13. PETROCHEMICAL STUDY OF THE BASALTIC BASEMENT OF THE MID-INDIAN

Four of eight holes drilled on Leg 24 encountered basaltic basement, and one other (233A) penetrated through a diabasic sill. The position of these holes is shown on an index map of the northwest Indian Ocean (Figure 1). To date there are 32 chemical analyses (Table 1) for the five holes studied petrographically. These data are sufficient for preliminary petrochemical speculations and for comparison with the chemistry of crestal (oceanic ridge) and continental basalts. At the outset, Table 1 indicates that the basalts contain various amounts of water: from 1.6 to 8.6 weight percent, the latter for a palagonitized breccia, Sample 235-19-2(4). Water content increases during metamorphism and seawater alteration of basalts, and these processes are accompanied by changes in the concentrations of some elements. Har