An integrated palaeomagnetic, palaeointensity and 40Ar/39Ar investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands
A detailed palaeomagnetic, rock-magnetic and palaeointensity study has been carried out on a Miocene volcanic sequence which consists of 39 consecutive lava flows recording a polarity transition in La Gomera (Canary Islands, Spain). In addition, new 40Ar/39Ar ages were obtained in two flows, yieldin...
Published in: | Geophysical Journal International |
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Oxford University Press
2015
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Online Access: | http://hdl.handle.net/10261/180059 https://doi.org/10.1093/gji/ggu481 https://doi.org/10.13039/501100003329 https://doi.org/10.13039/501100000780 https://doi.org/10.13039/501100004837 https://doi.org/10.13039/501100003141 |
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ftcsic:oai:digital.csic.es:10261/180059 2024-06-23T07:52:58+00:00 An integrated palaeomagnetic, palaeointensity and 40Ar/39Ar investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands Caccavari, Anna Calvo-Rathert, Manuel Goguitchaichvili, Manuel Soler, Vicente Huaiyu, He Vegas, Néstor European Commission Ministerio de Ciencia e Innovación (España) Ministerio de Economía y Competitividad (España) Consejo Nacional de Ciencia y Tecnología (México) 2015-03 http://hdl.handle.net/10261/180059 https://doi.org/10.1093/gji/ggu481 https://doi.org/10.13039/501100003329 https://doi.org/10.13039/501100000780 https://doi.org/10.13039/501100004837 https://doi.org/10.13039/501100003141 unknown Oxford University Press Publisher's version https://doi.org/10.1093/gji/ggu481 Sí doi:10.1093/gji/ggu481 issn: 0956-540X e-issn: 1365-246X Geophysical Journal International 200(3): 1297-1316 (2014) http://hdl.handle.net/10261/180059 http://dx.doi.org/10.13039/501100003329 http://dx.doi.org/10.13039/501100000780 http://dx.doi.org/10.13039/501100004837 http://dx.doi.org/10.13039/501100003141 open Palaeomagnetic secular variation Rock and mineral magnetism Palaeointensity Reversals: process time scale Magnetostratigraphy artículo http://purl.org/coar/resource_type/c_6501 2015 ftcsic https://doi.org/10.1093/gji/ggu48110.13039/50110000332910.13039/50110000078010.13039/50110000483710.13039/501100003141 2024-05-29T00:00:47Z A detailed palaeomagnetic, rock-magnetic and palaeointensity study has been carried out on a Miocene volcanic sequence which consists of 39 consecutive lava flows recording a polarity transition in La Gomera (Canary Islands, Spain). In addition, new 40Ar/39Ar ages were obtained in two flows, yielding 9.63 ± 0.06 Ma in the lower and 9.72 ± 0.08 Ma in the upper part of the sequence. Palaeomagnetic results allowed determining a ChRM direction in all studied lavas: The 25 lowermost flows of the sequence display normal polarity directions and above, a sequence of 14 flows correspond to a transitional geomagnetic regime. If considered together with palaeomagnetic results from a previous study, which were obtained on the flows immediately overlying the upper part of the sequence analysed in this work, these results indicate that the reversal recorded in the Hermigua sequence corresponds to the normal to reverse C4Ar2n to C4Ar3r polarity transition. The lower-lying 25 normal-polarity flows yield a mean direction D = 359.6°, I = 42.4° (α95 = 5.1°; k = 33) which agrees well with the expected values. Above, a sequence of 14 flows displays a more irregular directional behaviour, including several transitional directions, suggesting the occurrence of a precursor to the transition. The presence of a virtual geomagnetic pole (VGP) cluster in the western Atlantic Ocean observed in this study coincides with previous records of Miocene transitions. Interestingly, this region corresponds to a near-radial flux centre of the present-day non axial dipole field. Angular dispersion of VGPs calculated for the 25 lowermost normal polarity flows of the sequence shows a lower than expected result. Palaeointensity determinations were carried out using a Thellier type double heating method. 27 of the 48 analysed samples measured yielded successful results. Mean VDMs mean values range from 1.1 ± 0.5 to 8.8 ± 0.9 × 1022 Am2. The intensity values decrease significantly on approaching the directional transitional zone, suggesting an earlier ... Article in Journal/Newspaper Geomagnetic Pole Digital.CSIC (Spanish National Research Council) Geophysical Journal International 200 3 1297 1316 |
institution |
Open Polar |
collection |
Digital.CSIC (Spanish National Research Council) |
op_collection_id |
ftcsic |
language |
unknown |
topic |
Palaeomagnetic secular variation Rock and mineral magnetism Palaeointensity Reversals: process time scale Magnetostratigraphy |
spellingShingle |
Palaeomagnetic secular variation Rock and mineral magnetism Palaeointensity Reversals: process time scale Magnetostratigraphy Caccavari, Anna Calvo-Rathert, Manuel Goguitchaichvili, Manuel Soler, Vicente Huaiyu, He Vegas, Néstor An integrated palaeomagnetic, palaeointensity and 40Ar/39Ar investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands |
topic_facet |
Palaeomagnetic secular variation Rock and mineral magnetism Palaeointensity Reversals: process time scale Magnetostratigraphy |
description |
A detailed palaeomagnetic, rock-magnetic and palaeointensity study has been carried out on a Miocene volcanic sequence which consists of 39 consecutive lava flows recording a polarity transition in La Gomera (Canary Islands, Spain). In addition, new 40Ar/39Ar ages were obtained in two flows, yielding 9.63 ± 0.06 Ma in the lower and 9.72 ± 0.08 Ma in the upper part of the sequence. Palaeomagnetic results allowed determining a ChRM direction in all studied lavas: The 25 lowermost flows of the sequence display normal polarity directions and above, a sequence of 14 flows correspond to a transitional geomagnetic regime. If considered together with palaeomagnetic results from a previous study, which were obtained on the flows immediately overlying the upper part of the sequence analysed in this work, these results indicate that the reversal recorded in the Hermigua sequence corresponds to the normal to reverse C4Ar2n to C4Ar3r polarity transition. The lower-lying 25 normal-polarity flows yield a mean direction D = 359.6°, I = 42.4° (α95 = 5.1°; k = 33) which agrees well with the expected values. Above, a sequence of 14 flows displays a more irregular directional behaviour, including several transitional directions, suggesting the occurrence of a precursor to the transition. The presence of a virtual geomagnetic pole (VGP) cluster in the western Atlantic Ocean observed in this study coincides with previous records of Miocene transitions. Interestingly, this region corresponds to a near-radial flux centre of the present-day non axial dipole field. Angular dispersion of VGPs calculated for the 25 lowermost normal polarity flows of the sequence shows a lower than expected result. Palaeointensity determinations were carried out using a Thellier type double heating method. 27 of the 48 analysed samples measured yielded successful results. Mean VDMs mean values range from 1.1 ± 0.5 to 8.8 ± 0.9 × 1022 Am2. The intensity values decrease significantly on approaching the directional transitional zone, suggesting an earlier ... |
author2 |
European Commission Ministerio de Ciencia e Innovación (España) Ministerio de Economía y Competitividad (España) Consejo Nacional de Ciencia y Tecnología (México) |
format |
Article in Journal/Newspaper |
author |
Caccavari, Anna Calvo-Rathert, Manuel Goguitchaichvili, Manuel Soler, Vicente Huaiyu, He Vegas, Néstor |
author_facet |
Caccavari, Anna Calvo-Rathert, Manuel Goguitchaichvili, Manuel Soler, Vicente Huaiyu, He Vegas, Néstor |
author_sort |
Caccavari, Anna |
title |
An integrated palaeomagnetic, palaeointensity and 40Ar/39Ar investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands |
title_short |
An integrated palaeomagnetic, palaeointensity and 40Ar/39Ar investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands |
title_full |
An integrated palaeomagnetic, palaeointensity and 40Ar/39Ar investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands |
title_fullStr |
An integrated palaeomagnetic, palaeointensity and 40Ar/39Ar investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands |
title_full_unstemmed |
An integrated palaeomagnetic, palaeointensity and 40Ar/39Ar investigation on a Miocene polarity transition recorded in a lava sequence in la Gomera, Canary Islands |
title_sort |
integrated palaeomagnetic, palaeointensity and 40ar/39ar investigation on a miocene polarity transition recorded in a lava sequence in la gomera, canary islands |
publisher |
Oxford University Press |
publishDate |
2015 |
url |
http://hdl.handle.net/10261/180059 https://doi.org/10.1093/gji/ggu481 https://doi.org/10.13039/501100003329 https://doi.org/10.13039/501100000780 https://doi.org/10.13039/501100004837 https://doi.org/10.13039/501100003141 |
genre |
Geomagnetic Pole |
genre_facet |
Geomagnetic Pole |
op_relation |
Publisher's version https://doi.org/10.1093/gji/ggu481 Sí doi:10.1093/gji/ggu481 issn: 0956-540X e-issn: 1365-246X Geophysical Journal International 200(3): 1297-1316 (2014) http://hdl.handle.net/10261/180059 http://dx.doi.org/10.13039/501100003329 http://dx.doi.org/10.13039/501100000780 http://dx.doi.org/10.13039/501100004837 http://dx.doi.org/10.13039/501100003141 |
op_rights |
open |
op_doi |
https://doi.org/10.1093/gji/ggu48110.13039/50110000332910.13039/50110000078010.13039/50110000483710.13039/501100003141 |
container_title |
Geophysical Journal International |
container_volume |
200 |
container_issue |
3 |
container_start_page |
1297 |
op_container_end_page |
1316 |
_version_ |
1802644437942140928 |