Hydrothermal vents at MOR (smokers), I
At MOR, formation of new lithosphere fractures rock & brings magma to shallow depths
Sea water percolates into rock along fractures, heats up, & rises through the oceanic crust to escape into sea water at hydrothermal vents
Hot water is chemically active & metamorphoses basalt as it travels through crust
Process also alters the types & concentrations of dissolved solids