%0 Journal Article
%A Palencia Ortas, Alicia
%A Osete López, María Luisa
%A Vegas Martínez, Ramón
%A Silva , Pedro F.
%T Paleomagnetic study of the Messejana Plasencia dyke (Portugaland Spain): A lower Jurassic paleopole for the Iberian plate
%D 2006
%@ 0040-1951
%U https://hdl.handle.net/20.500.14352/50143
%X The only Iberian lower Jurassic paleomagnetic pole come from the “Central Atlantic Magmatic Province”-related MessejanaPlasencia 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 paleomagneticinvestigation 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 sampleswere mostly thermally demagnetized. Most sites exhibit a characteristic remanent component of normal polarity with the exceptionof two sites, where samples with reversed polarities have been observed. The paleomagnetic pole derived from a total of 35 validsites 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 itwas suggested; (ii) most of the dyke had a brief emplacement time; furthermore, two dyke intrusion events separated in time from itby at least 10,000 y have been detected; (iii) the high grouping of the VGPs directions suggests no important tectonic perturbationsof the whole structure of the dyke since its intrusion time; (iv) the pole derived from this study is a good quality lower Jurassicpaleopole for the Iberian plate; and (v) the Messejana Plasencia dyke paleopole for the Iberian plate is also in agreement withquality-selected European and North American lower Jurassic paleopoles and the magnetic anomalies data sets that are availablefor rotate them to Iberia.
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