Mineralogy and geochemistry of fine-grained Dahab stream sediments,Southeastern Sinai,Egypt:emphasis

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Mineralogical and geochemical characteristics of stream sediments collected from 30 stations in the Dahab-Wadi Kid area (southeastern Sinai,Egypt) are presented.The studied sediments contain considerable amounts of heavy minerals,including abundant Fe-Ti oxides,with up to 25.94% index figure that measures the relative abundance of heavy minerals to light minerals.Immaturity of the sediments and nature of Fe-Ti oxide intergrowths,in addition to some non-opaque heavy min-erals,indicate multiple provenances with contributions from a variety of Neoproterozoic mafic to felsic intrusions.Appreciable amounts of heavy minerals are derived from schists that belong to the so-called Wadi Kid volcano-sedimentary group.Owing to the considerable contribution of the felsic intrusions represented by within-plate granites,the sediments are enriched in REE-bearing minerals (e.g.,monazite,cerianite,La-cerianite and allanite),V-bearing thorite,zircon,and a ZrO2 phase.The majority of Fe-Ti oxides are derived from the mafic intrusions,and they show evidence of pre-,syn-and post-depositional phases of alteration and formation of intergrowths.As to the geo-chemical signature of the bulk silt fraction,there is remarkable enrichment of LREEs with distinct negative Eu anomaly,and this supports dominance of a provenance dominated by felsic intrusions (i.e.,the A-type within-plate granite and associated pegmatites).Also,the felsic prove-nance is responsible for slight abnormality of ΣU + Th content (up to ~ 37 ppm) and few anomalous samples bear uraniferous zircon and Ce-type monazite.The present paper sheds light on the fertility of the Dahab stream sediments in some economic minerals for possible future exploitation,not for gold only,but for potential REE-bearing minerals that are needed for a wide spectrum of modern technological industries.
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