Formation of clay minerals during early diagenesis of a calcareous ooze

Deep-sea sediments from a basin in the Southeast Pacific are described, in which strong carbonate dissolution and strong diagenetic migration of metals can be observed. Clay minerals of smectite type are formed in large quantities during the early diagenesis of this sediment, in a first stage as an X-ray amorphous phase, which later crystallizes to smectite. Rb, Sc, Na and K become enriched during the process of clay-mineral formation, probably due to uptake of these elements from sea-water to interlayer positions of smectite. The unsolved question is what sort of mechanism connects the calcite dissolution with the formation of smectite? The source of the Al, necessary for the formation of smectite is also unknown.