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indicate that two of the inferred key characteristics of kimberlitic magmas - low sodium and
high water contents (Fig. 5; Kjarsgaard et al., 2009) - unambiguously relate to postmagmatic
alteration that affected most kimberlites worldwide.
(b)
(a)
0.5 mm
0.5 mm
(c)
(d)
0.1 mm
0.1 mm
Fig. 3. Photomicrographs in plane-polarised light of individual crystals of olivine-I (a, b) and
olivine-II (c, d) showing networks of magmatic inclusions, including crystal, fluid and
carbonate-chloride melt inclusions.
3. Kimberlite olivine: Morphology and composition
Two populations of olivine in the Udachnaya-East kimberlite can be recognised based on
size, colour, morphology, and entrapped inclusions. Consistent with many other studies of
kimberlitic olivine (e.g., Boyd & Clement, 1977; Emeleus & Andrews, 1975; Hunter & Taylor,
1984; Mitchell, 1973; Mitchell, 1978; Nielsen & Jensen, 2005; Sobolev et al., 1989) the
populations are represented by olivine-I (interpreted by different workers as cognate
phenocrysts or xenocrysts) and groundmass olivine-II. However, as it follows from Arndt et
al. (2010), Brett et al. (2009) and Kamenetsky et al. (2008) both populations significantly
overlap in terms of composition, and possibly origin.
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