خصائص رمال الكثبان الهلالية في منخفض الخارجة (صحراء مصر الغربية)‎ : دراسة في الجيومورفولوجية التطبيقية

الملخص EN

analyses the statistical parameters of the sand grain size distribution Kharga Depression dunes applying the sieving technique and Folk and Ward's equation.

The results of the sieving analysis divulged that The sands of the study area dominated by mid-sized sand (∅ 1.35-2).

With coarse sand, medium and soft and very soft about 5% , 59.01% , 36% each respectively.

There is a strong correlation between the average size of sand classification factor values.

, Which means that all of our beloved size and patterns of classification depends on the nature of the original deposits.

The textural characteristics of the sand forming the dunes are unimodal with a modal class in fine sand size, moderately to very well sorted, positively skewed and mesokurtic.

Quartz grains are mainly subrounded to subangular.

Spherical values ranged between 91.1% 92.3% Northern region% total medium-sized sand grains (0.25-0.50 mm), While getting ball values in coarse sand grains (1-2 mm) ranging between 93.1% , 97.1.

, Due to the fact that aeolian sediments in study area derived from pleistocene alluvial sediments which covers the Northern study area, by winnowing And transferred to the inside through sandstorms, And then it has made a good distance from north to south region, So, the transportation over a distance ranging between 50 70 you led to the collision of particles to each other, and then taken spherical form.

It turns out the exact phenomena study on sand grain surfaces.

A study of the exact phenomena on the surfaces of sands grains Showed dominanc of mechanical demonstrations, It's th inverted dishes, And parallel longitudinal depressions and slick surfaces, v etched, cracks and joints.

While Phenomena caused by either chemical weathering in solvent cavities, Which means that weathering both played a major role in the formation of phenomena associated with desert environment.

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From the study heavy mineral characteristics, it is found that the sediments contains heavy minerals that consist of Rutile, Garnet, Sillimanite, Staurolite, Monazite, Zercon, Pyroxenes, Epidote, Amphiboles and Opaques minerals. heavy minerals study of economic importance.

It turns out heavy minerals are of economic value to each of them.