Reticulofenestra daviesii; biostratigraphy and paleogeographic distribution across the Eocene-Oligocene boundary

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doi: 10.1016/j.geobios.2017.07.002
Author(s): Bordiga, Manuela; Sulas, Camilla; Henderiks, Jorijntje
Author Affiliation(s): Primary:
Uppsala University, Department of Earth Sciences, Uppsala, Sweden
Other:
Florence University, Italy
Volume Title: Geobios
Source: Geobios, 50(5-6), p.349-358. Publisher: Elsevier on behalf of Université Claude Bernard, Département des Sciences de la Terre, Lyon, France. ISSN: 0016-6995 CODEN: GEBSAJ
Note: In English. Includes appendix. 72 refs.; illus., incl. 1 plate, 1 table, sketch map
Summary: Improving the biostratigraphy across the Eocene-Oligocene is fundamental to better constrain the timing and causes of an important global climate change of the Cenozoic, the Eocene-Oligocene Transition (EOT; 34-33.5 Ma). Across the EOT, only few nannofossil bioevents are considered globally synchronous and reliable. One of these is the first common occurrence (Bc) of the species Reticulofenestra daviesii that has been proven to be useful for biostratigraphical correlations in the Southern Ocean, but the potential of R. daviesii as a biostratigraphical marker at mid- and low latitudes has not been explored yet in detail. We investigate three deep-sea drill sites located across a N-S transect at mid-low latitudes of the Atlantic Ocean spanning from 34.4 to 33 Ma, reviewing the temporal and geographical distribution together with the intraspecific variability of R. daviesii. Our data quantify the occurrence of R. daviesii in (sub)tropical regions of the Atlantic Ocean, although with lower abundances (∼ 4-12%) compared to Southern Ocean assemblages (40-95%). This suggests that R. daviesii was a cosmopolitan species capable to adapt to a wider range of sea surface temperatures and environmental conditions than previously thought. However, the temporal distributions of R. daviesii at the three studied sites are not comparable to the trends recorded in the Southern Ocean. Its Bc is clearly identifiable only at the equatorial site, occurring ∼ 500,000 years before the age estimated in the Southern Ocean (33.705 Ma). Thus, we suggest caution when using the Bc of R. daviesii as a reliable biostratigraphical event at mid- and low latitudes. In addition, our biometrical data reveal that up to 38% of R. daviesii coccoliths is > 8-10 µm in major axis size, thus bigger than the medium size range (5-8 µm) originally described. Refining the size range of R. daviesii is important for estimating its cell volume versus surface area and coccolith carbonate mass.
Year of Publication: 2017
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Atlantic Ocean; Biogeography; Biometry; Biostratigraphy; Ceara Rise; Cenozoic; DSDP Site 612; Deep Sea Drilling Project; Eocene; Equatorial Atlantic; IPOD; Leg 154; Leg 208; Leg 95; Lower Oligocene; Microfossils; Morphology; Nannofossils; North Atlantic; ODP Site 1263; ODP Site 929; Ocean Drilling Program; Oligocene; Paleogene; Plantae; Reticulofenestra daviesii; Size; South Atlantic; Stratigraphic boundary; Tertiary; Upper Eocene; Walvis Ridge
Coordinates: N384912 N384913 W0724625 W0724626
N055834 N055834 W0434423 W0434423
S283200 S283200 E0024700 E0024700
Record ID: 2018031798
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands