RT Journal Article
T1 Paleomagnetic study of the Messejana Plasencia dyke (Portugaland Spain): A lower Jurassic paleopole for the Iberian plate
A1 Palencia Ortas, Alicia
A1 Osete López, María Luisa
A1 Vegas Martínez, Ramón
A1 Silva, Pedro F.
AB 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.
PB Elsevier B.V.
SN 0040-1951
YR 2006
FD 2006
LK https://hdl.handle.net/20.500.14352/50143
UL https://hdl.handle.net/20.500.14352/50143
LA eng
DS Docta Complutense
RD 10 ago 2024