Date (Creation)

2025-09-15

Citation identifier

http://data.bgs.ac.uk/id/dataHolding/13608533

Point of contact

Organisation name	Individual name	Electronic mail address	Role
University of Southampton	Professor Stephen Roberts	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

• Geochronology

• Lead

• NGDC Deposited Data

• Uranium

• Calcite

dataCentre

• NGDC Deposited Data

Keywords

• NERC_DDC

Access constraints

Other restrictions

Other constraints

licenceOGL

Other constraints

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

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

2020-09-01 Before

End date

2023-09-01 Before

Distribution format

Name	Version
Microsoft Excel (XLSX)

Distributor contact

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

OnLine resource

Protocol	Linkage	Name
WWW:DOWNLOAD-1.0-http--download	https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#item189927	Data

Hierarchy level

Non geographic dataset

Other

non geographic dataset

Statement

Laser Ablation U-Pb analyses at the NERC Laboratories Keyworth. Polished blocks measuring 25 mm in diameter were made from a total of 6 samples covering the Los Chihuidos, Barda González, La Cuprosa, El Porvenir and Tordillos Cu deposits. These included a grain mount of calcite 3 from Los Chihuidos and 5 sediment blocks. These blocks were selected to cover all the localities and calcite generations available in the sample suite, The polished blocks were carbon coated and analysed using a Zeiss EVO SEM at the NHM, London. Each block was BSE montaged and sites of interest selected before SEM-CL imaging was conducted. The BSE analytical conditions were 20Kv acceleration voltage, 10 mm working distance and 1.5 nA probe current. For SEM-Cl imaging, the conditions were 20 kv acceleration voltage, 1 mm working distance from the CL detector and the probe current increased to 3 nA. Images were processed using Zeiss Digiscan II software. Following BSE and SEM-Cl imaging, each block was sliced to create a polished thick section and thin section. The thin sections were analysed using standard polarising microscope techniques to establish mineralogy and cement textures. Each thick section was BSE scanned using a Leo 1450VP SEM equipped with an Oxford Instruments X-Act 10mm2 detector at the National Oceanography Centre, Southampton prior to CL imaging. Analytical conditions were 20 kv acceleration voltage, 2 nA probe current and 19 mm working distance. Cl Imaging was conducted on a Lumin hot-stage Cl microscope at the NHM, London. The acceleration voltage used was 10 kv with a beam current kept at ~0.2 nA. Sites identified on the CL microscope were subsequently overlain onto the BSE scan for sample navigation. After fully imaging and characterising each thick section, the samples were sent to the BGS, Nottingham for in-situ U-Pb calcite geochronology. Laser ablation was performed using a New Wave Research 193UC excimer laser coupled to a Nu Instruments Attom single collector sector field mass spectrometer. A spot size of 50 µm was used. The full analytical setup for the laser and mass spectrometer are provided in Roberts and Walker (2016). Standard sample bracketing utilised the NIST614 glass standard (Jochum et al., 2011) to normalise the 207Pb/206Pb ratio (Pbc) whilst the calcite standard WC-1 (Roberts et al., 2017) was used to correct the 206Pb/238U ratio. Data uncertainty and propagation protocols follow Horstwood et al., (2016). The U-Pb heterogeneity of current carbonate mineral standards are often equal to or larger than the analytical uncertainties, meaning that significant excess variance will be present in the reference material U-Pb measurements (Roberts et al., 2017). If propagated into the sample point uncertainties as a within-session excess variance, as recommended for zircon in Horstwood et al., (2016), the data point uncertainties will be overestimated and will mask any small-scale real geological scatter in the sample and lead to ages with erroneously high precision. As per the recommendations of (Roberts et al., 2020), session-based reproducibility, accuracy and precision was performed on more homogeneous standards such as zircon or NIST glass standard. Accuracy of the method and secondary reference material is provided in thesis, doi:10.5258/SOTON/D3219, section 3.5.2. All results are plotted using a Tera-Wasserburg concordia diagram, taking the lower intercept as the age of the analysis. No common Pb correction was applied to the data.

Metadata

File identifier

3f290c61-74a9-421a-e063-3050940ab292 XML

Metadata language

English

Hierarchy level

Non geographic dataset

Hierarchy level name

non geographic dataset

Date stamp

2025-12-06

Metadata standard name

UK GEMINI

Metadata standard version

2.3

Metadata author

Organisation name	Individual name	Electronic mail address	Role
British Geological Survey		enquiries@bgs.ac.uk	Point of contact

Dataset URI

http://data.bgs.ac.uk/id/dataHolding/13608533