Cambios en la dinámica litoral y nivel del mar durante el Holoceno en el Sur de Iberia y Canarias Orientales

Abstract

The interaction between global factors ("global" glacio-eustatic sea-level rise) and regional factors (tectonic trend, oceanographic factor) is analyzed in different areas of the Iberian and Canary Island littoral. Sea-level changes and c1imatic variations are stated for the Mediterranean and Atlantic littorals, with different tidal ranges and tectonic trends. Different stages can be envisaged in the coastal evolution of almost all the analyzed areas from the beginning of Holocene (10.000 BP): at ca. 7.000 BP (Flandrian maximum) with a change from open estuaries to aggradational processes (Cádiz Gulf subsiding area), basal peat (Valencia Gulf, subsiding area) and development of microcliffs (Mediterranean uplifting areas). From 7,000 to 2,700 BP a first progradation phase with development of spit bars took place in the mediterranean uplifting areas, whilst in the atlantic subsiding one starts the aggradation processes in the formerly open estuaries, an also from ca.4,OOO BP development of spit-bar system. A second progradation phase ofthe spit bars systems occurs between 2,400 and 500 BP both in Almería and Cádiz Gulf where a change from aggradation to progradation takes place in the estuary environments, and with a change in the direction of longshore drift (Mediterranean) and prevailing winds (both areas) at ca.2,400 BP. At ca. 1,200 BP a sudden paleogeographic change took place in estuary environments. From 500 BP up to nowa marked in crease of coastal progradation in all littorals is observed. Climatic interpretations led to correlate anticyclonic conditions (as it happened during Little Ice Ages) with the growing of spit bar systems and progradation, while low pressure conditions (as during Medieval Warm Period) coincides with no progradation. In the Canary Islands, the development of storm ridges at ca. 3,500 BP can be correlated with an intensification of trade winds.