Abstract Extensive facies analysis of the outcrops located near Moscardón (Iberian basin, NE Spain) resulted in a precise reconstruction of the facies architecture of a Bajocian (Middle Jurassic) carbonate platform. Different types of microbialites occurred in the transitional area between the shallow and relatively deep carbonate platform domains, located above and below wave base level, respectively. The most significant volume of the micorbialites is found in the platform slope, located below wave base level, in a depth range of around 30–50 m. In the lower slope, during stages of rapid accommodation gain, the vertical aggradation of individual stratiform building blocks results in the formation of up to 25 m-thick microbial–siliceous sponge buildups. During stages of sea-level highstand the individual building blocks are dominated by lateral (down-slope) progradational accretion, resulting in flatter, lens-shaped buildups. The transition between the upper slope and the shallow platform area is characterized by microbial-encrusted intraclastic–bioclastic packstones. Microbial crust development helped to stabilize the seafloor, allowing the eventual accumulation and preservation of the sand-sized grains above wave base.
The South-Pyrenean Basin (northeastern Spain) has yielded a rich and diverse record of Upper Cretaceous (uppermost Campanian−uppermost Maastrichtian) vertebrate fossils, including the remains of some of the last European dinosaurs prior to the Cretaceous-Paleogene (K-Pg) extinction event. In this work, we update and characterize the vertebrate fossil record of the Arén Sandstone and Tremp formations in the Western Tremp Syncline, which is located in the Aragonese area of the Southern Pyrenees. The transitional and continental successions of these sedimentary units are dated to the late Maastrichtian, and exploration of their outcrops has led to the discovery of numerous fossil remains (bones, eggshells, and tracks) of dinosaurs, including hadrosauroids, sauropods, and theropods, along with other tetrapods such as crocodylomorphs, testudines, pterosaurs, squamates, and amphibians. In particular, this fossil record contains some of the youngest lambeosaurine hadrosaurids (Arenysaurus and Blasisaurus) and Mesozoic crocodylomorphs (Arenysuchus and Agaresuchus subjuniperus) in Europe, complementing the lower Maastrichtian fossil sites of the Eastern Tremp Syncline. In addition, faunal comparison with the fossil record of Hațeg island reveals the great change in the dinosaur assemblages resulting from the arrival of lambeosaurine hadrosaurids on the Ibero-Armorican island, whereas those on Haţeg remained stable. In the light of its paleontological richness, its stratigraphic continuity, and its calibration within the last few hundred thousand years of the Cretaceous, the Western Tremp Syncline is one of the best places in Europe to study the latest vertebrate assemblages of the European Archipelago before the end-Cretaceous mass extinction.
The results o f a sedimentological analysis o f the Carixlan (lower Pliensbachian) o f the northern Iberian Chain (Obon-Castel de Cabra area, Teruel province) are presented in this work. Detailed facies analysis in the Almonacid Unit allowed the paleoenvironmental reconstruction of the carbonate platform developed in the northern part of the Iberian basin. Shall ower areas, located around the Castel de Cabra, were dominated by crinoids, corals and calcareous algae. They were deposited in the transition area between inner and mid ramp environments. In the midramp settings, located to the North (Obon), the facies consists o f marls and bioclastic limestones (mudstone to wackstone), that contain interbedded storm levels (tempestites).