Early Holocene planktic foraminifers record species-specific 14 C reservoir ages in Arctic Gateway

• Published in: Marine Micropaleontology
• Main Authors: Sarnthein, Michael, Werner, Kirstin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2017
• Subjects: Arctic; Barents Sea; Norwegian Sea; Foraminifera*; Fram Strait; Neogloboquadrina pachyderma; Nordic Seas; Spitsbergen
• Online Access: https://oceanrep.geomar.de/id/eprint/39232/; https://oceanrep.geomar.de/id/eprint/39232/1/Sarnthein.pdf; https://oceanrep.geomar.de/id/eprint/39232/2/Sarnthein_Suppl.docx; https://doi.org/10.1016/j.marmicro.2017.07.002

Highlights • Planktic foraminifera species show an Early Holocene 14C plateau analogous to the atmospheric 14C plateau at 10.2–9.6 cal ka. • Age-calibrated Early Holocene 14C plateau boundaries provide precise age control in 3 sediment cores on a 900 km long transect. • Differences between planktic foraminiferal and atmospheric 14C ages reveal the 14C reservoir age of local surface waters. • Different planktic species document different 14C reservoir ages characteristic of different surface and subsurface waters. To trace spatial variations in Holocene reservoir ages of surface and subsurface waters we studied narrowly spaced 14C records of planktic foraminifera in three high-sedimentation rate cores from the Nordic Seas, the Barents Sea continental margin and eastern Fram Strait. The two northern cores reveal a distinct Early Holocene 14C plateau in dates on the subsurface dweller Neogloboquadrina pachyderma at 9.3–9.1 14C ka. The plateau was tuned to an atmospheric 14C plateau at 9.0–8.7 14C ka that spans 10.2–9.6 calendar ka. These two plateau boundaries provide robust age control points to estimate short-term changes in sedimentation rate and to correlate paleoceanographic signals over 900 km along the West Spitsbergen Current. The difference between planktic and atmospheric 14C plateau ages suggests local 14C reservoir ages of 370–400 yr. Planktic foraminifera species that inhabit different water masses document different reservoir ages. By comparison, the subpolar N. incompta reveals a reservoir age of 150 yr, probably formed in well-mixed Atlantic-sourced waters during winter. The near-surface dweller Turborotalita quinqueloba shows an age of 290 yr in the Fram Strait, but one of 720 yr at the Barents Sea continental margin. The latter age suggests a calcification within old, meltwater-enriched Arctic surface waters admixed by the East Spitsbergen Current. Likewise, we assign an elevated reservoir age of 760 yr on mixed species at a Norwegian Sea site near 71°N to Preboreal meltwaters that spread from ...