Floor-age constraining of a tectonic paroxysm of the Pyrenean orogen. LateMiddle Eocene mammal age of a faulted karstic filling of the Quercy phosphorites, south-western France

Breaking effects of a Pyrenean compressive tectonic phase are recognised in northern Pyrenean foreland, such as in the Quercy Jurassic limestone platf orm. The age of this phase still remains poorly constrained. In the so-call ed Quercy phosphorites area, within the Prajoux-Memerlin paleokarst system near the city of Cajarc, a clay filling shows a strike slip fault effect. c lose to N-S direction. According to an analysis of the mammal fauna and inf erred chronology of the polyphased paleokarst infilling, the age of the fau lted clay is late Middle Eocene, with a mammal age estimate of 31.5 Ma. Thi s provides reliable precise Boor-age constraining for the involved sismo-te ctonic paroxysm, seemingly related to the Pyrenean tectonic compressive pha se. (C) 2000 Editions scientifiques ct medicales Elsevier SAS.