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doi:10.2204/iodp.proc.340.103.2013

Paleontology and biostratigraphy

Core catcher samples from Site U1393 are largely composed of sandy to coarse volcanic material (see “Lithostratigraphy”) and contain very few micro- and nannofossils. Retrieved microfossils are consistent with reworked material, showing the presence of shallow-water reef species and high test fragmentation.

Calcareous nannofossils

Because of the coarse nature of sediment retrieved at Site U1393, nannofossil analysis was only appropriate for two of the seven core catcher samples collected. No datum marker species were found in either core catcher sample; thus, age determination could not be made. The species Gephyrocapsa aperta (few) and Gephyrocapsa caribbeanica (common) were found in the uppermost core (Sample 340-U1393A-1H-CC). Ceratolithus spp. was found in low numbers (few), possibly because of the poor preservation of the sample. Nannofossil content in Sample 340-U1393A-7X-CC was extremely low. Specimens present were very small and could not be identified using optical light microscopy. Further postcruise analysis with the use of scanning electron microscopy is required for this sample.

Planktonic foraminifers

The low number of calcareous microfossil specimens collected at Site U1393 was insufficient to provide any chronostratigraphic information. Four of the seven core catcher samples retrieved were analyzed for microfossil content. Only two samples contain calcareous microfossils. One fragment of an unidentifiable planktonic foraminifer was found in Sample 340-U1393A-1H-CC. Three specimens of planktonic foraminifers commonly found in the modern-day Caribbean Sea (Bé, 1977) (one of each species: Globigerinoides ruber [pink], Globigerinoides sacculifer, and Neogloboquadrina dutertrei) and one unidentifiable fragment of a planktonic foraminifer were found in Sample 340-U1393A-2H-CC. In addition, one heteropod and one bivalve specimen were found and the presence of large shell fragments was noted. The condition of the foraminifers is generally poor, suggesting transportation consistent with reworked material.

Benthic foraminifers

Four benthic foraminifers were recorded from two samples at Site U1393. Three of the foraminifers are from shallow-water reef environments (Amphistegina lessonii, Cyclorbiculina compressa, and Asterigerina sp.). A fourth specimen is encrusted with limestone, making identification impossible. The very low diversity (1–3 specimens/sample) and poor preservation of benthic foraminifers does not allow for proper paleobathymetric approximation. However, the species found are common in environments of <30 m water depth, suggesting transported and reworked material.