In basalt from Hole 1157A, the fracture + vein density ranges from 3.6 to 25.5/m and averages 13.6/m (Fig. F34). The vein density ranges from 0 to 4.3/m and averages 2.3/m. The calculated volume percent of veins ranges from 0 to 0.05 and averages 0.02. As with cores from Site 1156, fracture + vein density is significantly higher in Core 187-1157A-4R, which is exclusively basalt fragments, as compared with the upper cores from this hole, which are from a basaltic breccia.
Cores from Hole 1157B have more fractures and veins than those from Hole 1157A. The fracture + vein density in basalts from Hole 1157B ranges from 12.0 to 32.3/m and averages 21.3/m (Fig. F34). The vein density ranges from 0 to 19.7 /m and averages 9.0/m. The calculated volume percent of veins ranges from 0 to 1.78 and averages 0.69.