Isotopic indices (C-13 and O-18) of an important cooling at the end of thePliocene (Puimoisson lacustrine formation, Alpes-de-Haute-Provence, France)

The available sedimentological data in the Plio-Pleistocene series of Puimo isson are compared with the results of the study of stable isotopes (C-13 a nd O-18). During a great part of the Pliocene (4-2 Ma), isotopic variations relate to simple fluctuations of the lake level. At the end of the Pliocen e, a considerable and durable enrichment of both isotopes occurred. This ch ange, due to a great decrease in temperature in the basin, could correspond with the first deterioration of the global climate and also with the uplif t of alpine are at the end of Neogene tecto-orogenesis. ((C) Academie des s ciences / Elsevier, Paris.).