Refinement of the environmental and chronological context of the archeological site El Harhoura 2 (Rabat, Morocco) using paleoclimatic simulations

Abstract

This study illustrates the strong potential of combiningpaleoenvironmental reconstructions and paleoclimatemodeling to refine the paleoenvironmental and chronologicalcontext of archeological and paleontological sites. Wefocus on the El Harhoura 2 cave (EH), an archeological sitelocated on the North Atlantic coast of Morocco that coversa period from the Late Pleistocene to the mid-Holocene. Inseveral stratigraphic layers, inconsistencies are observed betweenspecies presence and isotope-based inferences used toreconstruct paleoenvironmental conditions. The stratigraphyof EH also shows chronological inconsistencies in older layersbetween age estimated by optically stimulated luminescence(OSL) and a combination of uranium series and electronspin resonance methods (combined US–ESR). To inferglobal paleoclimate variation over the EH sequence in thearea, we produced an ensemble of atmosphere-only simulationsusing the LMDZOR6A model, using boundary conditionsand forcings from pre-existing climate simulations performedwith the IPSL Earth system climate model to matchthe different key periods. We conducted a consistency approachbetween paleoclimatic simulations and paleoenvironmentalinferences available from EH. Our main results showthat the climate sequence based on combined US–ESR agesis more consistent with paleoenvironmental inferences thanthe climate sequence based on OSL ages. We also evidencethat isotope-based inferences are more consistent with thepaleoclimate sequence than species-based inferences. Theseresults highlight the difference in scale between the informationprovided by each of these paleoenvironmental proxies.Our approach is transferable to other sites due to the increasingnumber of available paleoclimate simulations.