Asociaciones de ostrácodos continentales de la Fm. Aguilar (Jurásico superior-Cretácico inferior, Cuenca Vascocantábrica)

Abstract

The fossiliferous content of the Aguilar Fm. (latest Jurassic-earliest Cretaceous, Bascocantabrian Basin, N. Spain) consist mostly of ostracods, clavatoraceans, porocharaceans and gastropods, plus minor remains of fishes, crocodiles and turtles, a typical association of lacustrine palaeoenvironment. The preliminary analysis of the ostracod assemblages further suggests that (i) the bulk of the unit was deposited during the Jurassic (late Portlandian) and (ii) that salinity variations took place during the evolution of the lacustrine system. Thus, the environment was fresh-water during most of the Portlandian, changing to oligohaline conditions at the end of the Jurassic. A more pronounced change took place during the lowest Cretaceous, when the main water mass became slightly saline, with euryhaline conditions occurring in marginal areas of the lake