الفهرس 
Field geologyOnly 14 pages are availabe for public view
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Abstract
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ABSTRACT
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The present study concerned with the mineralogical, geochemical
prospection and radioelements distribution in Hamrat AI Jirjab stream
sediments, Esh EI Melaha range, north Eastern Desert, Egypt.
The area has been studied geologically, petrographically, stream
sediments distribution, minerlogically, chemically and radioactivity.
Harnrat AI Jirjab area is located in the northern part of Esh El Melaha
range, North Eastern Desert, Egypt. The area is delineated by Latitudes,
27°44’ 00”- 27° 48’ 00” N, and Longitudes, 33° IT 00” - 33° 22’ 30” E. It covers
an area of about 50 Km2, mainly occupied by Dokhan volcanics and alkali
feldspar granites with some dyke swarms of various composition as well as
stream sediments.
Wadi Abu Masannah is the main wadi passes through the area running in
a NW-SE direction and divided the study area into two main parts. This wadi is
filled with rock debris derived from the basement country rocks.
The area has been subjected to several successive tectonic events, which
affected all the exposed rocks. These tectonic events gave rise to many structural
features, mainly represented by joints and faults. The NW-SE, WNW-ESE and
E-W trends represent the significant joint sets in a decreasing order. On the other
hand, the NW-8E and N-S directions are the predominant fault trends. The field
cross-cut relation among faults shows a relative younger age for the N-S fault
trend, Salman et, al., 1995.
The ~ volcanics in the study area belong to mature Island Arc to
active Continestal Margin, and range in composition from andesite to dacite and
their pyroclastics.
The study younger granites are classified as alkali feldspar granites.
They are considered as I-type and originated from peraluminous calc-alkaline
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highly fractionated magma. They are considered as post-orogenic and formed
under an extensional regime suggesting crystallization during relaxation stage
that following collision. They are intruded in a crust of thickness> 30 Km at
water vapour pressure <2 kb, and crystallized at temperature < 8000 C.
Dykes of varying composition; acidic, intermediate and basic cut the
previously mentioned rock types and represent the post tectonic rock variety
among the Neoproterozoic Pan-African basement rocks of the Eastern Desert of
Egypt.
Sediments of the main wadi, Wadi Abu Masannah and its tributaries in
Hamrat AI Jirjab area exhibit mixture of detritus COmponents, represented by
pebble, granules, Sand and sizes less than very coarse silt « 0.063mm). Grain
size analyses revealed that the concerned sediments may have been derived from
dually and proximal sources due to it attain bimodality and very poorly sorting
characters, beside it display fine skewed, and wide range of kurtosis nature. The
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fluviatile environment is the most common provenance of the studied sediments.
The distribution of the heavy fractions in the sand size along the main wadi and
its tributaries show irregular trend that may attribute to different prevailing
conditions.
Sediments of Hamrat AI Jirjab area are considered as the natural trap for
the surrounding country rocks, alkali feldspar granites and Dokhan volcanics.
Moreover, they act as reservoir for the accessory and some radioactive minerals.
Uranium and thorium content is mainly concentrated in the sediments of
the northern part of Gabal Hamrat AI JiJjab alkali feldspar granites and in the
sediments of down stream of the main wadi.
Finally, thorite, uranothorite, monazite, zircon, fluorite, and allanite are
found to be the high radioactive minerals in addition to opaques which play
an important role in capturing uraniwn from circulating solutions.
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