On the Palaeogene age of some North-Pyrenean and Sub-Pyrenean ''Triasic slices''

Frequent but discontinuous outcrops, exhibiting Triassic lithologies in unusual positions, scatter the North- and Sub-Pyrenean belts. The outcrops being mostly ''out-of-context'', their presence used to be accounted for in the earlier literature through faults, injections along basal overthrust-planes or diapirism, related to the Alpine (Pyrenean) orogenic events. Following the Ypresian age assigned recently to the Caseville (near Bidart on the Basque coast) olistostrome, which consists exclusively of reworked Triassic material, the systematic reexamination and reinterpretation of the set of ''Triassic'' outcrops of this type became a necessity. The lithologies involved consist mainly of variegated: red, pink and white clays and marry limestones, with varying amounts of ophites and carbonates, typical of the Triassic-Jurassic transition. The present work, focused on two additional outcrop-areas, shows that; (a) at Figarol (in the Central Pyrenees), the reddish hemipelagic marry limestones which contain resedimented fine Triassic material and a reworked mixed fauna, are of Thanetian age (zone P4), and that (b) at Lasseube (in the western Pyrenees), the sequence comprising the Triassic elements is composed of a suite of three depositional sequences including a true olistostrome, which belong to the latest Selandian - early Ypresian interval. The Figarol outcrops point out the southeastern most rim of a transgressive event, reaching on to a platform uplifted during the latest Cretaceous movements, while the Lasseube flysch-type sequence belongs to the internal segment of the same Basque-Beam Palaeocene turbidite basin.