Frontispiece. A. Core photo of conglomerate from Site 1137 containing rare clasts of garnet-biotite gneiss. Interval 183-1137A-34R-3, 57–80 cm. B. Photomicrographs of garnet gneiss clasts from conglomerate (left) and crystal-vitric tuff (right) at Site 1137 showing poikiloblastic garnet (gt) and biotite (bt). Left: Sample 183-1137A-35R-2, 46–47 cm; field of view = 1.4 mm. Right: Sample 183-1137A-44R-4, 44–46 cm; field of view = 2.8 mm. C. Photomicrograph of crystal-vitric tuff at Site 1137 showing well-preserved cuspate and tricuspate glass shards, which form during explosive fragmentation of vesiculating magma. Sample 183-1137A-44R-4, 44–46 cm. Field of view = 1.40 mm. D. Formation MicroScanner image showing internal structure of a basaltic lava flow (Unit 2) at Site 1137. The horizontal exaggeration is ~4. E. Photomicrograph of spheroidal perlitic fractures in devitrified and altered felsic volcanic glass from Site 1139. Sample 183-1139A-53R-1, 127–130 cm; field of view = 5.5 mm. F. Core photo of highly to completely altered sanidine-phyric trachyandesite from Site 1139. Light gray rock with siderite-filled vesicles is overprinted by white (siderite and quartz) alteration. Quartz, siderite, and hematite(?) vein has prominent oxidation halo that cuts across the white alteration zone. Interval 183-1139A-70R-4, 94–104 cm. G. Core photo of glassy pillow rind at Site 1140 with calcite filling vesicles and veins. Open space-filled dolomite and baked white sediment is along the margin with the glass. Interval 183-1140A-28R-3, 86–101 cm. H. Compositions of volcanic rocks from all Leg 183 basement recovery sites on the Na₂O + K₂O vs. SiO₂ classification diagram of Le Bas et al (1986)¹. For comparison, fields are also indicated for volcanic rocks recovered from Kerguelen Plateau drill sites 738, 747, 748, 749, and 750.

¹Le Bas, M.J., Le Maitre, R.W., Streckeisen, A., and Zanettin, B., 1986. A chemical classification of volcanic rocks based on the total alkali-silica diagram. J. Petrol., 27:745–750.