Sample AS-31: Ausable area, Adirondack Mountains, NY

X-ray maps and photomicrographs

by

Frank S. Spear and Jeffrey M. Markussen

email: spearf@rpi.edu

Figure 2 images

Note: in all X-ray images, hot colors indicate higher values

Figure 2. Photomicrograph of pigeonite megacryst from sample AS-31. Note reaction rim of clinopyroxene and orthopyroxene along top margin of crystal and crystals of biotite and hornblende at the margin of the pyroxene cluster. Matrix is plagioclase. Width of field is 17 mm.

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 3 images

Figure 3. Photomicrograph and X-ray composition maps from sample AS-31. Note the core to rim decrease in Al and Fe/(Fe+Mg) and increase in Ca in clinopyroxene and the absence of systematic Fe/(Fe+Mg) zoning in orthopyroxene. Plagioclase shows increase in XAn towards the reaction zone. Field of view in (a) is 4.4 mm.

Photomicrograph detail of metamorphic clino and orthopyroxene on margin of pigeonite


X-ray map: Fe/(Fe+Mg) in clinopyroxene


X-ray map: Fe/(Fe+Mg) in orthopyroxene


X-ray map: Al in clinopyroxene


X-ray map: Ca in clinopyroxene


X-ray map: Xan in plagioclase

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