2026-05-11T12:47:40Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/111982026-01-13T01:05:37Zcom_10259.4_2560com_10259_5086com_10259_2604col_10259.4_2561

Calvo Rathert, Manuel 93 600 0000-0001-9977-0192 Carrancho Alonso, Ángel 104 600 0000-0001-7119-6424 Morales Montor, Jorge f39689d5-eb9d-4916-8b78-c4d46e1e2228 600 Pérez Rodríguez, Noelia 9a561deb-8f49-4b5f-9d2b-b6216a4395ef 600 Lebedev, Vladimir A. 7692207d-596f-4ce7-addb-db244832a4e8 600 Caccavari, Ana eb5762ef-907c-4e4d-8a2c-4fd822a46361 600 Goguitchaichvili, Avto 978a6f31-eb60-48af-9711-af15682307d5 600 2026-01-12T12:34:27Z 2026-01-12T12:34:27Z 2022-10 0956-540X https://hdl.handle.net/10259/11198 10.1093/gji/ggac173 1365-246X We present new radiometric ages and full-vector palaeomagnetic data from São Vicente Island, Cape Verde. Samples were obtained from a sequence of 11 flows. A K-Ar age determination was performed on the lowermost flow of the sequence, yielding an upper Miocene age of 6.07 ± 0.16 (2σ) Ma. Considering the normal polarity observed in all flows, the age of the sequence could be narrowed down to an interval between 6.03 and 6.23 Ma. The mean palaeomagnetic direction of the studied sequence was compared with the expected direction, calculated from the African Apparent Polar Wander Path (5 Ma). While inclinations approximately agree, the palaeodeclination appears westwardly deviated by 26.5° ± 2.9°. Moreover, nearly no scatter of virtual geomagnetic poles around their mean value is observed and its comparison with the scatter observed in palaeomagnetic directions obtained from geomagnetic field model SHA.DIF.14k suggests that the sequence was very rapidly emplaced in only a few centuries. Thus, the obtained anomalous palaeomagnetic direction seems to reflect the effect of non-averaged secular variation, although a local vertical-axis counter-clockwise rotation of the sequence, cannot be entirely ruled out. Thellier–Coe palaeointensity experiments on 66 specimens yielded 22 successful determinations and multispecimen (MS) palaeointensity experiments on 11 samples yielded 8 successful determinations. In the upper part of the sequence, Thellier–Coe determinations fail due to the presence of multidomain (MD) grains, but the MS method yields successful results in several of these flows, demonstrating that this method can provide reliable palaeointensity determinations on samples with a higher MD grain fraction. A mean palaeointensity BSV = (18.5 ± 1.9) µT is obtained from the joint analysis of the results from both methods. This value lies clearly below the present-day value BP = 33.1 μT. The virtual axial dipole moment (VADM = 4.3 × 1022 Am2), however, cannot be considered anomalous if compared to available upper Miocene–Pliocene data and represents a new high-reliability contribution to the very limited African palaeointensity database. This work was funded by project PID2019-105796GB-100/AEI/10.13039/501100011033 (Spanish Agencia Estatal de Investigación). application/pdf eng Oxford University Press Geophysical Journal International. 2022, V. 231, n. 1, p. 215-229 https://doi.org/10.1093/gji/ggac173 Paleomagnetism Paleointensity Rock magnetism Paleomagnetic secular variation Africa Paleomagnetismo Geología histórica Paleomagnetism Historical geology Multimethod palaeointensity results from a rapidly emitted upper Miocene lava flow sequence in São Vicente (Cape Verde): new data for the African record info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion info:eu-repo/semantics/openAccess Geophysical Journal International 231 1 215 229 THUMBNAIL Calvo-gji_2022.pdf.jpg Calvo-gji_2022.pdf.jpg IM Thumbnail image/jpeg 3669 https://riubu.ubu.es/bitstream/10259/11198/3/Calvo-gji_2022.pdf.jpg 6ddaa5f8031048ea4aa5f287c1f38111 MD5 3 LICENSE license.txt license.txt text/plain; charset=utf-8 999 https://riubu.ubu.es/bitstream/10259/11198/2/license.txt b295bcbce42e2caabeb0c623d3860c06 MD5 2 ORIGINAL Calvo-gji_2022.pdf Calvo-gji_2022.pdf application/pdf 6453959 https://riubu.ubu.es/bitstream/10259/11198/1/Calvo-gji_2022.pdf 20dfd221331ddfcee964df88d4ec2054 MD5 1 10259/11198 oai:riubu.ubu.es:10259/11198 2026-01-13 02:05:37.602 Repositorio Institucional de la Universidad de Burgos bubrep@ubu.es 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