Spectral signs of aeolian activity around a sand-dune belt in northern Algeria
Metadatos
Mostrar el registro completo del ítemAutor
Hassani, M; Saadoud, D.; Chabou, M. C.; Martín Peinado, Francisco José; Sánchez Marañón, ManuelEditorial
Elsevier
Materia
Dunes
Fecha
2019Referencia bibliográfica
Published version: Catena 182 (2019) 104175. https://doi.org/10.1016/j.catena.2019.104175
Resumen
Dune color has been used to investigate the provenance, stabilization, and age of the sand. Here, we look for
signs of aeolian activity in the colors of a sand-dune belt in northern Algeria. On the one hand, visible and nearinfrared
spectral analyses of satellite images and laboratory samples showed reddish, yellowish, and whitish
sands, depending on the amount of gypsum particles and Fe oxides coating quartz grains. Specifically, the
dithionite-extractable Fe content was related to a redness index calculated from remote-sensing data and the
abundance of hematite, estimated in the second derivative of the Kubelka-Munk function, paralleled the CIELAB
hue-angle of sand samples. On the other hand, a spatiotemporal analysis showed that the reddish sand had
undergone a continuous remobilization and dispersion throughout the area, reaching two large salt flats (sabkhas)
with seasonal water. Yellowish and whitish sands appeared as patches on the periphery of these sabkhas
and along the dune belt, exhibiting percussion marks and dissolution pits on the surface of quartz grains. Taken
together, the results suggest that the reddish sand partially loses its Fe-oxide coatings by mechanical abrasion in
the entrainment and reductive dissolution in the sabkhas during waterlogging, becoming yellowish. The periodic
reactivation by wind of reddish and yellowish grains, together with whitish gypsum particles formed by evaporation
as the sabkhas dry up, may explain the sorting of grains according to their mineralogy and size along
the sand-dune belt, resulting in striking color changes. Accordingly, color reflects sand movements and chemical
processes taking place in this dune system.