S'ALBUFERETA DE POLLENÇA (MALLORCA): UNA INTRODUCCIÓ A LA SEVA GEOMORFOLOGIA I L'EVOLUCIÓ SEDIMENTÀRIA RECENT.

The Albufereta de Pollença is located in the north of the island of Mallorca, at the southernmost end of the bay of Pollença. The Albufereta is a coastal lagoon, with an extension of 400 ha, which structurally occupies a post-Miocene depression resulting from the distensive extension that took place after the formation of the Serra de Tramuntana at the end of the Oligocene-Lower Miocene. A coring campaign, as well as geomorphological mapping, allows the description of the morphological elements and the different sedimentary sub-environments present in the Holocene archives of this area. The coastal lagoon consists of an area of ponds and coastal lakes furrowed by a series of channels, which are separated from the sea by a sandy barrier, which currently connects with the sea by a single inlet. Locally the barrier exhibit signs of recession. Regarding to the Holocene sedimentary fill, it does not acquire a remarkable thickness, from 3 to 5 m core depths, resting on the Jurassic basement or on the Miocene marls. Detrital silty facies predominate, partially sandy and with occasional contributions of gravel, reddish in colour; which indicates that the filling of the area is mainly due to the alluvial contributions associated with the streams. The nature and thickness of the record indicate that the Holocene transgression did not exceed the height of the meter with respect to the current sea level, and that the subsidence is not very important in this area. Logs and sedimentary facies indicate that during the Holocene transgression the paleotopography inherited from the last glacial period was replenished. [ABSTRACT FROM AUTHOR]