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2 2025

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Mineral composition and aeolian evolution of dune deposits in Merzouga-Tafilalet, south-eastern Marocco

Harchane Smail, Azzouzi Nassareddine, El Hammichi Fatima, Tabyaoui Hassan, El Hammouch Naoual, Lahrach Abderrahim

Studia Quaternaria

2025

Vol. 42, Nr 1

27--40

Morocco, like many countries in arid zones, is faced with desertification, particularly in the south and southeast. Shifting dune sand is a key indicator of this phenomenon. The study of aeolian dynamics in the Merzouga-Tafilalet region aims to understand desertification processes, from rock erosion to sediment transport and deposition. A mineralogical and granulometric analysis of dune sand was carried out to determine their composition and origin. The study was based on petrographic examination and identification of the transport mechanisms involved. The sandy deposits are predominantly composed of quartz, with the presence of oxides, heavy minerals, feldspars, micas and calcite. These elements originate from the crystalline formations of the Anti-Atlas and are transported by aeolian and hydrological processes. Analysis of the quartz grains reveals different morphologies, reflecting the history of their transport and deposition. Aeolian dynamics have led to the formation of distinct granulometric fractions, each corresponding to a specific aeolian period. The mixing of these fractions results from the alternation of strong and weak wind regimes, as well as stabilization phases linked to wind degeneration. This study provides a better understanding of the evolution of dune sand in the face of environmental change.

Distribution of fire activity in Africa, criticism of previous explanations based on a data base from 2001 to 2021

Mourjane Mohammed, Tabyaoui Hassan, El Hammichi Fatima

Studia Quaternaria

2025

Vol. 42, Nr 1

75--80

Africa is the continent most exposed to fires, accounting for over half of the burned areas and pyrogenic greenhouse gas emissions globally. Fire seasonality in Africa follows the dry seasons, primarily from October to March for the Northern Hemisphere, with a peak in December–January, and from April to October for the Southern Hemisphere, with a peak in August. In 2001, we monitored active fires monthly, observing significant changes based on the seasons. The equatorial and southern regions of Africa showed a higher concentration of fires, less in the north. This variation has been consistent for 21 years, up to 2021. A strong correlation exists between the latitude of African regions and fire abundance. Equatorial countries experience more fires during the period between December and March, while southern countries see more during the other time of year period. Key factors include the accumulation of biomass, which fuels fires during the rainy season, and increasing human pressure, especially due to the need to warm up.