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

We used existing coretop samples from several sites from the Atlantic, Arctic, Pacific, and Indian Oceans (Fig. 1 and Table S1) to test the relationship between Mg/Ca ratios and D47 values in modern foraminifera. In the North Atlantic the cores were the same as those used previously by Elderfield and Ganssen (2000) (Tables S1 and S2). Coretops with the potential to yield large (>5 mg) mono-specific samples of foraminifera were selected from the >300 lm size fraction of the sediment except for Neogloboquadrina pachyderma (sinistral) where the >150 lm size fraction was chosen to obtain sufficient material. After cleaning the samples consisted of _3 mg of foraminiferal calcite and included 8 different species of surface- and deepdwelling planktonic foraminifera: Globigerina bulloides, Globigerinoides sacculifer, Globorotalia hirsuta, Globorotalia inflata, Globorotalia menardii, Neogloboquadrina dutertrei, Neogloboquadrina pachyderma (s), and Orbulina universa. The Godwin Laboratory clumped isotope calibration (i.e., the regression between D47 and temperature) was established using natural cave carbonates that precipitated subaqueously at known temperatures, ranging from 3 to 47ºC (Table 1, Fig. 2). These carbonates grew under conditions that minimize CO2-degassing and evaporation and hence kinetic fractionation effects are negligible owing to an unlimited DIC pool in the water (Kele et al., 2015). All samples consist of calcite, except NAICA-1 which is aragonite.

Date (Creation): 2018-04-16

Citation identifier: http://data.bgs.ac.uk/id/dataHolding/13607302

Point of contact

Organisation name	Individual name	Electronic mail address	Role
University of Cambridge	Professor D A Hodell	not available	Originator
British Geological Survey	Enquiries	not available	Distributor
British Geological Survey	Enquiries	not available	Point of contact

Maintenance and update frequency: notApplicable

GEMET - INSPIRE themes, version 1.0

Geology

BGS Thesaurus of Geosciences

Calcium
Isotopes
Magnesium
Planktonic foraminifera
Carbonates
Climate change
NGDC Deposited Data
Climatology
Chemical analysis
Palaeoceanography

dataCentre

NGDC Deposited Data

Keywords

NERC_DDC

Access constraints: Other restrictions

Other constraints: no limitations

Other constraints: The dataset is made freely available for access, e.g. via the Internet. Either no third party data / information is contained in the dataset or BGS has secured written permission from the owner(s) of any third party data / information contained in the dataset to make the dataset freely accessible.

Use constraints: Other restrictions

Other constraints: The copyright of materials derived from the British Geological Survey's work is vested in the Natural Environment Research Council [NERC]. No part of this work may be reproduced or transmitted in any form or by any means, or stored in a retrieval system of any nature, without the prior permission of the copyright holder, via the BGS Intellectual Property Rights Manager. Use by customers of information provided by the BGS, is at the customer's own risk. In view of the disparate sources of information at BGS's disposal, including such material donated to BGS, that BGS accepts in good faith as being accurate, the Natural Environment Research Council (NERC) gives no warranty, expressed or implied, as to the quality or accuracy of the information supplied, or to the information's suitability for any use. NERC/BGS accepts no liability whatever in respect of loss, damage, injury or other occurence however caused.

Other constraints: Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]"

Language: English

Topic category

Geoscientific information

Begin date: 2015-08-17

End date: 2016-07-10

Supplemental Information: We thank Gerald Ganssen (Amsterdam Global Change Institute) for use of his sample collection. Ludvig Löwemark (National Taiwan University) and Richard Gyllenkreutz (Stockholm University) kindly provided some Arctic samples and the Taiwan Ocean Research Institute provided the sample from the Okhotsk Sea. Professors Paolo Forti and Jose Maria Calaforra provided the sample NAICA-01. Harry Elderfield contributed to this study with his deep insights into the (bio)geochemistry of foraminifera.

Reference System Information

No information provided.

Distribution format

Name	Version
MS Excel

Distributor contact

Organisation name	Individual name	Electronic mail address	Role
British Geological Survey	Enquiries	not available	Distributor

OnLine resource

Protocol	Linkage	Name
	http://www.bgs.ac.uk/services/ngdc/accessions/index.html#item109449

Hierarchy level: Dataset

Other: dataset

Conformance result

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

Date (Publication): 2011

Explanation: See the referenced specification

Pass: No

Conformance result

Title: 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

Date (Publication): 2010-12-08

Explanation: See http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:323:0011:0102:EN:PDF

Pass: No

Statement: 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