Scanning electron microscopy analysis of quartz grains in desert and coastal dune sands (Altar Desert, NW Mexico)

Abstract

A scanning electron microscopy analysis was performed for 570 quartz grains from desert and coastal dune sands in NW Mexico. Our main goal is to present a new application in the use of ternary diagrams with logistic normal confidence region boundaries of normalized data based on quartz surface textures (i.e., constrained data) of desert and coastal dune sands. This was done to demonstrate that quartz surface textures from desert and coastal dune sands are not significantly different even though there are apparent dominant processes (mechanical, chemical) that produce different surface textures in quartz grains from both dune types. This may be associated with the fact that quartz grains deposited in the dune sands do not reflect a second cycle of transport associated with an aeolian environment because of their low textural maturity, provenance, closeness to the source rock, and little attrition process. This study indicates that quartz grains from the desert dunes display mechanical textures probably associated with the Colorado River Delta and granitic sources that do not reflect accurately the aeolian mechanisms controlling the transport of these grains. Also, some quartz grains display chemical surface textures probably linked to the hydrothermal activity near the Colorado River Delta. In general, quartz grains display conspicuous surface textures. Quartz from coastal dune sands displays chemical surface textures that indicate quartz precipitation from silica-saturated water and, to a lesser extent, it displays mechanical features. These similarities might be associated with the mixing of processes (mechanical, chemical ) in quartz from the desert and coastal dune sands.

Roundness in quartz grains from inland and coastal dune sands, Altar Desert, Sonora, Mexico

“…5) that the SLRC indeed concentrates more quartz grains with less aeolian transport compared to the EP which has more rounded and abraded quartz grains. In both sites, quartz may be dominantly sourced from alluvial deposits from the Colorado River Delta by northwesterly and northerly winds as it was evidenced by previous SEM, petrographic and geochemical studies Kasper-Zubillaga and Faustinos Morales, 2007) (Fig. 9).…”

Mineralogy and grain morphology of the aeolian dune sand of Toshka area, southeastern Western Desert, Egypt

“…The probable source of Toshka sands was an old (late Pleistocene) dune sand mainly originated from the weathering of the Nubian sandstone since the mid-Tertiary by fluvial streams and lakes during earlier humid periods and by aeolian processes during arid periods (Hamdan et al, 2014). These interpretations are supported in the present study by the relative abundance of angular quartz than the rounded quartz grains in Toshka sands together with mechanical surface features explored by SEM analysis carried out for quartz grains such as conchoidal fractures and smooth surfaces, which are characteristic features for transportation processes of fluvial and aeolian environments, respectively (Krinsley and Margolis, 1969;Higgs, 1979;Kasper-Zubillaga and Faustinos Morales, 2007).…”

Microtextures on Quartz Grain Surfaces in the Beach Sediments of Southern Hodeidah, Red Sea Coast, Yemen

“…The microtextures of quartz sand grains can provide valuable information about the various processes acting on grains during transportation and after deposition [10,11]. Hence, the surface textural study of quartz grains is considered to reflect the sedimentary history of quartz: parent rock, transportation process, provenance, and depositional environment [9,[12][13][14][15]. The Tihama coastal plain, which stretches along Yemen's Red Sea coast and is around 500 km long and 30-60 km wide, occupies an area of about 10% of the total country area [16].…”