Continental deposits around the Cretaceous/Tertiary boundary have been studied for stratigraphy, sedimento/ogy, paleontology and stable isotopes ("C and ,aO) in the Benabarre and Fontllonga sections (Tremp and Ager syndines, 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 ,bO and fall in ,JC) around the K/T boundary is detected. The increase in inO may be linked to higher temperatures and/or to evaporation. The ,3C fall matches the «z event» described in marine environments and interpreted as due to a decrease in marine organic productivity. In non-marine environments however it could indicate an increase in plant productio
