Primeros resultados magnetoestratigráficos del Triásico Medio­ Superior (Ladiniense-Karniense) en la Cordillera Ibérica occidental (Cuevas de Ayllón) First magnetostratigraphic resu/ts of the Middle-Late Triassic (Ladinian-Carnian) in the westem Iberian Ranges (Cuevas de Ay/Ión)

A magnetostratigraphic investigation on a Middle-Late Triassic section outcropping at Cuevas de Ay/Ion (westernmost margin of the !herian Ranges, Spain) has been performed. The section most1y consists of a thick sequence of interbedded mudstones and sandstones. The age of the sampled formation has been established as Ladinian-Karnian on the basis of palynological assemblages. 123 samples were subjected toa progressive thermal demagnetization up to 680 o C. A multicomponent magnetization behaviour has been observed. The characteristic component cou/d be iso/ated from 575-620 oC up to 680 oC, in 74 samples showed both polarities and allowed to define a consistent magnetic zonation. The data presented wi/1 contribute to the construction of a standard polarity sea/e for the Triassic time span.