Photomicrograph of approximately 1/2 of thin section
X-ray map: Xan in plagioclase
X-ray map: Fe/(Fe+Mg) in garnet (red), orthopyroxene (green) and clinopyroxene (blue) (white is oxides)
by
email: spearf@rpi.edu
Figure 7. Sample SAR-1. (a) Photomicrograph showing orthopyroxene megacryst
(center of pyroxene cluster) surrounded by reaction zone of clinopyroxene
+ garnet + plagioclase + quartz. Width of field is 18 mm. Large box shows
location of X-ray maps (b-c); small box shows location of Figure 8. (b)
Fe/(Fe+Mg) composition map showing distribution of oxides + garnet (white),
orthopyroxene (light gray), clinopyroxene (dark gray) and feldspar + quartz
(black). Clinopyroxene occurs both as patches within orthopyroxene megacryst
and along the margins in the reaction zone. (c) Composition map showing
zoning of XAn in plagioclase from high values in the core (XAn = 0.47) to
lower values in the reaction zone (XAn = 0.40).
Photomicrograph of approximately 1/2 of thin section
X-ray map: Xan in plagioclase
X-ray map: Fe/(Fe+Mg) in garnet (red), orthopyroxene (green) and clinopyroxene
(blue) (white is oxides)
Figure 8. Detail of reaction zone from sample SAR-1. (a) Photomicrograph
in partially crossed polars. Some garnet is contained within optically continuous
large plagioclase crystals whereas other garnet is in a polycrystalline
reaction zone. Width of field is 4.7 mm. Box shows location of X-ray maps
(b-e). (b) Fe/(Fe+Mg) distribution in garnet. Garnet at upper left has lower
(darker gray) Fe/(Fe+Mg) than garnet in the reaction zone and the garnet
in the reaction zone is zoned towards higher Fe/(Fe+Mg) on the rim. (c)
Fe/(Fe+Mg) distribution in pyroxene. Clinopyroxene shows symmetrical decrease
in Fe/(Fe+Mg) from core to rim whereas orthopyroxene shows patchy Fe/(Fe+Mg)
zoning. (d) Distribution of Al in clinopyroxene (light gray) and orthopyroxene
(darker gray). Al decreases in each pyroxene from core to rim. (e) Detail
of plagioclase zoning in the reaction zone. XAn decreases from XAn = 46
in the core to XAn = 40 towards the zone, then increases slightly to XAn
= 43 at the contact with pyroxene. Numbers indicate location of analyses
in Table 1. 
Photomicrograph detail of garnet necklace
X-ray map: Fe/(Fe+Mg) in garnet
X-ray map: Fe/(Fe+Mg) in clinopyroxene
X-ray map: Fe/(Fe+Mg) in orthopyroxene
X-ray map: Al in clino and orthopyroxene
X-ray map: Xan in plagioclase
X-ray map: Grossular in garnet
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