Environmental implications of electron microscope study of quartz grains’ surface textures on khors sediments, Lake Nasser, Egypt

Abstract

The present work aims to introduce the findings of the investigations of the surface textures of the quartz sand grains and their contribution to the history of sedimentation and diagenesis processes of the studied northern, middle and southern khors sediments in Lake Nasser. The surface textures observed in the quartz grains of the studied sediments emphasize both mechanical (i.e., upturned plates, meandering ridges, mechanical V-shaped pits, conchoidal fractures and oriented cleavage like plates) and chemical (i.e., silica precipitation and dissolution) features. The precipitation and dissolution phenomena are represented by silica globules, silica overgrowths, dissolved upturned plates, and diatoms plastered on sand grains. Such features imply a history of sedimentation of the khors sediments in Lake Nasser including deposition by aeolian processes, then fluvial sedimentation. The effect of consequent diagenetic processes in the khors sediments is represented by silica precipitation and dissolution features. The quartz surface texture reflects implications of the original aeolian environment of some grains in spite of the diagenesis effect.