Transición Cretácico/Terciario en depósitos continentales de la cuenca de Tremp-Graus: datos preliminares de isótopos estables de CyO

Abstract

Continental deposits around the CretaceouslTertiary boundary have been studied for stratigraphy, sedimentology, paleontology and stable isotopes (JJC and 180) in the Benabarre and Fontlfonga sections (Tremp and Ager synclines, Southern Pyrenees). Similarities in lithology, sedimentary evolution, fossil content and isotopic values allow us to interpret these deposits as part of a single basin. A shift in the isotopic content (rise in 180 and fall in 13C) around the KIT boundary is detected. The in creas e in 180 may be Iinked to higher temperatures andlor to evaporation. The 13e falf matches the «z event» described in marine environments and interpreted as due to a decrease in marine organic productivity. In nonmarine environments however it could indicate an increase in plant production.