Magnetoestratigrafía del Neógeno del sector central de la Cuenca del Duero

Abstract

Several biostratigraphic studies have been carried out on lacustrine and fluvial-lacustrine sediments in the neogene Duero Basin, these show that most of the outcrop depositional sequence belongs to the Aragonian - Upper Vallesian. Howewer, the age of neogene sedimentary infill is still unknown. For this reason, a magnetostratigraphic study have been carried out on four sites (Torremormojón, Jariego de Cerrato, Tortoles de Esgueva y La Miranda) in order to stabllsh magnetostratigraphic correlations between them. Samples were step-wise thermally demagnetized, susceptibility was measured after each heating step, and experiments of incremental acquisition of isothermal remanence were carried out. Samples present a low intensity of the natural remanent magnetization (NRM) and viscous and / or chemical secondary components. In spite of this, most of the cases the polarity of the primary component has been identified and the tale magnetostratigraphic logs have been obtained in each site. These logs have been correlated with the geomagnetic polarity timescale, and some magnetozones have been dated. The investigated sediments.have an age ranging from 7.3 to 11.4 m.a.