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Figure 10.
Figure 11.
Ranges used for classifying grains based on general proportions_
| Shape | AsR | Circularity |
|---|---|---|
| Elongated | >1.6 | n/a |
| Equant | <1.6 | <0.8 |
| Circular | <1.6 | >0.8 |
Ranges for classifying grains based on crystal shape_
| Shape | Convexity |
|---|---|
| Euhedral | >1.8 |
| Subhedral | <1.8 |
| >1.7 | |
| Anhedral | <1.7 |
Ranges for grouping grains based on size_
| Size | Pixels | cm2 |
|---|---|---|
| Coarse | >100,000 | >0.37 |
| Medium | <100,000, >10,000 | <0.37, >0.037 |
| Fine | <10,000 | <0.037 |
Microscope specifications_
| Application | Plan UW |
|---|---|
| Magnification | 2× |
| Numerical aperture | 0.06 |
| Lens image distance/coverslip thickness (mm) | ∞/− |
| Working distance | WD 7.5 |
Calculated extinction angles for biotite grains from sample A14_
| Grain ID | Calculated extinction angle |
|---|---|
| 5242 | 5.5 |
| 5498 | 7.8 |
| 6320 | 4.6 |
| 4302 | 0.7 |
| 6123 | 8.7 |
| 6119 | 6.7 |
| 2414 | 5 |
| 2142 | 1.8 |
| 7255 | 2.3 |
| 1983 | 4.5 |