Stable isotopes and Mg/Ca of sediment core MSM45/19-2

• Main Authors: Lochte, Annalena Antonia, Schneider, Ralph R
• Format: Dataset
• Language: English
• Published: PANGAEA 2022
• Subjects: 8.2 ka event; AGE; Bottom water temperature; standard deviation; Calculated from Mg/Ca ratios and d18O and corrected for ice volume; Calculated from Mg/Ca ratios and d18O corrected; DEPTH; sediment/rock; GC; Gravity corer; Inductively coupled plasma-optical emission spectrometry (Iris Intrepid II ICP-OES); Islandiella helenae; Magnesium/Calcium ratio; δ18O; Labrador Sea; Maria S. Merian; Mass spectrometer; Thermo Finnigan; MAT 253; Mg/Ca-based paleotemperatures; MSM45; MSM45_418-2; MSM45-19-2; stable oxygen isotopes; ice volume free; seawater; reconstructed; Hudson Bay; Canada; Hudson; Labrador Shelf; Arctic; Northwest Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.945715; https://doi.org/10.1594/PANGAEA.945715

The presented data originates from the 1306cm long gravity core MSM45-19-2 (58°45.68 N, 61°56.25 W, 202m water depth) taken during R/V Maria S. Merian cruise MSM45 in August 2015 at 202 m water depth on the northern Labrador Shelf, northeast Canada, northwest Atlantic. Here, we present a high-resolution and well-dated sediment record from the northern Labrador Shelf that provides new evidence of the freshwater signature and the mechanisms involved in the Hudson Bay Ice Saddle collapse. A combination of Mg/Ca ratios and stable oxygen isotopes of benthic foraminifera indicate temperature changes and freshening of Labrador Shelf bottom waters. About 60 specimens of I. helenae were handpicked from the 200–315 μm fraction in 5-cm intervals downcore, weighed, and crushed between two glass plates. The crushed samples were then split for Mg/Ca and stable isotope measurements (see below). About two thirds of each crushed sample was transferred into pre-leached Eppendorf vials and cleaned following the full protocol of Martin and Lea (2002), including a reductive and oxidative cleaning step and a final leaching step with 0.001 N HNO3. After dissolving and diluting the samples in 0.1 N HNO3, they were measured with an inductively coupled plasma-optical emission spectrometry (ICP-OES) instrument with radial plasma observation at the Institute of Geosciences, Kiel University. The analytical error of Mg/Ca analyses was 0.1% relative standard deviation and accuracy was monitored with reference material JCP-1. Additional trace elements (Fe, Al, and Mn) were monitored to exclude possible contaminated or coated samples from the dataset. Based on 15 duplicate down-core sample measurements, we obtained a standard deviation of 0.07 mmol/mol Mg/Ca, which translates into 0.9 °C with respect to temperature estimates. For bottom water temperature reconstructions, we applied the calibration of Skirbekk et al. (2016). As the calibration is based on a temperature range of 1–4 °C, it may become less accurate when temperatures exceed 4 °C, ...