Microtextural patterns as an archive of geomorphic and pedogenic response to anthropogenic humidification in an arid dune system (Morocco)

Abstract

Understanding the response of arid soil-landscape systems to changes in moisture regimes is critical for assessing their stability. This study investigates the Elfeija dune field in southeastern Morocco, a site chosen for its well-preserved record of both natural climatic cycles and recent anthropogenic impacts. The process-response dynamics were investigated using quartz grain exoscopy (SEM-EDS) as a primary indicator. The analysis reveals a polyphasic history where subsequent pedogenic processes overprint primary geomorphic signatures. The initial state of the parent material is defined by a dominant suite of aeolian microtextures, including high-gloss polish and mechanical impact marks, indicative of prolonged transport in a mobile dune system. This primary surface is consistently altered by features diagnostic of incipient pedogenesis, such as chemical dissolution etching and authigenic growth of complex iron- and chlorine-rich aluminosilicate precipitates. Significantly, the recent, widespread expansion of irrigated agriculture provides a powerful modern analogue for the natural arid-humid cycles of the Quaternary.The seasonal, human-induced humidification of the sandy substrate creates the precise conditions required for these chemical alteration processes. The study concludes that the Elfeija geosite serves not only as a high-fidelity archive of past climatic shifts but also as a real-time laboratory for studying the geomorphic and pedogenic response of an arid system to modern anthropogenic forcing.