GEOCHEMISTRY OF ACCESSORY MINERALS ASSOCIATED WITH RADIOACTIVE MINERALIZATION IN THE CENTRAL EASTERN DESERT, EGYPT

Prominent shear zones in the low Ca granitic plutons of El-Missikat an d El-Erediya, central Eastern Desert of Egypt trend northwest-southeas t, north-south and northeast-southwest. The shear zones are filled wit h jasper containing uraniferous mineralisation with accessory uranopha ne, pitchblende and uraninite, accompanied by pyrite, galena, magnetit e-titanomagnetite, ilmenite, hematite, rutile, titanite, fluorite, zir con, monazite, apatite and tourmaline. It is possible to discriminate between the mineralisation of the two prospects on the basis of the Pb and Cu content. The El-Missikat veins contain more Pb and less Cu, co mpared to those of El-Erediya. The mineralising hydrothermal fluid was ferruginous and highly enriched in many trace elements but was marked ly deficient in europium, The content of the high field strength eleme nts is mostly determined by the amount of zircon, monazite and rutile. Colouration in fluorite is associated with considerable enrichment in the REEs. (C) 1997 Elsevier Science Limited.