Pleistocene stratigraphy of aeolian deposits at the base of an energetic structural coastal slope: sedimentology and OSL chronology (Port des Canonge, Mallorca, Western Mediterranean)

Abstract

[eng] Aeolianite and colluvial deposits at coastal outcrops located at the base of an energetic and structurally complex coastal slope have been examined in northwestern Mallorca (Balearic Islands, Western Mediterranean). A chronological framework has been established using Optically Stimulated Luminescence (OSL) dating. Due to the intensive weathering and bioturbation of the aeolianites, OSL dates have been obtained from the fine-grained polyminerals found in the colluvial paleosoils interbedded between the aeolianite layers. This limitation does not stem from the scarcity of quartz, but rather from the fact that the available quartz grains have been reworked from underlying strata and are, therefore, not chronologically reliable. The outcrop reveals a complex interaction between aeolian and colluvial deposition, and both dating and facies analysis have identified four episodes of aeolian activity during Marine Isotope Stages 5 to2 (MIS5 to MIS2). The data suggest that aeolian transport and dune formation were particularly intense during global colder climatic intervals, coinciding with low sea levels, while colluvial deposits correspond to more humid conditions. Given that the outcrop architecture and its elevation relative to present sea level (i.e., the altitude at which it is situated in relation to the modern shoreline) are comparable to those of other outcrops in structurally stable areas of the island, it is inferred that the northwestern side of the Tramuntana Range has remained relatively stable since MIS 5.