EPMA IMAGES

The attached images and mineral data can be used to supplement an instrument-based lab,or serve as the basis for lab that can be completed without an instrument. Please providecredit for the images as given.

Figure 1. Principal beam-sample interactions. (a) Electron phenomena resulting from animpinging beam of electrons on a flat sample. (b) Electron-sample interactions within the“interaction volume”, whose size depends on beam energy and sample characteristics(primarily average atomic number, or atomic density).

Additional diagrams to illustrate the schematics of a microprobe or SEM, ionizationphenomena, electron shell structure, etc., can be found in Goldstein et al. (1992).

Figure 2. Secondary electron (SE) images. (a) Fossil diatoms. (b) Galena (PbS) crystals.Images courtesy Ellery Frahm, University of Minnesota Microprobe Lab.

Figure 3. Back-scattered electron (BSE) image of sample of pelitic schist fromAntarctica. Field of view is approximately 5 mm. In general, brighter minerals havehigher mean Z (where Z is atomic number).

Figure 4. X-ray composition maps collected by rastering the electron beam over an areaof devitrified volcanic glass. BSE image (upper left) shows overall compositionalvariation as differences in mean Z. Remaining images show relative abundances ofspecific elements. Brighter areas reflect higher concentration. Images courtesy ElleryFrahm, University of Minnesota Microprobe Lab.

Figure 5. X-ray composition maps of plagioclase phenocrysts in volcanic glass, showingoscillatory growth zonation. Images courtesy Ellery Frahm, University of MinnesotaMicroprobe Lab.

Figure 6. X-ray composition maps of phenocrysts in volcanic glass, intergrown withmagnetite grains. Images courtesy Ellery Frahm, University of Minnesota MicroprobeLab.

Figure 7. Thin section photomicrographs of sample 89GGR-33A, a pelitic schist fromthe Ross orogen, Transantarctic Mountains, Antarctica. Field of view is approximately 8mm.

Figure 8. Back-scattered electron image map of a section of sample 89GGR-33A.Numbered circles correspond to spot locations where EDS spectra were collected.

Figure 9. Energy-dispersive spectra of spot mineral analyses in sample 89GGR-33A forlocations 1-5 in Figure 8.

Figure 10. Energy-dispersive spectra of spot mineral analyses in sample 89GGR-33A forlocations 6-10 in Figure 8.

Figure 11. Back-scattered and element composition maps for Area B of sample 89GGR-33A.

Figure 12. Element composition maps for Area C of sample 89GGR-33A.

Figure 13. Thin section photomicrographs of sample 89GGR-33B, an amphibolite fromthe Ross orogen, Transantarctic Mountains, Antarctica. Field of view is approximately 5mm.

Figure 14. Back-scattered and element composition maps for a section of sample89GGR-33B shown in Figure 13.

Figure 15. Energy-dispersive spectra of spot mineral analyses in sample 89GGR-33B forlocations 1-4 in Figure 14.

ELECTRON PROBE ANALYSES

Mineral #1

SiO2 36.54TiO2 0.03Al2O3 20.76MgO 3.39CaO 1.22MnO 0.41∑Fe as FeO 37.69Na2O 0.03K2O 0.01

Mineral #5

SiO2 33.13TiO2 3.48Al2O3 17.73MgO 5.95CaO 0.02MnO 0.01∑Fe as FeO 23.93Na2O 0.13K2O 9.09

incident electron beam

characteristic X-rays

characteristic X-rays

Bremsstrahlung X-rays

Bremsstrahlung X-rays

visible light (cathodoluminescence)

secondary fluorescence

heat

back-scattered e's

back-scattered e's

secondary e's

secondary e's

Auger e's

Auger e's

transmitted e's

sample

sample

diffracted e's

electroninteraction

volume

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Figure 1. Principal beam-sample interactions. (a) Electron phenomena resulting from an impinging beam of electrons on a flat sample. (b) Electron-sample interactions within the “interaction volume”, whose size depends on beam energy and sample characteristics

a

b

University of Minnesota microprobe lab (Analyst: Ellery Frahm)

University of Minnesota microprobe lab (Analyst: Ellery Frahm)

SECONDARY ELECTRON (SE) IMAGES

Figure 2. Secondary electron (SE) images. (a) Fossil diatoms. (b) Galena (PbS) crystals. Images courtesy Ellery Frahm, University of Minnesota Microprobe Lab.

a

b

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BACK-SCATTERED ELECTRON (BSE) IMAGE

Mg

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Figure 3. Back-scattered electron (BSE) image of sample of pelitic schist from Antarctica. Field of view is approximately 5 mm. In general, brighter minerals have higher mean Z (where Z is atomic number).

University of Minnesota microprobe lab (Analyst: Ellery Frahm)

X-ray COMPOSITION MAPS

BSE Al

Ca Fe

Mg Si

Figure 4. X-ray composition maps collected by rastering the electron beam over an area of devitrified volcanic glass. BSE image (upper left) shows overall compositional variation as differences in mean Z. Remaining images show relative abundances of specific elements. Brighter areas reflect higher concentration.

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University of Minnesota microprobe lab (Analyst: Ellery Frahm)

X-ray COMPOSITION MAPS

Figure 5. X-ray composition maps of plagioclase phenocrysts in volcanic glass, showing oscillatory growth zonation.

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University of Minnesota microprobe lab (Analyst: Ellery Frahm)

X-ray COMPOSITION MAPS

Al Si

Mg Fe

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Figure 6. X-ray composition maps of phenocrysts in volcanic glass, intergrown with magnetite grains.

89GGR-33A

Plane-polarized light

Crossed-polarized light

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Figure 7. Thin section photomicrographs of sample 89GGR-33A, a pelitic schist from the Ross orogen, Transantarctic Mountains, Antarctica. Field of view is approximately 8 mm.

1

6

210

8

7

9

5

4

3

A B

C D

89GGR-33A: BSE map

1 mm

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Figure 8. Back-scattered electron image map of a section of sample 89GGR-33A. Numbered circles correspond to spot locations where EDS spectra were collected.

1

2

3

4

5

Co

un

ts

Energy (keV)

89GGR-33A

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Figure 9. Energy-dispersive spectra of spot mineral analyses in sample 89GGR-33A for locations 1-5 in Figure 8.

6

7

8

9

10

Co

un

ts

Energy (keV)

89GGR-33A

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Figure 10. Energy-dispersive spectra of spot mineral analyses in sample 89GGR-33A for locations 6-10 in Figure 8.

Fe

Si

CaAl

Ti

BSE

89GGR-33A (Area B)

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Figure 11. Back-scattered and element composition maps for Area B of sample 89GGR-33A.

Ca

Al

KMg

Na

Si

89GGR-33A (Area C)

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Figure 12. Element composition maps for Area C of sample 89GGR-33A.

689GGR-33B

Plane-polarized light

Crossed-polarized light

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Figure 13. Thin section photomicrographs of sample 89GGR-33B, an amphibolite from the Ross orogen, Transantarctic Mountains, Antarctica. Field of view is approximately 5 mm.

Si

Mg Fe

CaAl

BSE

1

2

3

4

89GGR-33B

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Figure 14. Back-scattered and element composition maps for a section of sample 89GGR-33B shown in Figure 13.

2

1

4

3Co

un

ts

Energy (keV)

89GGR-33B

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Figure 15. Energy-dispersive spectra of spot mineral analyses in sample 89GGR-33B for locations 1-4 in Figure 14.