RADIOACTIVE ACCESSORY MINERALS FROM STREAM SEDIMENTS AT WADI MAYET EL ABD, NORTHERN GATTAR AREA NORTH EASTERN DESERT, EGYPT.

Wadi Mayet El-Abd is located in the northern part of G. Gattar, north Eastern Desert of
Egypt. Significant remarks have been recorded on the heterogeneous distributions of heavy minerals
content along the stream course, where they are most common in both deeper sediments
and downstream sites. Moreover, these sediments appear to be slightly favorable delivery pools
for thorium but not for uranium which is probably due to either the marked enrichment in the
thorium-bearing minerals or the selective leaching for uranium during the supergene processes.
The greater eU/U and eTh/U ratios, besides the negative values of the calculated authigenic
uranium and further the markedly reverse relationships between uranium and thorium as well
as uranium and Th/U ratio reveal the disequilibrium state of uranium and confirm U leaching.
The available data propose that, the study sediments are potential sink for radioactive accessory
minerals as well as rare metal minerals that may control the geochemical enrichment of trace
elements as; U, Th, Zr, Y, Nb, REE, Ba, Zn and V. The present work adopts the ESEM/EDXBSE
as an appropriate tool for the recognition of the accessory minerals. The minerals; betafite,
ishikawaite, xenotime, fluorite and zircon have been identified as the most abundant uraniferous
accessory minerals; whereas monazite dominates as thorium-bearing mineral. Moreover, thorite
and uranothorite have occasionally been recognized. A particular attention has been given to the
contents of the rare metals in general and radionuclides in paticular in the accessory minerals,
despite of their frequency in the whole stream sediments. In conclusion, the study sediments are
conceivably genetically related to common sources. Actually it reflects the mineral constituent
of the different rocks composing the drained area. Hence it may represent an erosional remnant
either of the bordering granites and Hammamat molasses terrenes of Wadi Mayet El- Abd or
drained from the further reaches which represent by the nearby weathered sediments of Wadi
Belih at downstream sites.