Testing the stratigraphic consistency of Pleistocene microfossil bioevents identified on the Alpha and Lomonosov Ridges, Arctic Ocean

ABSTRACT

Two different biostratigraphic approaches are used to identify Marine Isotope Stage 11 (MIS 11) in Arctic Ocean sediments. On the Lomonosov Ridge, globally calibrated nannofossil bioevents constrain the age of sediments back to MIS 13 (Core LOMROG12-3PC). In the Amerasian Basin the unique occurrence of the planktonic foraminifer Turborotalita egelida is increasingly used as a marker for MIS 11. However, the T. egelida horizon has only been dated using cyclostratigraphy. Here we bridge these approaches through investigation of a new core (AO16-8GC) from the Alpha Ridge, Amerasian Basin. AO16-8GC is easily correlated to LOMROG12-3PC and contains the T. egelida horizon, allowing the first comparison between the biostratigraphy of both regions. Based on the nannofossil biochronology of LOMROG12-3PC, the most convincing lithologic correlation between the Alpha and Lomonosov Ridge cores places the T. egelida horizon between MIS 15 and MIS 17. This potentially older age for the T. egelida biohorizon emphasizes the need for continued caution in interpreting paleoceanographic records predating MIS 6, until further work can reconcile the nanno- and microfossil biostratigraphies that are emerging for middle Pleistocene sediments of the central Arctic Ocean.

KEYWORDS:

• Arctic
• biostratigraphy
• foraminifera
• geochronology
• paleoceanography

Acknowledgments

The captain and crew of I/B Oden are thanked for core collection. Kjell Jansson is thanked for help with SEM images and Carina Johansson for producing XRF data.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data

The data related to this article can be accessed at the Bolin Centre database. https://doi.org/10.17043/oden-ao-2016-sediment-ao16-8gc-forams-xrf-1.

List of foraminifer species

Planktonic

Neogloboquadrina pachyderma (Ehrenberg, 1861)

Turborotalita egelida (Cifelli and Smith, 1970)

Turborotalita quinqueloba (Natland, 1938)

Benthic

Bolivina arctica (Herman, 1973)

Oridorsalis tener (Brady, 1884)

Cibicidoides wuellerstorfi (Schwager, 1866)

Stetsonia horvathi (Green, 1960)

Additional information

Funding

FV was supported by the Swedish Research Council under Grant DNR 2019-03757, MO was supported by the Swedish Research Council under Grant DNR-2020-04379. TMC was funded by the U.S. Geological Survey Climate Research and 700 Development Program. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.