Basem Ahmed Zoheir_Barramiya, OGR_2011.pdf

114 B. Zoheir, B. Lehmann / Ore Geology Reviews 39 (2011) 101–115
Fig. 11. (a) Rose diagram showing the major fault trends and related quartz veins at the Barramiya mine area, (b) Equal area stereogram (lower hemisphere) of fault planes great
circles and slip lineation, slickenlines along the vein walls, (c) Strain directions (principal orthogonal stresses σ1, σ2 and σ3) graphically determined according to the P and T dihedra
method of Angelier and Goguel (1979), and a paleostress tensor comparatively calculated using the inversion algorithm developed by Etchecopar et al. (1981), and interpretation of
the right-lateral shear system in relation to the mineralized and barren quartz veins, (d) Mohr diagram showing a distinct high differential stress regime during vein formation.
9. Concluding remarks
The geologic characteristics of the Barramiya deposit; its structural
control, host rocks, alteration mineralogy, mineralization style, timing
of the mineralization with respect to the deformation history, along
with the fluid and stable isotope data, are in accordance with the
orogenic mesothermal lode-gold deposit style in the sense of
Groves et al. (2003), analogous to other deposits in the Eastern
Desert (e.g., Helmy et al., 2004; Zoheir, 2008). The ore fluid
characteristics and estimated pressure–temperature conditions of
the Barramiya deposit are comparable to other orogenic gold deposits
elsewhere in the Eastern Desert (see El-Tokhi and El-Muslem, 2002;
Harraz, 2000, 2002; Zoheir, 2008), implying a regional system of
greenstone-hosted lode-type gold formations as an integral part of a
regional-scale event during the evolution of the Neoproterozoic
Arabian–Nubian Shield. However, interplay of a major right-lateral
shear system, concurrent(?) emplacement of granodiorite shoot and
attendant listvenitization of the ultramafic rocks define a unique
scenario of gold mineralization for the Barramiya gold deposit.
Acknowledgements
We appreciate the enthusiastic help of Dr. Robert Moritz (Univ.
Geneva) in the Laser Raman Spectroscopic measurements. Dr. A.
Cabral (Rhodes University, South Africa) and Dr. Adrian Boyce
(Scottish Universities Environmental Research Centre, UK) are
thanked for the laser ablation and stable sulfur isotope analysis.
Reviews by Dr. B. Tsikouras and an anonymous referee, and comments
by Prof. Nigel Cook substantially improved the manuscript and are
highly acknowledged.
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