TITLE:
Origins of the Ruiniform Character of the Sandstones of the upper Member of the Dindefelo Formation, Madina Kouta Basin (Kédougou, Senegal, West Africa)
AUTHORS:
Cheikh Ibrahima Youm, Adama Gueye, El Hadji Sow
KEYWORDS:
Petrography, Sedimentary Figures, Fracturing, Ruiniform Landscape, Landslides
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.2,
February
13,
2026
ABSTRACT: The Dindefelo Formation, from the Madina Kouta basin in Senegal, is dated to the Tonian (1000 - 750 Ma). It comprises three members: silty clays, associated with fine quartz sandstones and intraformational conglomerates (DF1); clayey sandstone banks with clay-silty interbancs (DF2) and plurimetric banks, separated by clay-sandstone flats called ruiniform sandstones (DF3). Based on careful observations of sedimentary figures and petrographic analyses, here we examine the main processes that are at the origin of the ruiniform appearance of DF3. Of the three members of the Dindefelo Formation, DF3 has the highest mineralogical and petrographic maturity, and the highest density of sedimentary and tectonic structures. Forms present, include symmetrical, asymmetric, linguoid, interference ripples, dunes, bars, and anti-dunes. Tidal structures, desiccation cracks, hardened surfaces, bioturbations, and microbial mats are very abundant. This Formation is also characterized by a dense network of NNW-SSE, NE-SW and ENE-WSW oriented discontinuities that are more apparent on DF3 due to its characteristics. Under the combined action of these different synsedimentary and post-sedimentary processes, the sandstones are cut into plates, slabs, and parallelepiped blocks, giving rise to a ruiniform landscape in the form of giant teeth and mass landslides caused by a strong instability of the flanks. The originality of this model lies in the role played by sedimentary and tectonic structures.