SURFACE AND SUBSURFACE STRUCTURAL FEATURES CONTROLLING URANIUM MINERALIZATION AT GRANITIC-HAMMAMAT CONTACT, WADI BELIEH, NORTHERN EASTERN DESERT, EGYPT

Abstract

Intensive exploration and radioactivity works carried out at Gabal Gattar area led to the discovery of some significant uranium mineralized occurrences along the extreme northern peripheries of Gabal Gattar granitic pluton The uranium mineralization at G-V occurrence, which is the essential aim of this work, it is mainly restricted to the contact zone between the younger granite of G. Gattar and the older Hammamat sedimentry rocks of G. Umm Tawat, to the north, along the southern bank of Wadi Belieh. G. Gattar area is located at the northern Eastern Desert of Egypt at about 35 km west of Hurghada city. The prospect area (G.V) is located north G.Gattar at the intersection of latitude 270 7' 30" N and longitude 33017' 5" E. Survey works was carried out using 1:10,000 topographic maps as a base over which all the mapped geological information was projected The main geological and structural features around the uranium mineralized occurrence were studied. The mapped area shows the presence of the following rock types starting with the oldest. Hammamat sedimentary rocks, medium grained biotite granites and dykes . Most of the structure features recorded in the studied area such as folds, faults and joints were carefully studied. Different faults and shear zones controlling U mineralizations were recorded especially those trending: N-S, NNE-SSW, NE-SW, E-W and ENE-WSW, NNW-SSE and NW-SE. GV U-occurrence is one of the most promising occurrences of G. Gattar prospect. It is located at the northern periphery of Gattar batholith along the southern bank of W. Beleih at the northeastern part of the mapped area. The U-mineralization is present at the reverse fault contact between Hammamat sedimentary rocks and younger granites. Several scattered xenoliths of the sediments are seen enclaved and carried by the granite. Many lenses of secondary uranium mineralization are present along the contact between the episyenitized granite bodies. Due to alterations and extensive alkali (K) metasomatic process which acted along the contact, the Hammamat sediments are bleached and highly altered. The present thesis is concerned to the study of both surface and subsurface geological features of GV uranium occurrence.A detailed surface geological and structural map on scale 1:200 m for G-V uranium occurrence was constructed. A planimetric map of scale 1:50 was constructed for G-V mining works which serve as a base for plotting geological, structural and radiometric data. Surface mineralized zone at GV occurrence is of vein shape with 64m long and 1.65m in thickness, its strike is N600 – 700E and dipping to SE with dip angle of 510 – 860 this surface mineralization extend to the subsurface at 60 ~ 66m at the entrance of the main adit, and also recorded at the western wall of the open pit. Mineralization also appears at the subsurface along fault contact at a distance 10m of the drift parallel to the main adit. The detailed subsurface studies of the mineralized faults and fractures were carried out in G-V mining works revealed the presence of a major subsurface uranium mineralized trend recorded in the main adit and the drift. It is essentially the ENE – WSW trend where the uranium mineralization occurs as thin films along the fractures of the episyenitized granite and its adjacent Hammamat sedimentary rocks. Detailed surface radiometric investigation in G-V uranium occurrence revealed that there are other six uranium mineralized zones, namely G-13, G-14, G-15, G-16, G-17and G-18 added to the previously explored occurrences in the study area