(Table 2) Stable isotopes in foraminifers at DSDP Leg 78, supplement to: Keigwin, Lloyd D (1982): Stable isotope stratigraphy and paleoceanography of Sites 502 and 503. In: Prell, WL; Gardner, JV; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 68, 445-453

• Main Author: Keigwin, Lloyd D
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 1982
• Subjects: Event label; Latitude of event; Longitude of event; Elevation of event; Sample code/label; DEPTH, sediment/rock; Cibicidoides wuellerstorfi, δ18O; Cibicidoides wuellerstorfi, δ13C; Cibicidoides kullenbergi, δ18O; Cibicidoides kullenbergi, δ13C; Globigerinoides quadrilobatus, δ18O; Globigerinoides quadrilobatus, δ13C; Oridorsalis tener, δ18O; Oridorsalis tener, δ13C; Drilling/drill rig; DSDP/ODP/IODP sample designation; see references; Leg68; Glomar Challenger; Deep Sea Drilling Project DSDP; Gardner; Pacific; North Atlantic Deep Water; North Atlantic
• Online Access: https://dx.doi.org/10.1594/pangaea.817079; https://doi.pangaea.de/10.1594/PANGAEA.817079

Analyses of stable isotopes of monospecific planktonic foraminifers (G. quadrilobatus group) and monogeneric benthic foraminifers (Cibicidoides spp.) from late Neogene Atlantic Site 502 and Pacific Site 503 were conducted in order to determine the paleoceanographic changes resulting from the late Neogene uplift of the Panama Isthmus and from climatic cooling. In general, results at each site are similar to those from previous studies for the late Miocene and late Pliocene time interval, documenting the late Miocene (6 Ma) shift in carbon isotopes and the inferred growth of permanent Northern Hemisphere continental ice sheets beginning about 3.2 Ma. Comparison of Atlantic-Pacific planktonic-benthic isotope data for four stratigraphic intervals (~6-8, ~5-6, ~3-5, and ~2-3 Ma) suggests that increasing isolation of Atlantic and Pacific low-latitude waters may be related to the emergence of the Panama Isthmus. The contrast between Atlantic and Pacific benthic foraminiferal d13C increased in two steps from 0.60 per mil to 1 per mil (the modern contrast) at about 6 Ma and 3 Ma. The first increase (0.15 per mil) may represent the end of previously limited deep-water communication between the Atlantic and Pacific at the present location of Panama. The second increase (0.25 per mil) may be due to increased production of North Atlantic Deep Water. This probably reflects the development of modern deep-sea circulation. The d18O of planktonic foraminifers begins to increase in Atlantic Site 502 at 4.2 Ma and may reflect the increasing salinity of the North Atlantic Ocean arising from diminishing surface-water exchange across Panama. This increase is clearly shown by contrasting the d18O of Atlantic and Pacific planktonic foraminifers, as well as the d18O of planktonic and benthic foraminifers at Site 502. This inferred increase in surface-water salinity begins at the time of increasing provinciality of Atlantic and Pacific planktonic foraminifers.