Five sites were drilled in the Caribbean region during Ocean Drilling Program (ODP) Leg 165, but only three (Fig. 1) were examined for radiolarians. The main objectives of the leg were to examine the nature of the Cretaceous/Tertiary (K/T) boundary and to study the influence of tropical seas on global climate and ocean history. The initial Deep Sea Drilling Project (DSDP) policy of discontinuous coring yielded good, but intermittent, sequences from the Caribbean (Legs 4, 10, and 15). Given the superior drilling and continuous recovery now possible, it was thought that a reasonably good Paleogene radiolarian-bearing sequence might be obtained in this region. Hence, radiolarian samples were taken from Holes 998A, 998B, 999B, 1001A, and 1001B with the expectation that they would provide a continuous record of radiolarian deposition in the region. It was hoped that we could examine the paleoenvironmental signals provided by radiolarians during the interval surrounding the late Paleocene thermal maximum (LPTM) and that we could construct an integrated chronostratigraphy, using datum levels from radiolarians, calcareous microfossils, paleomagnetism, and isotopes, in and around critical, datable ash layers.
Unfortunately, the results have been disappointing in that radiolarian preservation is uneven and not as good as that found in earlier legs. Sample preparation proved to be both extremely difficult and time consuming, and the resulting assemblages are so poor that we were unable to make detailed biostratigraphic and taxonomic determinations. However, some partial stratigraphies could be constructed, and we have found a recognizable change in radiolarian abundance and preservation associated with the LPTM interval.