Title of article :
Uranium-series disequilibrium dating of secondary uranium ore from the south Eastern Desert of Egypt
Author/Authors :
Yehia H. Dawood، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2001
Pages :
7
From page :
881
To page :
887
Abstract :
The secondary uranium ore of Um Ara mining area, south Eastern Desert of Egypt, is composed mainly of uranophane and β-uranophane. They occur in the oxidized zone as idiomorphic crystals filling cavities and as coatings on the fracture surfaces of the alkali-feldspar and albitized granites. The activity ratios 234U/238U and 230Th/234U of the secondary uranium ore and host rocks indicate that there were two main phases of uranium mobility in recent geological time. An earlier precipitation of uranium from solutions forming the secondary ore and a subsequent mobilization resulted in adsorption of uranium to the host granitic rocks. The 230Th/234U age of secondary uranium ore varies from (50±10) to (159+69/−45) ka whereas, the age of uranium adsorption to the rocks ranges from (18±6) to (38±5) ka. The time of secondary uranium ore precipitation can be attributed to the Saharan II pluvial period which prevailed in Egypt during humid oxygen isotope climatic stage 5. The later uranium mobility and subsequent adsorption by the rocks took place during Kubbaniyan and Nabtian pluvial periods that coincided with oxygen isotope stages 3 and 1, respectively.
Keywords :
Uranophane , Activity ratios 234U/238U and 230Th/234U , Uranium-series disequilibrium , Kubbaniyan pluvial period , Nabtian pluvial period , Saharan pluvial period
Journal title :
Applied Radiation and Isotopes
Serial Year :
2001
Journal title :
Applied Radiation and Isotopes
Record number :
541112
Link To Document :
بازگشت