Distribution and origin of authigenic smectite clays in Cape Roberts Project Core 3, Victoria Land Basin, Antarctica

Of some 800 m of lower Oligocene marine sediments cored continuously from the seafloor in the Victoria
Land Basin of Antarctica at Cape Roberts Site CRP-3, the lower 500 m exhibit authigenic smectite clay coats on
shallow-water sandstone grains. A scanning electron microscope/EDS study of 46 fracture sections confirms that the
distribution of the clay coats through the unit is not uniform or evenly distributed, but rather varies with depth, original
porosity, and the kinds and abundance of source materials. Our results suggest that smectite emplacement resulted from
in-situ, low-temperature burial diagenesis rather than hydrothermal or fault-focused thermobaric fluids.