Biostratigraphic analyses might have provided a maximum age estimate for the Nuulau landslide had we found adequately preserved fossils in the sedimentary section below the landslide section. However, Hole 1223A may not have penetrated subslide sediments, and the Eocene Radiolaria assemblage observed in Intervals B and D indicate only a maximum age for timing of the turbidite events recovered in the sediment column above 41 mbsf. In this case, the maximum age has little value, but the Neogene Radiolaria fauna in Subintervals B1–B2 provide a minimum age of 1.8 Ma for the turbidites below 3 mbsf and a maximum age of 2.0 Ma for the turbidites of Interval A. We have made extensive examinations of our prepared samples from Interval A in order to obtain biostratigraphic age control, but the paucity of microfossils, including Radiolaria, precludes this objective.
We speculate on the basis of inconclusive evidence that the heat source responsible for induration of the section below Core 200-1223A-2H and opal-CT recrystallization in Interval D may be located in the section below 41 mbsf at Site 1223. Furthermore, we suggest that volcaniclastic-rich sediments of lithologic Unit 2 may represent a local cohesive slump rather than stacked distal turbidites.