Sedimentary evolution of an aptian syn-rift carbonate system (Maestrat basin, E Spain): Effects of accommodation and environmental change

We report an integrated study of an expanded and relatively complete syn-rift continental to epeirie marine sue- cession of Aptian age, cropping out in the western Maestrat Basin (eastern Iberian Chain), Four transgrcssive- regressive sequences are recognized throughout this mixed carbonate-siliciclastic succession, with excellent age control provided by ammonite bioslratigraphic data. The transgrcssive systems tracts consist mainly of alterna- tions of marls and limestones rich in orbitolinids. The regressive systems tracts arc essential!;' characterized by wave- and lidally influenced siliciclastic and carbonate deposits, and by the development of carbonate platforms with rudists, corals, orbitolinids and green algae. Carbon and oxygen isotope curves were established in order to identify the global δ13C perturbations related to the 1 iarly Aptian Oceanic Anoxic I ivent (OAHla). These perturba- tions commence with a horizon of coral rubble encrusted by Lñhocodiwn aggregation and Bacinella irregularis with widespread large-sized discoidal Palorbilolina lenticularis. Associated δ18O values indicate high-frequency cooling-warming climatic cycles. The fault-controlled rapid syn-rift subsidence recorded during this stage was the most important factor in producing accommodation. However, the major transgressions, sea level falls and biotic changes recorded in the eastern Iberian Chain arc in agreement with those registered in other contemporaneous basins of the Tethys. Thus, the resulting sedimentary succession faithfully reflects the major océanographie and climatically-driven global changes that characterized this stage albeit within a context established by regional tectonics. I Ience, this well-documented record of the evolution of an Aptian epicontinental sea provides a useful comparative case study for the analysis of other Aptian epeirie sedimentary successions.