Identification

Title

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

Abstract

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.

Resource type

dataset

Resource locator

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

function: download

Unique resource identifier

code

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

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Additional information source

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.

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

originating controlled vocabulary

title

GEMET - INSPIRE themes

reference date

date type

publication

effective date

2008-06-01

Keyword set

keyword value

Climate change

Carbonates

Calcium

Palaeoceanography

Chemical analysis

Magnesium

Isotopes

Climatology

Planktonic foraminifera

originating controlled vocabulary

title

BGS Thesaurus of Geosciences

reference date

date type

revision

effective date

2011

Keyword set

keyword value

NERC_DDC

Geographic location

West bounding longitude

-90.0000

East bounding longitude

150.0000

North bounding latitude

90.0000

South bounding latitude

-30.0000

Temporal reference

Temporal extent

Begin position

2015-08-17

End position

2016-07-10

Dataset reference date

date type

creation

effective date

2018-04-16

Frequency of update

notApplicable

Quality and validity

Lineage

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

Conformity

Conformity report

specification

title

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

reference date

date type

publication

effective date

2011

degree

false

explanation

See the referenced specification

Conformity report

specification

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

reference date

date type

publication

effective date

2010-12-08

degree

false

explanation

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

Data format

name of format

MS Excel

version of format

Constraints related to access and use

Constraint set

Limitations on public access

Constraint set

Limitations on public access

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.

Responsible organisations

Responsible party

contact position

Department of Earth Sciences

organisation name

University of Cambridge

full postal address

Downing Street

Cambridge

CB2 3EQ

United Kingdom

email address

not available

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact

organisation name

British Geological Survey

full postal address

Environmental Science Centre,Keyworth

NOTTINGHAM

NG12 5GG

United Kingdom

telephone number

+44 115 936 3100

email address

enquiries@bgs.ac.uk

responsible party role

pointOfContact

Metadata date

2021-07-20

Metadata language

eng