Registros magnetoestratigráficos de alta resolución: evidencia del subcron C5Dr.1n en el Mioceno inferior de la Cuenca del Ebro

A high-resolution magnetostratigraphic study in the Miocene sediments of the Ebro Basin providesfurther support for the existence of subchron C5Dr.1n. This normal polarity short event was firstrecognised in the North Pacific magnetic anomaly stack, but was relegated to cryptochron status inthe most recent Geomagnetic Polarity Time Scales. Based on previous magnetostratigraphic studies, a detailed sampling focused on a stratigraphic interval where presence of a short normal polarity event within C5Dr was suspected in the Lanaja Section (Ebro Basin) has been accomplished.Samples were collected every 10 cm along an interval of 5 meters and paleomagnetic analysis revealed the existence of a true normal polarity magnetozone of about 50 Ka of duration at anapproximate age of 17.8 Ma. The same event has been recently recorded in sediments of the ODPSite 1090 in the Southern Atlantic thus providing robust evidence that it corresponds to a true geomagnetic subchron.