الفهرس 
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Abstract
The present study deals with geological, geochemical and radioactivity
with mineralogical study of Um Rakhat El-Missikat area in the central Eastern
Desert of Egypt. Field investigations indicate that the exposed rock units are
represented by older granitoids (quartz diorite and tonalite) and younger
granitoids (monzogranite and syenogranite). Uranium mineralization of Um
Rakhat El-Missikat area is associated with red, black and jasperoid silica veins,
dissecting NE SW shear zone. Alterations are represented by greisenization,
silicification, hematitization, kaolinization and fluoritization.
Petrographically, quartz diorite and tonalite essentially composed of
plagioclases, hornblende, biotite, quartz and minor potash feldspars as essential
minerals while titanite, apatite, zircon and opaques are the accessory minerals.
Saussurite and chlorite are secondary alteration minerals. Granodiorite exhibits
hypidiomorphic and gneissose - like textures. It is mainly composed of
plagioclases, quartz, hornblende, biotite and potash feldspars. Opaques, apatite
and titanite are the accessory minerals whereas chlorite and sericite are the
secondary alteration minerals. Monzogranite is mainly composed of quartz,
potash-feldspars, plagioclase (oligoclase), subordinate biotite (partly
chloritized) and muscovite as essential minerals. Fluorite, zircon, apatite,
titanite, monazite, epidote, zoisite and opaques are accessory and secondary
minerals. Syenogranite is essentially composed of potash feldspar, quartz, sodic
plagioclase and biotite. Muscovite, zircon, apatite, monazite, allanite, fluorite
are accessory minerals.
Geochemical investigations indicate that the studied granitoids have calcalkaline
nature. Concerning the tectonic setting, the tonalite and granodiorite
indicate that they are assumed to be generated in volcanic arc granite (VAG)
environment while monzogranite and syenogranite plot within plate granite
environment (WPG). In general terms, the REEs patterns of the tonalite and
granodiorite are enriched in LREE relative to the HREE while the monzogranite
and syenogranite exhibit wing shape.
Radiometric studies indicate that some of the younger granitoids in the
study area are uraniferous granitoids whereas the altered granitoids along the
shear zone exhibits the most anomalies targets, as well as jasperoid silica.
Mineralogical investigation reveals the presence of radioactive minerals
(e.g., uranophane, thorite) and radio-element bearing minerals (e.g., monazite,
Allanite and zircon).
Remote sensing and GIS techniques have been applied using Sentinel-2A
images; ASTER images day and night Polsar, Sentinel-1 radar images, Digital
Elevation Model (DEM) data, geological and topographic maps of different
scales. Different types of image enhancements (filtering, decorrelation
stretching, spectral files, band ratio and principal component) have been applied
to produce images show clearly the exposed rock units with different color and
topographic expressions and discrimination between the various dykes in the
area. Radar Polars and ASTER images posse well structural lineaments (faults
and fractures features) and the morphology. The whole processing was carried
out using ENVI 5.2; ERDAS imagine 9.2, Gloppar mapper program and
ArcGIS software.
Near the entrance of the mine, radioactive measurements at some silica
veins show that there are four radioactive anomalies of high eU, eTh (ppm) and
K (%) values. These anomalies are found in some of the black silica veins
injected in the ENE shear zone of the studied area east and west the entrance of
the mine. The sites of radioactive anomalies are characterized by intersection of
NW and NNW faults within the ENE shear zone. The maximum value of eU is
685 and minimum185 ppm, with average 390 ppm while eTh ranges between
64 and 41 ppm, with average 51ppm and K% ranges between 4.3% and 1.4 %
with average 3.2 %.