THE AS FORMATION, DATED OLIGOCENE, IS INV OLVED IN THE THRUSTING OF THE UPPER MALAGUIDE UNITS IN THE SIERRA ESPUNA (BETIC INTERNAL ZONES, PROV. OF MURCIA, SPAIN)

The mapping, lithostratigraphical analysis and palaeontological dating of the Tertiary formations of the Malaguide Complex in Sierra Espuna allow us to define the As Formation and to recognize its tectonic posi tion. This formation is made of conglomerates, sandstones and lithocla stic limestones, mainly characterized by the generalized presence of r ounded pebbles of quartz and was deposited in shallow-water, coastal s ettings. This formation, interpreted before as post-tectonic and of Eo cene age ('Auversion'), has been dated as late Lower Oligocene-early U pper Oligocene. Its deposition predates nappe emplacement in the area because it is widely overthrusted under the Mesozoic rocks of the Uppe r Malaguide nappe of Perona.