Latest Cretaceous palaeogeographic evolution of northeast Iberia: Insights from the Campanian continental Montalbán subbasin (Spain)

Abstract

This work characterizes for the first time the 500–700 m-thick uppermost Cretaceous continental sedimentarysuccession of the Allueva Fm recorded in the northeastern margin of the Iberian basin, in the Montalb´an subbasin(Maestrazgo domain, Spain). The middle-upper Campanian age of this unit constrained here by new paleomagneticand biostratigraphic data involves major revision of previous stratigraphic and palaeogeographic interpretations.The uplift of the northern marginal areas of the Montalb´an subbasin onwards from the middleCampanian supplied the coarse terrigenous-clastic sediments common in the alluvial Allueva Fm. Moreover, asharp increase of the sedimentation rates (from 4 to 19 cm/ky) from the lower to the middle-upper part of theAllueva Fm has been related to further increase of the tectonic activity during the middle part of the lateCampanian. Also relevant are the new discovered vertebrate sites mostly found in the marginal areas of a largelacustrine-palustrine carbonate system developed during the latest Campanian. Vertebrate sites include a fossilassemblage with abundance of titanosaur sauropod dinosaurs as well as the presence of ornithopod dinosaursand crocodylomorphs. A review of the dinosaur fossil sites recorded in other Iberian subbasins shows a similarfossil assembage occurrence during the late Campanian–earliest Maastrichtian timespan, previous to the faunalturnover that took place in the Ibero-Armorican landmass around the onset of the late Maastrichtian. Thestratigraphic, sedimentological and paleontological characterization of the successions recorded during theinitial stages of development of the Montalb´an subbasin have major implication to understand the latestCretaceous palaeogeographic evolution of northeast Iberia. Comparative review to other latest Cretaceouscontinental successions deposited in other domains of the Iberian basin indicates a south to north migration ofnewly developed subsident subbasins: during the Campanian (South Iberian domain), during the middle-lateCampanian (northern Maestrazgo domain), and during the Maastrichtian (central Castillian domain).