TEXTURAL AND MICROANALYSIS OF IGNEOUS ROCKS: TOOLS ...

2.5.2 Measured compositions
2.5.2.1 Major Elements
The interior sections of xenolith crystals have greater An content (An80-An86)
than the xenolith exteriors and phenocrysts, which display a similar range of
An content (An65-An83) (see Table 2.1 and Figs. 2.7,2.8). Phenocrysts from Site
1183 Units 5B, 6, and 7 trend to lower An (An65−73) content than phenocrysts
reported by Sano and Yamashita [123] (An73−78) (Table 2.1). The phenocrysts
contain FeOT, MgO, and Ti within the ranges exhibited by xenolith interiors, but
do however extend to higher abundances of these elements (see Table 2.1). In
Table 2.1 I display representative major and trace element data of both xenolith
crystals and phenocrysts. Note that Ti was measured by EPMA. A spread sheet
of all major element data is available in an online archive.
2.5.2.2 Trace Elements
Selected trace element abundances measured in xenolith crystals and phe-
nocrysts are plotted against mole percent An of plagioclase in Figure 2.7 for sam-
ples from Malaita, Site 1183, and Site 807. With the exception of Eu, a general
negative correlation of element concentration with An content is apparent, which is
a likely result of the greater ease of trace element partitioning into the more elastic
structure of the relatively albite-rich plagioclase (e.g., [10]; Fig. 2.7). Phenocrysts
contain concentrations of La, Ce, and Nd that overlap the ranges exhibited by
xenolith interiors, but extend to higher abundances (see Table 2.1). Xenolith
crystals and phenocrysts contain similar Y and Eu abundances (Fig. 2.7).
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