Estudio paleomagnético del dique de Messejana-Plasencia

Abstract

A paleomagnetic investigation of 39 sites (591 samples) across the 530 km ot the Messejana-Plasenciadike has been carried out. Rock magnetic experiments indicate PSD low Ti titanomagnetite and magnetite as the minerals carrying the NRM. The samples where mostly demagnetised by thermal demagnetisation. 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 the sites is well defined, with values ot Plat=70.5, Plong=238.0, K= 47.8 and ags=3.5. Paleomagnetic data indicates: (i) the dike had a brief emplacement time, (ii) the age of intrusion can be constrained between 180-200 Ma, (Hi) the high grouping of the VGPs directions suggest no important tectonic perturbations of the whole structure of the dike since its intrusion to the present.