| Text Description: |
A 4-5' thick, platy dike trending N25E that intrudes silicic rubble from Dome A near Site 5. Further up in the section, the dike flattens out to become a sill that intrudes into a lahar/pyroclastic flow package at Site 5. There is no bake zone with the lahar/pyroclastic flow. The sill then twists up vertically cutting through blocky autobrecciated? flows. Fine-grained, holocrystalline, intergranular, seriate porphyritic with matrix of mesostasis, red alteration patches, opaque, plagioclase and clinopyroxene. Plagioclase phenocrysts (An17-An49) are up to 1.8 mm and most large grains have sieve textured intermediate zones, complex zoning, and a few include orthopyroxene and matrix along rim. Orthopyroxene phenocrysts are up to 1.0 mm and display thick clinopyroxene rims, opaque and melt inclusions, and several have resorbed edges. |