| Text Description: |
Rubbly outcrop of Dome G at Site 13. Locally reddish color around where the geology map indicates a vent (Lowe et al., 1982). Fine grained, holocrystalline, seriate porphyritic with a matrix of cryptocrystalline material, opaque, feldspar, orthopyroxene? and sparse zircon?. Plagioclase phenocrysts are up to 2.55 mm and both normal and oscillatory zoning are present; grains occasionally display repeated episodes of resorption and overgrowth. Opaque phenocrysts are up to 0.45 mm. Orthopyroxene phenocrysts are up to 0.98 and contain opaque inclusions. Clinopyroxene phenocrysts are up to 0.55 mm. Amphibole phenocrysts are up to 0.6 mm and most have dehydrated to opaque ± pyroxene, but a few cores are present. 90.0% matrix, 9.4% plagioclase, 0.3% orthopyroxene, 0.2% opaque, 0.1% altered phase. |