11:00 AM - 11:15 AM
[BPT06-08] Late Eocene–early Oligocene deep-sea ostracode faunas at Integrated Ocean Drilling Program Site U1411, off Newfoundland, northwestern Atlantic
Keywords:Eocene, Expedition 342, Integrated Ocean Drilling Program, North Atlantic, Oligocene, Ostracoda
At Site U1411 (41°37’5.94”N, 48°59’59.94”W), three holes were drilled on the seafloor of the Southeast Newfoundland Ridge at 3299 m depth (Norris et al., 2014, Proc. IODP, 342). I took 132 sediment samples of ~20 cm3 volume from silty clay with nannofossils (140 to 235 m CCSF) and nannofossil chalks with foraminifers (235 to 266 m CCSF). Using the planktic foraminferal and calcareous nannofossil biostratigraphy, the core sediments are dated to be ~37.9–33.4 Ma, the late Eocene to early Oligocene (Norris et al., 2014).
Entirely 332 specimens were obtained from 67 of 132 sediment samples. 23 taxa were identified. Through the late Eocene to the early Oligocene, Krithe crassicaudata occurs most frequently. Henryhowella asperrima and Platyleberis sp. are often found. The samples contain Poseidonamicus pseudorobustus. The faunas contain the genera diagnostic for the NADW. At ~36.4 Ma, the ostracode abundance dropped off from 1–27 to 1–9 specimens, indicating changes in export productivity. The decrease in the abundance fell in the Late Eocene warming event of Bohaty and Zachos (2003, Geology, 31, 1017–1020). The faunas show no clear changes in taxonomic composition at and above the E/O boundary (33.7 Ma). At ~33.7 Ma, an increase in abundance of Krithe is observed and is coincidently with “Krithe pulse” in the Massignano Global Stratotype Section and Point in the Tethys Ocean (Slotnick and Schellenberg, 2013, Mar. Micropal., 103, 68–84).