568f784c-1756-e7a0-e063-3050940af7ef English nonGeographicDataset non geographic dataset British Geological Survey +44 115 936 3100 Environmental Science Centre,Keyworth NOTTINGHAM NOTTINGHAMSHIRE NG12 5GG United Kingdom enquiries@bgs.ac.uk pointOfContact 2026-08-25 UK GEMINI 2.3 http://data.bgs.ac.uk/id/dataHolding/13608743 Paleomagnetic and paleointensity data from two Cambrian igneous sequences: 505 Ma Bourinot volcanic rocks of Cape Breton Island, Nova Scotia, Canada, and 525 Ma Itabaiana mafic dyke swarm of northeastern Brazil 2026-07-10 creation http://data.bgs.ac.uk/id/dataHolding/13608743 The dataset contains experimental data from two Cambrian igneous sequences: the approximately 505 Ma Bourinot volcanic rocks of Cape Breton Island, Nova Scotia, Canada, and the approximately 525 Ma Itabaiana mafic dyke swarm of northeastern Brazil. It includes specimen-level paleointensity measurements, paleomagnetic directional data, experiment-step references and file-level metadata. Bourinot samples were analysed using thermal Thellier paleointensity experiments. Itabaiana samples were analysed using thermal and microwave Thellier, modified Shaw, and continuous Triaxe/Wilson methods. The deposited files include upload-ready data for Paleomagnetism.org and Paleointensity.org and supporting files needed to interpret the laboratory treatment steps and directional measurements. The data relate to two study areas: the Bourinot volcanic belt on Long Island, Cape Breton Island, Nova Scotia, eastern Canada; and the Itabaiana mafic dyke swarm in northeastern Brazil, within the Borborema Province. The Bourinot data come from sites BV5, BV7 and BV8, while the Itabaiana data include sites IT1, IT2, IT7 and IT8. These data provide new constraints on Cambrian geomagnetic field strength and were used to show that weak field conditions persisted for tens of millions of years after the Cambrian radiation. The data support the manuscript “Earth’s magnetic field remained weak for 40 million years after the Cambrian radiation” Dr Simon Lloyd University of Liverpool not available originator Dr Rebecca Hopkins University of Liverpool not available originator Enquiries British Geological Survey United Kingdom not available distributor Enquiries British Geological Survey United Kingdom not available pointOfContact notApplicable https://resources.bgs.ac.uk/images/geonetworkThumbs/568f784c-1756-e7a0-e063-3050940af7ef.png Geology GEMET - INSPIRE themes, version 1.0 2008-06-01 publication Geomagnetic fields Magnetism Palaeomagnetism Dyke swarm Geomagnetic reversals Cambrian BGS Thesaurus of Geosciences 2022 revision NGDC Deposited Data Citable Data dataCentre NERC_DDC otherRestrictions licenceOGL Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]" otherRestrictions 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. Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]" English geoscientificInformation 2025-02-07 2026-05-01 csv .txt xlsx th Enquiries British Geological Survey United Kingdom not available distributor https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#item192728 WWW:DOWNLOAD-1.0-http--download Data download https://doi.org/10.5285/34859b8e-0619-4d00-a55d-ff5bc7379a54 WWW:LINK-1.0-http--related Citation Information - Digital Object Identifier (DOI) Lloyd, S., Hopkins, R. (2026). Paleomagnetic and paleointensity data from two Cambrian igneous sequences: 505 Ma Bourinot volcanic rocks of Cape Breton Island, Nova Scotia, Canada, and 525 Ma Itabaiana mafic dyke swarm of northeastern Brazil. NERC EDS National Geoscience Data Centre. (Dataset). https://doi.org/10.5285/34859b8e-0619-4d00-a55d-ff5bc7379a54 information nonGeographicDataset non geographic dataset INSPIRE Implementing rules laying down technical arrangements for the interoperability and harmonisation of Geology 2011 publication See the referenced specification false 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 2010-12-08 publication See http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:323:0011:0102:EN:PDF false Samples with reliable characteristic remanent directions were analysed using palaeomagnetic, rock-magnetic, microscopy and paleointensity methods. Bourinot samples were studied using thermal Thellier experiments with the IZZI+ protocol. Itabaiana samples were analysed using thermal and microwave Thellier, modified Shaw, and continuous Triaxe/Wilson methods. Hysteresis, thermomagnetic magnetisation and susceptibility measurements, scanning electron microscopy and EDX were used to characterise remanence carriers and thermal stability. Thellier-type results were screened using SCOPE, while other results were assessed using method-specific reliability criteria. Only sites consistent with established primary palaeomagnetic populations were retained.