Late Pleistocene relative sea level high stand deposits of Portuguese Estremadura
Presentation
Overview
Overview
Description
Evidence from the Estremadura coast of central Portugal shows widespread landscape instability coincident with Neanderthal occupation during Marine Isotope Stages 3-5 (MIS 3-5). Relative sea level high stands during this period are preserved in uplifted coastal sediments in various tectonic settings between Peniche and São Pedro de Muel, and are dated by luminescence (OSL) and radiocarbon methods to around 35, 41, 62, and 100 ka BP. Middle Paleolithic archaeological sites (Mira Nascente and Praia Rei Cortiço) are found within foredune or tidal flat sands in close lateral association with organic-rich estuarine and channel fill facies. The high stand deposits were locally reworked by fluvial and colluvial activity during the MIS 2 lowstand, and buried by an aeolian dune field that extends up to 15 km inland. OSL ages imply that the dunes were emplaced in some areas by the end of MIS 3 (~28 ka BP) and were intermittently active until the end of MIS 2 (~11 ka BP). The dunes have been re-activated by human disturbance since the Roman period (~2 ka BP). Thick alluvial fills in coastal-draining river valleys and estuaries suggest high rates of upland erosion associated with cold/arid phases of MIS 4, 3, and 2. Every one of nine OSL ages we have obtained on Pleistocene aeolian, fluvial and colluvial sections fall within the ±1σ error range of a cold episode between 10-70 ka BP, including Heinrich events, the Younger Dryas, or MIS 4. These findings highlight the magnitude of geomorphic response to climatic instability on the Portuguese margin during the last glacial stage and provide paleoenvironmental context for newly-discovered archaeological sites in the region.
