| Título: | Paleomagnetic study of the Messejana Plasencia dyke (Portugaland Spain): A lower Jurassic paleopole for the Iberian plate |
| Autores: | Palencia Ortas, Alicia ; Osete López, María Luisa ; Vegas, Ramón ; Silva , Pedro F. |
| Tipo de documento: | texto impreso |
| Editorial: | Elsevier B.V., 2006 |
| Dimensiones: | application/pdf |
| Nota general: | info:eu-repo/semantics/openAccess |
| Idiomas: | |
| Palabras clave: | Estado = Publicado , Materia = Ciencias: Geología: Geodinámica , Tipo = Artículo |
| Resumen: |
The only Iberian lower Jurassic paleomagnetic pole come from the “Central Atlantic Magmatic Province”-related Messejana Plasencia dyke, but the age and origin of its remanence have been a matter of discussion. With the aim of solving this uncertainty, and to go further into a better understanding of its emplacement and other possible tectonic features, a systematic paleomagnetic investigation of 40 sites (625 specimens) distributed all along the 530 km of the Messejana Plasencia dyke has been carried out. Rock magnetic experiments indicate PSD low Ti-titanomagnetite and magnetite as the minerals carrying the NRM. The samples were mostly thermally demagnetized. Most sites exhibit a characteristic remanent component of normal polarity with the exception of two sites, where samples with reversed polarities have been observed. The paleomagnetic pole derived from a total of 35 valid sites is representative of the whole structure of the dyke, and statistically well defined, with values of PLa=70.4°N, PLo=237.6°E, K=47.9 and A95=3.5°. Paleomagnetic data indicates that: (i) there is no evidence of a Cretaceous remagnetization in the dyke, as it was suggested; (ii) most of the dyke had a brief emplacement time; furthermore, two dyke intrusion events separated in time from it by at least 10,000 y have been detected; (iii) the high grouping of the VGPs directions suggests no important tectonic perturbations of the whole structure of the dyke since its intrusion time; (iv) the pole derived from this study is a good quality lower Jurassic paleopole for the Iberian plate; and (v) the Messejana Plasencia dyke paleopole for the Iberian plate is also in agreement with quality-selected European and North American lower Jurassic paleopoles and the magnetic anomalies data sets that are available for rotate them to Iberia. |
| En línea: | https://eprints.ucm.es/id/eprint/16745/1/1-s1971.pdf |
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