Sedimentological, modal analysis and geochemical studies of desert and coastal dunes, Altar Desert, NW Mexico
Por:
Kasper-Zubillaga J.J., Zolezzi-Ruíz H., Carranza-Edwards A., Girón-García P., Ortiz-Zamora G., Palma M.
Publicada:
1 ene 2007
Resumen:
Sedimentological, compositional and geochemical determinations were carried out on 54 desert and coastal dune sand samples to study the provenance of desert and coastal dunes of the Altar Desert, Sonora, Mexico. Grain size distributions of the desert dune sands are influenced by the Colorado River Delta sediment supply and wind selectiveness. The desert dune sands are derived mainly from the quartz-rich Colorado River Delta sediments and sedimentary lithics. The dune height does not exert a control over the grain size distributions of the desert dune sands. The quartz enrichment of the desert dune sands may be due to wind sorting, which concentrates more quartz grains, and to the aeolian activity, which has depleted the feldspar grains through subaerial collisions. The desert dune sands suffer from little chemical weathering and they are chemically homogeneous, with chemical alteration indices similar to those found in other deserts of the world. The desert sands have been more influenced by sedimentary and granitic sources. This is supported by the fact that Ba and Sr concentration values of the desert sands are within the range of the Ba and Sr concentration values of the Colorado River quartz-rich sediments. The Sr values are also linked to the presence of Ca-bearing minerals. The Zr values are linked to the sedimentary sources and heavy mineral content in the desert dunes. The Golfo de Santa Clara and Puerto Peñasco coastal dune sands are influenced by long shore drift, tidal and aeolian processes. Coarse grains are found on the flanks whereas fine grains are on the crest of the dunes. High tidal regimens, long shore drift and supply from Colorado Delta River sediments produce quartz-rich sands on the beach that are subsequently transported into the coastal dunes. Outcrops of Quaternary sedimentary rocks and granitic sources increase the sedimentary and plutonic lithic content of the coastal dune sands. The chemical index of alteration (CIA) values for the desert and coastal dune sands indicate that both dune types are chemically homogeneous. The trace element values for the coastal dune sands are similar to those found for the desert dune sands. However, an increase in Sr content in the coastal dune sands may be due to more CaCO3 of biogenic origin as compared to the desert dune san
Filiaciones:
Instituto de Ciencias del Mar y Limnología, UNAM, Mexico, D.F. 04510, Mexico
Facultad de Ingeniería, UNAM, Mexico, D.F., Mexico
Instituto de Geología, UNAM, México, D.F., Mexico
Instituto de Geofísica, UNAM, Mexico, D.F., Mexico
Laboratorio de Geoecología, Centro de Investigaciones en Ecosistemas, UNAM, Campus Morelia, Morelia, Mexico
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