Calcareous nannofossils anchor chronologies for Arctic Ocean sediments back to 500 ka

• Published in: Geology (Boulder) 2020-11, Vol.48 (11), p.1115-1119
• Main Authors: O'Regan, Matt, Backman, Jan, Fornaciari, Eliana, Jakobsson, Martin, West, Gabriel
• Format: Article
• Language: English
• Subjects: Age; algae; Arctic Coring EXpedition; Arctic Ocean; biozones; bulk density; calcareous composition; calibration; Cenozoic; chronology; chronostratigraphy; Coccolithophoraceae; cores; correlation; Diagnostic systems; Dominant species; Emiliania; Emiliania huxleyi; Fossils; Geochronology; Geology; Integrated Ocean Drilling Program; Leg 151; lithostratigraphy; Lomonosov Ridge; Marine sediments; microfossils; Microorganisms; nannofossils; Ocean Drilling Program; Oceans; ODP Site 910; ODP Site 911; Oxygen; Oxygen isotopes; paleo-oceanography; Pleistocene; Polarity; Pseudoemiliania; Pseudoemiliania lacunosa; Quaternary; Quaternary geology; reconstruction; Sediment; Sediments; Species; Temperature; uncertainty; Yermak Plateau
• ISSN: 0091-7613; 1943-2682; 1943-2682
• DOI: 10.1130/G47479.1

Poor age control in Pleistocene sediments of the central Arctic Ocean generates considerable uncertainty in paleoceanographic reconstructions. This problem is rooted in the perplexing magnetic polarity patterns recorded in Arctic marine sediments and the paucity of microfossils capable of providing calibrated biostratigraphic biohorizons or continuous oxygen isotope stratigraphies. Here, we document the occurrence of two key species of calcareous nannofossils in a single marine sediment core from the central Arctic Ocean that provide robust, globally calibrated age constraints for sediments younger than 500 ka. The key species are the coccolithophores Pseudoemiliania lacunosa, which went extinct during marine isotope stage (MIS) 12 (478-424 ka), and Emiliania huxleyi, which evolved during MIS 8 (300-243 ka). This is the first time that P. lacunosa has been described in sediments of the central Arctic Ocean. The sedimentary horizons containing these age-diagnostic species can be traced, through lithostratigraphic correlation, across more than 450 km of the inner Arctic Ocean. They provide the first unequivocal support for proposed Pleistocene chronologies of sediment from this sector of the Arctic, and they constitute a foundation for developing and testing other geochronological tools for dating Arctic marine sediments.