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

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”

Date (Creation): 2026-07-10

Citation identifier: http://data.bgs.ac.uk/id/dataHolding/13608743

Point of contact

Organisation name	Individual name	Electronic mail address	Role
University of Liverpool	Dr Simon Lloyd	not available	Originator
University of Liverpool	Dr Rebecca Hopkins	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

Geomagnetic fields
Magnetism
Palaeomagnetism
Dyke swarm
Geomagnetic reversals
Cambrian

dataCentre

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: 2025-02-07

End date: 2026-05-01

Reference System Information

No information provided.

Distribution format

Name	Version
csv
.txt
xlsx
th

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#item192728	Data

OnLine resource

Protocol	Linkage	Name
WWW:LINK-1.0-http--related	https://doi.org/10.5285/34859b8e-0619-4d00-a55d-ff5bc7379a54	Citation Information - Digital Object Identifier (DOI)

Hierarchy level: Non geographic dataset

Other: non geographic 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: 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.