El límite de las Biozonas Transversarium y Bifurcatus (Oxfordiense Medio) en la Cordillera Ibérica nororiental: discontinuidades y lagunas estratigráficas asociadas

Abstract

A biostratigraphic study of Middle Oxfordian, Transversarium to Bifurcatus Zone rocks in the northeastern Iberian Chain (Spain) has been taken along six detailed sections providing very close ammonite control. The deposition takes place in a uniform carbonate ramp dominated by sponge limestone facies in the western part grading into glauconitic fades in the eastern, distal part. The study shows that, despite the homogeneity of the ramp and general isochrony of the facies, the sedimentation was highly irregular with important discontinuities separating the successive biostratigraphic units. A palaeogeographic separation in the ramp appears possible into a Western, slightly more subsident area and an eastern, external part where stratigraphic and taphonomic condensation values reached a maximum during this interval