact soil cores (6.7 cm i.d.) were taken with spilt spoon at depths of 1 to 2 meters from a field test site located approximately 50 km east of Cincinnati, Ohio. The soil in this interval consists mainly of quartz (60%) and clay minerals (35%) with minor amounts of plagioclase and potassium feldspar. The majority of clay is illite and smectite, with minor amount of kaolinite. Soil chemical properties were analyzed prior to, and after, electroosmosis, in order to evaluate the effects of electroosmosis on the distribution of elements within the soil column. Sampled cores were wrapped in aluminum foil and stored at 12°C until the EO cell was assembled. 

Figure 17 Relative distributions of 11 elements (normalized to 29Si) across the 11-mm distance. Visual inspection under a microscope supports the distributions suggested in the plot. Laser shots on the lava matrix occurred at 0, 1,4, 5, 6, and 9 mm, whereas laser shots on the plagioclase crystals occurred at 2, 3, 7, 8, 10, and 11 mm. (From Ref. 29.)...

Figure 3. The result of X-ray mapping which shows the U(V1) distribution on granite surface. (Ksp K-feldspar, PI Plagioclase, Qz Quartz, Q Chlorite)...

Drake M. J. (1972) The distribution of major and trace elements between plagioclase feldspar and magmatic silicate liquid an experimental study. PhD Thesis, University of Oregon Eugene, Oregon, USA (unpublished). 

Plagioclase microlite size distributions have been attributed to largely syn-eruptive crystallization, as illustrated by the rhyolitic groundmasses of Merapi (Hammer et al., 2000), Mt. St. Helens (Cashman, 1992 Geschwind and Rutherford, 1995), and Pinatubo (Hammer et al.,... 

Resmini R. G. and Marsh B. D. (1995) Steady-state volcanism, paleoeffusion rates, and magma system volume inferred from plagioclase crystal size distributions in mafic lavas Dome Mountain, Nevada. J. Volcanol. Geotherm. Res. 68, 273-296. 

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