Note on the Alleged Purbeckian at Murzuch, Fezzan, Libya

Abstract

The only fossiliferous representative of the Jurassic system reported to exist in Fezzan (Libya) is the thin freshwater limestone of Murzuch, which is supposed to be Purbeckian. Professor A. Desio (1938) first attributed this deposit to the Mesozoic and dubiously to the Cretaceous, but Pagni (1938) identified from it the Purbeckian gastropod Valvata helicoides Forbes and the Purbeckian plant Chara jaccardi Heer. On the strength of these determinations Professor Desio (1939, 1942) later stated that the Murzuch Limestone “should perhaps be referred to the lacustrine Upper Jurassic (Purbeckian)”. The gastro-pods, as shown in the figures by Pagni, however, do not resemble the true Valvata helicoides de Loriol ex Forbes MS. (refigured Arkell, 1941, p. 89, figs. 14 a, b, 60, 61, 62). During 1950 I pointed this out to Professor Desio. He kindly allows me to record that he as always doubtful about the age of the Murzuch Limestone and that he now considers it to be much younger, perhaps Pliocene.