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Corresponding Author

Othman, Ibrahim

Document Type

Original Article

Subject Areas

Earth science

Keywords

textural parameters; X-Ray Diffraction; Clay minerals; Petrography; radiometric

Abstract

This article includes geological, sedimentological and radiometric studies on some localities of new Administrative Capital. The subsurface soil of the study area composed fundamentally of weathered doleritic basaltic rocks and gravely sand. The sedimentological study includes particle size distribution, X-ray diffraction (X R D) for detection of clay minerals and petrographical studies, to describe and evaluate the textural parameters and statistical measurements to recognize the depositional pattern of sediment samples in the study area. The textural parameters results are graphic mean size varying from (-1.499f) to (5.195f) where the average is (1.205f) indicating medium sand grained. The sorting (σI) ranges from (0.307f) to (3.255f) with an average (2.297f) falling in very poorly sorted. The skewness (SkI) ranges from (-0.323f) to (0.838f) with an average of (0.361f) reflecting strongly fine-skewed. The kurtosis (KG) oscillates from (0.699f) to (4.348f) with an average (1.26f) proving Leptokurtic. Through the study of different relations between the grain size parameters, it was clear that deposition environment of the study area sediment samples is a river environment. The identification of the clay minerals using X-ray diffraction analysis involved that the clay minerals are montmorillonite and kaolinite. Petrographically, the studied samples clear that the basaltic rocks are classified as doleritic olivine basalts and the non-carbonate microfacies are classified as quartz arenite type. Siliceous and calcareous cement is commonly cement in sandstone samples. The results of radiometric examining confirm that the soil is unharmed to human activities where all radionuclides concentration 232Th, 238U, 226Ra, 40K and radium equivalent (Raeq) ranged from 1.24 to 13.59; 8.12 to 20.3; 22.2 to 55.5; 71.99 to 369.34, from 47.09 to 108.87 with average values 7.09, 15.41, 39.56, 249.12, 80.78 Bqkg-1 respectively and lower than (370 Bq/kg), external hazard index (Hex) range from 0.13 to 0.29 Bqkg-1 with an average 0.218 which is lower than ( 1 Bq/kg) and effective dose rate (Deff) range from 26.78 to 62.94 with a mean average value 46.79 μSvyr-1 as far below ( 70 μSv y-1 ) all radioactive measurements are lower than recommendable by (IAEA).

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