Table T4. Modal proportions for grain mounts of drilling-induced disaggregated gabbro cuttings (Intervals 4–7), Hole U1415I.
| Mineral | 345-U1415I-3R-1, TS 15 | 345-U1415I-3R-1, TS 16 | 345-U1415I-3R-1, TS 17 | |||
|---|---|---|---|---|---|---|
| Modal (%) | Reconstructed igneous mode | Modal (%) | Reconstructed igneous mode | Modal (%) | Reconstructed igneous mode | |
| Plagioclase | 20 | 64.3 | 17 | 57 | 24 | 62.8 |
| Pyroxene | 16 | 31.2 | 16 | 31 | 14 | 30.0 |
| Amphibole after pyroxene | 10 | 12 | 11 | |||
| Polycrystalline amphibole | 2 | 6 | 3 | |||
| Secondary plagioclase | 13 | 13 | 10 | |||
| Zeolite (including veins and plagioclase replacement) | 7 | 3 | 3 | |||
| Cataclasite | 12 | 7 | 12 | |||
| Bruised grain of plagioclase or pyroxene | 2 | 0.6 | 0.8 | |||
| Prehnite vein/Prehnite replacing cataclasite | 5 | 5 | 5 | |||
| Prehnite replacing plagioclase | 3 | 7 | 4 | |||
| Chlorite | 4 | 6 | 5 | |||
| Olivine | 4 | 0.4 | 12 | 7 | ||
| Clay | 1 | 3 | 3 | |||
| Serpentine | 0.2 | |||||
| Sulfide | 0.4 | 0.4 | ||||
| Volcanic clasts | 2 | 0.0 | 3 | 0 | 5 | 0.0 |
|
Cataclastic (excluding volcanics, including prehnite replacing cataclasite) |
20 | 13 | 19 | |||
| Altered | 48 | 58 | 47 | |||
More than 450 points counted in each slide. Igneous mode is estimated according to the following formula: plagioclase = plagioclase + secondary plagioclase + zeolite + prehnite + (cataclasite + bruised grains) × 0.7 + chlorite × 0.8; pyroxene (includes some orthopyroxene) = pyroxene + amphibole after pyroxene + (cataclasite + bruised grains) × 0.3; olivine = olivine + clay minerals + serpentine + polycrystalline amphibole + chlorite × 0.2. The coefficients are derived as follows: cataclasites and bruised grains are assumed to be 70% plagioclase and 30% pyroxene; chlorite is assumed to be 80% replacing plagioclase and 20% replacing olivine; prehnite is assumed to be replacing plagioclase; clay and serpentine are 100% replacing olivine. TS = thin section.
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