抄録
ransmission electron microscopy of clay minerals in North Pacific deep-sea sediments has revealed the existence of intermediate states between montmorillonite, talc and palygorskite. During the earliest diagenetic stages of montmorillonite, short needles grow from the rim of montmorillonite films, and sometimes from rims of talc. The short needles, 0.1μE in length, are incorporated into the palygorskite. The electron diffraction patterns of the primitive palygorskite show well defined spots at 4.49, 2.61, 2.26 and 1.70Åsuggesting high crystallinity. The short needles precede formation of elongated fibres with sharp edges which eventually form lamellae aggregates and fibre bundles. EDX analysis shows that the major element concentrations of bundled palygorskite are Mg, Al, Fe and Si (1:1.2:1:5.1). XRD, DTA and SIMS data support these TEM results. The formation of magnesium-rich clay minerals during diagenetic processes in deep-sea sediments could be a significant sink in the marine magnesium cycle.
