12. VELOCITIES AND ELASTIC MODULI OF VOLCANIC AND SEDIMENTARY ROCKS RECOVERED ON DSDP LEG 25

On Leg 25 of the Deep Sea Drilling Project five holes penetrated basement, and a total of approximately 12.7 meters of basalt were recovered. We have measured compressional and shear wave velocities to hydrostatic pressures of 6 kb'in representative samples of basalt from each hole and a relatively high density limestone from Site 249. In addition, compressional wave velocities are reported for two sedimentary rocks recovered from Sites 246 and 249. The three basalts studied from Site 249 have intersertal textures with altered feldspar laths and groundmasses higWy weathered to greenish yellow nontronite(?) and brown iddingsite. Weathering appears to decrease slightly with depth, and Sample 249-33-2, 126-129 cm is higWy vesicular. Samples 239-21-1, 46-49 cm and 239-20-1, 125-128 cm are intersertal to felty textured basalts with some alteration of their groundmasses. Basalt Sample 240-7-1, 120-123 cm is similar to the basalts from Site 239 in both texture and alteration. Sample 245-19-1,37-40 cm is a coarse-grained, relatively fresh basalt with an intergranular texture. Alteration is confined to pyroxenes in the groundmass. The two basalts from Site 248 have intersertal textures and contain large (up to 0.7 cm in length) feldspar and subordinate pyroxene phenocrysts. The deeper of the two samples (248-17-2, 122-125 cm) has less alteration and is slightly coarser grained than Sample 248-15-1, 35-38 em. Sample 249-27-2, 133-136 em is a slightly recrystallized biomicrite. Sample 249-28-2, 56-59 cm is a glauconitebearing mudstone, and Sample 246-10, CC (3 cm) is a volcanic sand cemented with carbonate.