Coupled Mg/Ca - D47 isotope data on foraminifera and calibration samples (NERC grant NE/M003752/1)

The modified cleaning procedure includes the following steps: (i) crushing of the shells; (ii) clay removal using deionized water and methanol in an ultrasonic bath; (iii) removal of organics using 5% H2O2 at room temperature, buffered with 0.1 M NaOH; (iv) check for potential contamination (e.g. silica grains) under the microscope and removal of contaminants if necessary. After drying at room temperature under vacuum, the samples were powdered between glass plates and split into 7 or more aliquots (120–140 lg each) for clumped isotope analyses, plus one aliquot (_250 lg) for Mg/Ca ratio analysis using the method of de Villiers et al. (2002). To the greatest extent possible, the method ensures that the Mg/Ca ratios and D47 values were measured on the same specimens of foraminifera. Clumped isotope measurements were performed at the Godwin Laboratory for Palaeoclimate Research, University of Cambridge, United Kingdom. The Thermo Scientific MAT253 mass spectrometer is equipped with 7 collectors to simultaneously measure masses 44 through 49. To monitor instrumental background during analysis, we use a cup located in a position corresponding to m/z 46.5 with a 1012 X resistor. This setup allows online monitoring of the impact of secondary electrons generated by the large m/z 44 beam on the smaller m/z beam of interest. Between 6 and 15 aliquots of calcium carbonate were reacted with orthophosphoric acid at 70°C using a Thermo Scientific Kiel IV carbonate device. The cryogenic trapping system of the Kiel device was modified by adding a Porapak trap that is cooled with two Peltier elements to remove organic compounds and isobaric contaminants prior to isotopic measurements (Schmid and Bernasconi, 2010; Schmid et al., 2012; Petersen and Winkelstern, 2016). This trap is cooled to ca. -12°C during each run and baked out for at least 1 h before the next run. For each replicate, the initial beam intensity of m/z 44 was around 20 V and decreased to ca. 12 V over the course of 8 cycles. The mass spectrometer uses standard stainless steel capillaries supplied by Thermo Scientific. Data were reduced using the evaluation scheme developed by Meckler et al. (2014). Pressure sensitive negative backgrounds on the rare isotopologue masses were determined before each run by performing peak shape scans on all masses at different intensities on m/z 44 (25 V, 20 V, 15 V and 10 V). These negative backgrounds originate from secondary electrons of the m/z 44 beam and by determining the m/z 44 pressure dependence with the background scans we can eliminate the mass spectrometer specific non-linearities observed in D47 versus d47 plots (Bernasconi et al., 2013; Meckler et al., 2014; Müller et al., 2017a) (Fig. S1). In addition, the m/z 46.5 intensity monitors the negative background signal originating from the m/z 44 beam online during acquisition. The m/z 44 pressure dependent behavior of the m/z 46.5 signal should correlate with the pressure dependent backgrounds of m/z 47 and in case of distinct behavior can be used to track measurements with contamination. The background is tracked using both the slope and intercept of m/z 46.5 and m/z 47, whereby an increase in the slope indicates contaminants in the instrument. More details can be found in Breitenbach et al. (2018) in GCA, doi: https://doi.org/10.1016/j.gca.2018.03.010

INSPIRE Implementing rules laying down technical arrangements for the interoperability and harmonisation of Geology

Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services