ALKALIC-METASOMATISM AND REDISTRIBUTION OF U, TH AND REE IN THE HYDROTHERMALLY ALTERED GRANITE OF GABAL ABU HARBA, NORTH EASTERN DESERT, EGYPT | ||||
Nuclear Sciences Scientific Journal | ||||
Article 2, Volume 2, Issue 1, 2013, Page 23-37 PDF (6.96 MB) | ||||
Document Type: Original Article | ||||
DOI: 10.21608/nssj.2013.30977 | ||||
View on SCiNiTO | ||||
Authors | ||||
ABDEL AZEEM A. RASHWAN1; MAHMOUD H. SHALABY2; MOHAMED E. ROZ2; MOHAMED A. WETAIT1; AMR A. ABDEL HAMID2 | ||||
1Depart. Geol., Fac. Sci., Benha Univ., P.O. 13518 Benha, Egypt | ||||
2Nuclear Materials Authority,Cairo, Egypt | ||||
Abstract | ||||
The late Pan-African granites of Gabal Abu Harba area occur in the North Eastern Desert of Egypt. Field and mineralogical studies indicate that the granites comprise coarse-grained biotite granite and mediumgrained leucogranite. The geochemical characteristics categorize these rocks as syenogranite and alkali feldspar granite according to the Ab-Or-An normative values. The syenogranite, as compared with the alkali feldspar granite, possesses lower A/CNK ratio values, higher P2O5, CaO, TiO2, Sr and Ba contents, and is depleted in Rb, Nb, Th, U. The U contents of the alkali feldspar granite (average=12.3ppm) suggest fertile-U source to constitute a suitable setting for uranium minerals formation by later hydrothermal fluids. The alkali feldspar granite was affected by hydrothermal solutions along its fault planes, causing a series of zones of wall-rock chloritization, sericitization, kaolinitization, carbonatization and hematitization as well as highly enrichment of U and slight mobilization for Th. The secondary uranium minerals, locally identified in these altered parts, comprise chiefly beta-uranophane and kasolite. Whole-rock geochemistry shows that the altered alkali feldspar granite experienced both sodic and potassic metasomatism. Mass balance calculations, with reference to unaffected alkali feldspar granite, evidenced loss for SiO2, TiO2, FeO, MgO, CaO and K2O and LREE contents, and gain of both the HREE (Tm, Yb and Lu) and most of the trace elements (Sr, U, Zn and Pb). | ||||
Statistics Article View: 148 PDF Download: 308 |
||||