Sea water-basalt interaction in the Kerguelen Plateau, Indian Ocean

All studied basalts from Hole 747C (ODP Leg 120) and Holes 1136A, 1137A, 1138A, and 1140A (ODP Leg 183) of the Kerguelen Plateau are altered to various degree in low-temperature hydrothermal environment. Temperature of alteration reached 150 degreesC and probably higher at alteration of basalts from Hole 1138A. Obtained results on the mobility of chemical elements due to alteration of basalts from the Kerguelen Plateau at sea water-rock interaction revealed that in << non-oxidative >> environment of alteration loss of most elements (Si, Fe, Mn, Ca, K, Cu, Zr, Y, So, Nb, Rb, Ba, Th, Sr, and REE) prevails. On the contrary, in the oxidative environment basalts accumulate K, Fe, P, Sr, Ba, and REE. Alteration of effusive basalts is related mainly to horizontal fluid flows within highly permeable contact zones between lava flows.