| Text Description: |
Approximately 15-20’ thick dike that outcrops as rubbly plates and cuts up vertically through silicic material from Dome A as well as flows of unit nA1 at Site 3. Fine grained, holocrystalline, porphyritic with a matrix of cryptocrystalline material, opaque, plagioclase and minor alteration. Plagioclase phenocrysts (An28 - An47, An67) are up to 3.25 mm and are frequently rounded; some have oscillatory zoning; some have patchy, resorbed cores with complex overgrowth rims or resorption embayments. Amphibole phenocrysts are up to 0.5 mm with green-yellow pleochroism. Orthopyroxene phenocrysts are up to 0.5 mm with reddish oxidation? along rims. Opaque phenocrysts up to 0.35 mm. One clinopyroxene phenocrysts, 0.8 mm, was observed. |