Alkenone sea surface temperatures Uk'37-SST from sediment core MD01-2444 on the Portuguese Margin, Marine Isotope Stage 3

• Main Authors: Tzedakis, Polychronis C, Margari, Vasiliki, Skinner, Luke C, Menviel, Laurie, Capron, Emilie, Rhodes, Rachael H, Mleneck-Vautravers, Maryline J, Ezat, Mohamed M, Martrat, Belén, Grimalt, Joan O, Hodell, David A
• Format: Dataset
• Language: English
• Published: PANGAEA 2020
• Subjects: Age model; GICC05; WD2014; Calculated from UK'37; CALYPSO; Calypso Corer; DEPTH; sediment/rock; GEOSCIENCES; MARMARCORE; Heinrich Stadials; Interstadials; Marion Dufresne (1995); MD01-2444; MD123; MIS 3; Portuguese Margin; Sea surface temperature; Greenland; ice core; NGRIP
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.919841; https://doi.org/10.1594/PANGAEA.919841

Alkenone SST: Sediment samples (2.5 to 2.57 g) were freeze-dried and extracted by sonication using dichloromethane. The extracts were dried under nitrogen and hydrolysed with 7% potassium hydroxide in methanol. Extraction with hexane yielded a fraction enriched in neutral compounds, which was cleaned with ultra-pure water. The purified extracts were derivatised with BSTFA. Samples were injected diluted in toluene. They were then analysed with a Varian gas chromatograph Model 3400 equipped with a septum programmable injector and a flame ionisation detector. Absolute concentration errors were below 10%. Reproducibility tests showed that the uncertainty in the Uk'37 determinations was lower than 0.015 (ca. ±0.5ºC). The SST reconstruction (Uk'37-SST) was obtained from the relative composition of C37 unsaturated alkenones [Uk'37 = C37:2/(C37:2+C37:3)], using the calibration equation Uk'37 = 0.033*SST+0.044. The record was generated by B. Martart and J.O. Grimalt. Age model: The age model was developed by aligning the abrupt transitions of d18O record of G. bulloides in core MD01-2444 to warming and cooling events in the NGRIP d18Oice record, presented on: (i) the GICC05 timescale [Svensson, A. et al. A 60,000 year Greenland stratigraphic ice core chronology. Clim. Past 4, 47–57 (2008)]; and (ii) the WD2014: modified timescale, whereby NGRIP GICC05 ice ages 31.2–67.2 ka are multiplied by 1.0063. [Buizert, C. et al. The WAIS Divide deep ice core WD2014 chronology – Part 1: Methane synchronization (68–31 ka BP) and the gas age–ice age difference. Clim. Past 11, 153-173 (2015)].