Northern source for Deglacial and Holocene deepwater composition changes in the Eastern North Atlantic Basin

Moving beyond the age-depth model paradigm in deep sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera

“…Specifically, we find good temporal agreement with the absolute values for δ 18 O, indicating a valid benthic deglaciation signal. We also find good temporal agreement with a sharp peak in δ 13 C values that has previously been interpreted as a local increase in Eastern North Atlantic Deep Water (ENADW) linked to the onset of the Holocene (Repschläger et al, 2015). These results demonstrate that it is possible to use our dual 14 C and stable isotope method on single foraminifera to extract temporally accurate late-glacial benthic palaeoceanographic data from a low SAR site, with 225 comparable success when compared to data extracted from a high SAR site using the existing state-of-the-art.…”

“…Horizontal error bars denote the 68.27% highest posterior density interval of the calibrated 14 C age (see method for 14 C calibration process). Also shown are previously published multi-specimen δ 18 O data from a nearby high SAR (20 cm/ka) record (Repschläger et al, 2015). Vertical error bars represent 1σ measurement error.…”

Moving beyond the age–depth model paradigm in deep-sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera

“…We chose core T86-10P for this study because preliminary oxygen isotope measurements on planktonic foraminifera indicated a poor multi-specimen glacial-interglacial δ 18 O stratigraphy, typical of a low-SAR sediment core (Metcalfe, 2013). Also, the nearby presence of a very high SAR record at a similar water depth (Repschläger et al, 2015) provides an ideal local "reference" stratigraphy for direct comparison. In other words, core T86-10P is an ideal sediment core with which to test the ability of dual 14 C and stable isotope analysis on single foraminifera to successfully extract temporally accurate palaeoclimate data from a very low-SAR archive.…”

“…Considering the aforementioned complications associated with the age-depth model method, high-resolution sampling of core depth does not necessarily translate into highresolution sampling of time. Researchers are aware that the concealment of intra-sample age heterogeneity can pose problems for the age-depth model method (Bard, 2001; Keigwin and Gagnon, 2015;Löwemark and Grootes, 2004;Löwemark and Werner, 2001;Pisias, 1983;Ruddiman and Glover, 1972), which can potentially lead to incorrect interpretations of temporal climate offsets as well as apparent 14 C age offsets between different species and/or sizes of foraminifera that are, in fact, an artefact of PDSM (Berger, 1977;Löwemark et al, 2008;Löwemark and Grootes, 2004;Peng and Broecker, 1984). With these problems in mind, researchers seeking to reconstruct rapid (i.e.…”

Reply to Reviewer #1 (P. Ascough)

“…Considering the aforementioned complications associated with the age-depth model method, high-resolution sampling of core depth does not necessarily translate into highresolution sampling of time. Researchers are aware that the concealment of intra-sample age heterogeneity can pose problems for the age-depth model method (Bard, 2001;Keigwin and Gagnon, 2015;Löwemark and Grootes, 2004;Löwemark and Werner, 2001;Pisias, 1983;Ruddiman and Glover, 1972), which can potentially lead to incorrect interpretations of temporal climate offsets as well as apparent 14 C age offsets between different species and/or sizes of foraminifera that are, in fact, an artefact of PDSM (Berger, 1977;Löwemark et al, 2008;Löwemark and Grootes, 2004;Peng and Broecker, 1984). With these problems in mind, researchers seeking to reconstruct rapid (i.e.…”