Low‐frequency Pliocene climate variability in the eastern Nordic Seas

Abstract

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Mid‐Piacenzian Variability of Nordic Seas Surface Circulation Linked to Terrestrial Climatic Change in Norway

“…Black line is the 5‐point running average; (h) relative abundance of cysts of P. reticulatum (yellow line), cysts of P. reticulatum with short processes (filled yellow area), F. filifera (light blue) and H. tectata (dark blue). Dark gray vertical bar indicates the possible presence of an hiatus over the most extreme part of marine isotope stage M2 (Risebrobakken et al, ). Light red bar marks the KM5c time slice chosen for data‐model comparison (Haywood, Dolan, et al, ).…”

“…A hiatus is present in the younger part (<3.14 Ma) of the Pliocene section (Jansen & Sjøholm, ). All records presented from Hole 642B follow the same age model (Risebrobakken et al, ).…”

“…(a) Global benthic oxygen isotope stack from Lisiecki and Raymo () and the 5‐point smoothed benthic oxygen isotope curve for Hole 642B from Risebrobakken et al (); (b, c) orbital solutions for mean daily insolation and obliquity from Laskar et al (); (d, f) relative abundance (colored lines) and concentration (black lines) of the dinocyst species H. tectata , F. filifera , and cysts of P. reticulatum ; (g) dinocyst burial flux (DBF, line with gray dots) and total dinocyst concentration (line with vertical bars); and (h) Dinocyst assemblage composition in Hole 642B. Dark gray vertical bar indicates the possible presence of an hiatus over the most extreme part of marine isotope stage M2 (Risebrobakken et al, ). Light red bar marks KM5c the time slice chosen for data‐model comparison (Haywood, Dolan, et al, ).…”

“…Marine palynomorphs (dinocysts and acritarchs) were analyzed in 44 samples from ODP Hole 642B between 68.45 and 66.95 m below seafloor, or 3.32 and 3.14 Ma (Risebrobakken et al, ; Shipboard Scientific Party, ), with three samples taken from De Schepper et al (). The <63 μm sediment fraction was used for palynomorph analysis as the samples were presieved in Bergen, Norway, to retain foraminifera for oxygen isotope analysis (Risebrobakken et al, ). The samples were prepared at the Palynological Laboratory Services Ltd, North Wales, and Northumbria University, Newcastle, using standard palynological techniques (details in De Schepper et al, ).…”

“…The dinocyst burial flux (DBF) was calculated based on the dinocyst concentrations using the following formula: with DBF in cysts/(cm 2 ka). C D is the dinocyst concentration (cysts/g), ρ the dry bulk density (g/cm 3 ) (Shipboard Scientific Party, ), and S the sedimentation rate (cm/ka) (Risebrobakken et al, ). The comparison of DBF with dinocyst concentrations gives an indication of the influence of productivity and/or sedimentation rate on the observed fluctuations.…”