An Approach to the Geological Context of the New and Exceptional Upper Cretaceous Paleontological Site of "Lo Hueco", Spain

In 2007, the paleontological site of "Lo Hueco" was discovered in the locality of Fuentes, Cuenca, Spain. At present, more than 8000 fossil remains (mainly saurischian and ornithischian dinosaurs, crocodiles, turtles and fishes) have been recovered in this new and exceptional outcrop, which composes one of the most important collections into the Iberian and the European record of Upper Cretaceous macrovertebrates (Ortega et al., 2008). "Lo Hueco" includes, in "Garumnian" facies, a stratigraphic interval that corresponds to the upper part of the Villalba de la Sierra Formation (Vilas et al., 1982). This lithostratigraphic unit comprises from lower Campanian to middle Eocene materials (Gil et al., 2004).

In the studied paleontological site it can be observed a succession of green (V), grey (G1), red (R1), grey (G2), red (R2) and brown (M) stratigraphic levels of marly mudstones, separated by progressive boundaries. This succession becomes partially modified by a sandy channel structure (C) that interrupts the V, G1 and R1 levels by an erosive surface, and by a sulphated interval (S) that distorts, at least, the G2 level. The C structure and the G1, G2 and R2 (lower part) levels have an extremely rich and varied fossil accumulation.

The relative stratigraphical position and the paleontological content of "Lo Hueco" indicate that it could be attributed to the late Campanian-early Maastrichtian interval. The interpretation of its facies suggests a transitional brackish water to continental fresh water environment exposed to intermittent high to low energy intervals in the relatively arid and regressive global context of the Late Cretaceous.

Acknowledgements: ADIF, Junta de Castilla-La Mancha and research project PAI08-0204-1312.

References: Gil et al., 2004. Revista de la Sociedad Geológica de España, 17: 249-266.

Ortega et al., 2008. Palaeontologica Nova, 8: 119-131.

Vilas et al., 1982. In García (Ed.). Universidad Complutense de Madrid: 457-508.