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Palaeomagnetic study of a subaerial volcanic ridge (São Jorge Island, Azores) for the cobb mountain subhron, volcano flank instability and tectonomagmatic implications

2012-03Journal article Restricted access
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dc.contributor.authorSilva, P. F.
dc.contributor.authorHenry, B.
dc.contributor.authorMarques, Fernando O.
dc.contributor.authorHildenbrand, A.
dc.contributor.authorMadureira, P.
dc.contributor.authorMeriaux, C. A.
dc.contributor.authorKratinova, Z.
dc.date.accessioned2015-08-28T15:17:22Z
dc.date.available2015-08-28T15:17:22Z
dc.date.issued2012-03
dc.description.abstractWe present a palaeomagnetic study on 38 lava flows and 20 dykes encompassing the past 1.3 Myr on S. Jorge Island (Azores ArchipelagoNorth Atlantic Ocean). The sections sampled in the southeastern and central/western parts of the island record reversed and normal polarities, respectively. They indicate a mean palaeomagnetic pole (81.3 degrees N, 160.7 degrees E, K= 33 and A95= 3.4 degrees) with a latitude shallower than that expected from Geocentric Axial Dipole assumption, suggesting an effect of non-dipolar components of the Earth magnetic field. Virtual Geomagnetic Poles of eight flows and two dykes closely follow the contemporaneous records of the Cobb Mountain Subchron (ODP/DSDP programs) and constrain the age transition from reversed to normal polarity at ca. 1.207 +/- 0.017 Ma. Volcano flank instabilities, probably related to dyke emplacement along an NNWSSE direction, led to southwestward tilting of the lava pile towards the sea. Two spatially and temporally distinct dyke systems have been recognized on the island. The eastern is dominated by NNWSSE trending dykes emplaced before the end of the Matuyama Chron, whereas in the central/western parts the eruptive fissures oriented WNWESE controlled the westward growth of the S. Jorge Island during the Brunhes Chron. Both directions are consistent with the present-day regional stress conditions deduced from plate kinematics and tectonomorphology and suggest the emplacement of dykes along pre-existing fractures. The distinct timing and location of each dyke system likely results from a slight shift of the magmatic source.por
dc.identifier.doi10.1111/j.1365-246X.2011.05320.x
dc.identifier.issn0956-540X
dc.identifier.urihttp://hdl.handle.net/10400.21/5045
dc.language.isoporpor
dc.peerreviewedyespor
dc.publisherWiley-Blackwellpor
dc.relationPOCTI/CTE/48137/2002
dc.relationEVOLV - Evolution of Linear Volcanic ridges in Central Azores: interaction between magmatic and tectonic processes.
dc.subjectPalaeomagnetic Secular Variationpor
dc.subjectPalaeomagnetism Applied to Tectonicspor
dc.subjectPalaeomagnetism Applied to Geologic Processespor
dc.subjectReversalspor
dc.subjectProcesspor
dc.subjectTime Scalepor
dc.subjectMagnetostratigraphypor
dc.subjectRock and Mineral Magnetismpor
dc.subjectAtlantic Oceanpor
dc.titlePalaeomagnetic study of a subaerial volcanic ridge (São Jorge Island, Azores) for the cobb mountain subhron, volcano flank instability and tectonomagmatic implicationspor
dc.typejournal article
dspace.entity.typePublication
oaire.awardTitleEVOLV - Evolution of Linear Volcanic ridges in Central Azores: interaction between magmatic and tectonic processes.
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/5876-PPCDTI/PTDC%2FCTE-GIN%2F71838%2F2006/PT
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/3599-PPCDT/PTDC%2FCTE-GIX%2F108149%2F2008/PT
oaire.citation.endPage978por
oaire.citation.issue3por
oaire.citation.startPage959por
oaire.citation.titleGeophysical Journal Internationalpor
oaire.citation.volume188por
oaire.fundingStream5876-PPCDTI
oaire.fundingStream3599-PPCDT
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.nameFundação para a Ciência e a Tecnologia
project.funder.nameFundação para a Ciência e a Tecnologia
rcaap.rightsclosedAccesspor
rcaap.typearticlepor
relation.isProjectOfPublicationbb74a6e0-47aa-446d-b84b-355c343db4d2
relation.isProjectOfPublication181601ab-5b60-48d7-9df5-b33e13f27112
relation.isProjectOfPublication.latestForDiscoverybb74a6e0-47aa-446d-b84b-355c343db4d2

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