الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Banded Iron Formations (BIFs) are of economic potential, as they host the world’s largest iron ore and much gold deposits. The Umm Nar BIF is one
of the biggest arc sedimentary rock units in the Precambrian sequence of the
Eastern Desert of Egypt. It was strongly influenced by multi-deformation of
folding and faulting during or after the closure of the Mozambique Ocean (650-
620 Ma). The present study includes integration of data from geochemical and
geophysical exploration. Detailed gravity and magnetic surveys were carried out
in the Umm Nar BIFs using CG5 gravimeter and Overhauser magnetometer,
respectively. Gravity exploration was suitable for detecting the Umm Nar iron
ore due to its high density contrast with the schist country rocks. The magnetic
method was suitable also for locating buried magnetite ore body because of its
high magnetic susceptibility. In addition, gravity and magnetic surveys are
considered to be accurate, less-expensive, non-destructive environmentally
exploring tools, and have a wide coverage.
Geosoft Oasis Montaj 7.1 program, Sufer10 program, and Matlab codes
were used for processing, adjusting and interpreting both gravity and magnetic
data. The gravity data were corrected for the common gravity corrections (drift,
topography, free air and Bouguer). The magnetic data, on the other hand, were
corrected for the diurnal variations and reduced to the Northern magnetic pole.
Qualitatively, both residual gravity anomaly and magnetic to pole maps refer to
two main sets of faults directed NE-SW and E-W. Both maps identify high
anomaly areas matching the exposed iron bands reflecting their subsurface SW
extension. Depth of the source body was estimated to 100 - 400 meter using
Euler deconvolution method, and up to 350 meter using Downward
continuation. Combination of the two analyzed interpretation methods
(Tikhonov (1968) regularized downward continuation and Derivative Euler
Deconvolution) could effectively help in the estimation of the depths to the
centres of researched near surface gravity and magnetic sources.
Abstract
Furthermore, geochemical analyses of 20 positioned surface samples
were performed using X-Ray Fluorescence (XRF). These analyses showed high
concentration of iron reaching to 75% in the area of high gravity and magnetic
anomaly. Iso-chemical maps of the fluid mobile elements demonstrate well
matching with the Ag concentration, concluding the role of the metamorphic
fluids in ore shaping potential. The Pearson linear correlation matrices divide
chemical elements into six associations: i) Fe, Co, Ni, Ag, Nb, Sb, I, Ce, W, As,
ii) Si, iii) Na, Al, Mg, P, K, Rb, Y, Ba, Ti, Zr , iv) Mn, Cu, Mo, V, Sr, Br ± Pb,
v) Ca, Sc, vi) Cr, Se. Geochemical mapping constrains structural control of
metals with NW-SE and WNW-ESE faulting.