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| Format: | Artículo científico |
| Language: | en |
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Universitat de Barcelona
2005
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| Online Access: | https://www.redalyc.org/articulo.oa?id=50530102 |
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Table of Contents:
- Constraints on alluvial clay mineral assemblages in semiarid regions. The Souss Wadi Basin (Morocco, Northwestern Africa) A. Elmouden L. Bouchaou M. Snoussi Ciencias de la Tierra Erosion Souss Wadi Clay minerals Semiarid climate Illite, chlorite and kaolinite, resulting directly from substratum weathering, dominate the clay assemblagesrecorded in altered rocks and soils of the Souss Wadi watershed. Nevertheless, the transformation and neoformationof diverse clay minerals, which is mainly controlled by changing climatic, lithological and topographicconditions, enables one to establish three distinctive source areas. High altitude, largely watered zones wherechlorite is transformed into vermiculite; middle altitude drier areas where more pronounced seasonal contrastinduces the transformation of chlorite into chlorite-smectite mixed layer; finally, semiarid low altitude zoneswith gentle slopes where the weathering of carbonate-dominated substrata, evaporation and chemical concentrationresult in smectite and palygorskite neoformation. These minerals, which result from transformation andneoformation, provide suitable environmental indicators and local to zonal tracers of sediment contribution.Nevertheless, the original clay mineral assemblages undergo a significant homogenisation due to the destructionof most of the transformed and neoformed minerals during fluvial transport. As a consequence, inherited clayminerals (illite, chlorite and kaolinite) usually dominate the assemblages recorded in the downstream alluvialsediments. The clay assemblages recorded in different tributary wadi alluvial deposits reflect major sedimentcontribution from the High-Atlas and the older alluvial plain deposits affected by intensive erosion. On the otherside, Anti-Atlas contribution is lesser as a consequence of its wide tableland topography and the widespreadoutcropping of karstified carbonate rocks, which enhance water infiltration and preclude sediment supply. 2005 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50530102 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.1 Vol.3