Preboreal onset of cold-water coral growth beyond the Arctic Circle revealed by coupled radiocarbon and U-series dating and neodymium isotopes
Lopez Correa, M.; Montagna, P.; Joseph, N.; Rüggeberg, A.; Fietzke, J.; Flogel, S.; Dorschel, B.; Goldstein, S.L.; Wheeler, A.; Freiwald, A. (2012). Preboreal onset of cold-water coral growth beyond the Arctic Circle revealed by coupled radiocarbon and U-series dating and neodymium isotopes. Quat. Sci. Rev. 34: 24-43. dx.doi.org/10.1016/j.quascirev.2011.12.005 In: Quaternary Science Reviews. Pergamon Press: Oxford; New York. ISSN 0277-3791; e-ISSN 1873-457X, more |  |
| Keyword | | | Author keywords | Cold-water corals; Reservoir ages; Biogeography; Rapid climate change;Younger Dryas; Deglacial; Water mass mixing |
| Authors | | Top | - Lopez Correa, M.
- Montagna, P.
- Joseph, N.
- Rüggeberg, A., more
| - Fietzke, J.
- Flogel, S.
- Dorschel, B.
| - Goldstein, S.L.
- Wheeler, A.
- Freiwald, A.
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| Abstract | Cold-water coral mounds of Lophelia pertusa are widespread across the Scandinavian shelf, which was completely ice-covered during the Last Glacial Maximum between 22 to 18 ka BP. Rapid deglacial meltdown of the Fennoscandian inland ice and the retreat of its ice-streams freed most of the shelf of ice by ~15 ka BP. However, cold-water coral growth commenced only after the Pleistocene–Holocene transition at 11.65 ka BP, when modern-like climatic patterns and oceanographic conditions were established. A tight climatic coupling has been constrained with U-series ages. Coupled 14C ages provide local reservoir ages from various gravity cores in a fjord-setting in Stjernsund at 70°N and on the open shelf in Trænadjupet at 66°N. Reinvestigation of earlier 14C coral chronologies suggests that coral ecosystems widely established themselves across the entire 3000 km long Scandinavian shelf prior to ~10 ka BP. The earliest occurrence of Madrepora oculata at ~2.4 ka BP suggests a late Holocene colonization of the Norwegian shelf, which is linked to a prominent mound growth hiatus in Trænadjupet (64°N). Mound growth rates near the northern biogeographic boundary of L. pertusa with up to ~614 cm ka-1 during certain growth periods are much higher than the previously reported fastest rates of ~220 cm ka-1 from the Irish margin. Contemporaneous rapid fjordbasin sedimentation is slower with ~63 cm ka-1. Matrix 14C ages overlap with coral 14C ages from the same horizon. This indicates rapid framework construction and efficient trapping of background sediment. Hiatuses are frequent in on-mound sediments and only short periods of coral growth are recorded. Coupled ?14C and eNd values indicate a persistent Holocene inflow of the North Atlantic Current in Stjernsund, but also deglacial meltwater mixing during the early Holocene prior to ~9.5 ka BP. Reservoir ages are overall close to the surface marine reservoir age, but ?R is highly localized. |
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