Table T5. Example of thin section description.
| Thin section: | 301-U1301B-18R-4, 17–19 cm (Piece 1A) | TS # | 33 | Unit: 6 | Observer: MS, RC | ||||
|---|---|---|---|---|---|---|---|---|---|
| Rock name: | Moderately olivine-clinopyroxene-plagioclase-phyric basalt | ||||||||
| Where sampled: | Vein | ||||||||
| Grain size: | Crypto to microcrystalline | ||||||||
| Texture: | Intersertal to intergranular, glomeroporphyritic | ||||||||
|
Primary mineralogy |
Percent present |
Percent original |
Size (mm) |
Approx. comp. |
Morphology | Comments | |||
| Min. | Max. | Av. | |||||||
| Phenocrysts: |
|
|
|
|
|
|
|
|
|
| Plagioclase | 5 | 5 |
|
1.1 | 3.8 | 1.8 |
|
Euhedral to subhedral | Stubby laths and in mono- and polygromeloporphyritic clots. Pale green or brown glass inclusions in the cores of some crystals. |
| Clinopyroxene | 2 | 2 |
|
0.5 | 1.2 | 0.8 |
|
Euhedral to anhedral | Occurs singly, but more frequently in glomeroporphyritic clots or associated with plagioclase laths. |
| Olivine | 0 | 1 |
|
0.8 | 1.2 | 1 |
|
Euhedral to subhedral | Completely replaced by saponite. |
| Groundmass: | |||||||||
| Plagioclase | 55 | 55 |
|
|
<1.1 |
|
|
Euhedral to subhedral | Laths. |
| Clinopyroxene | 20 | 20 |
|
|
<0.5 |
|
|
Euhedral to anhedral | Occurs singly or attached to/intergrown with plagioclase. |
| Olivine | 0 | 12 |
|
|
<0.8 |
|
|
Euhedral to subhedral | Completely replaced by saponite. |
| Secondarymineralogy | Percent |
|
|
Size (mm) |
|
Replacing/filling | Comments | ||
| Min. | Max. | Av. | |||||||
| Saponite | 12 |
|
|
|
|
|
|
Olivine, mesostasis, vein, vesicles | Brown to brown-gray color. |
| Carbonate | 1 |
|
|
|
|
|
|
Vein |
|
| Vesicles/cavities | Percent | Location |
|
Size (mm) |
|
Filling/morphology | Comments | ||
| Min. | Max. | Av. | |||||||
| Vesicles | Tr | Even |
|
0.1 | 0.3 | 0.2 |
|
Saponite |
|
Notes: Veins = 0.05–0.2 mm; anastamosing saponite and carbonate veins. These microveins cut through crystals, or "step" around them. Carbonate does not occur along the entire length of the vein. Carbonate forms a fibrous central vein fill suggesting it formed after the saponite. Approx. comp. = approximate composition, Min. = minimum, Max. = maximum, Av. = average, Tr = trace. Only a portion of this table appears here.
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