A GEOLOGICAL-GEOCHEMICAL-GEOPHYSICAL INTEGRATED STUDY ON UMM NAR IRON ORE FROM THE CENTRAL EASTERN DESERT OF EGYPT

Document Type : Original Article

Authors

1 (1) National Research Institute of Astronomy and Geophysics, Helwan, Cairo, Egypt.

2 (2) Geology Department, Faculty of Science, Tanta Univ., Tanta, Egypt.

3 (3) Geology Department, Faculty of Science, Menofia Univ., Sheeben Elkoom, Egypt.

Abstract

Banded Iron Formations (BIFs) have economic interest as they host the world’s largest iron ore and
much gold deposits. Umm Nar BIF is one of the oldest and biggest arc sedimentary rock units in the Precambrian
sequence of the Eastern Desert of Egypt that strongly influenced by the deformation processes during or after the
closure of the Mozambique Ocean (650-620 Ma). The result was multi-deformational phases of faults and folding. This
study includes integrated geochemical and geophysical exploration methods. Detailed gravity and magnetic surveys
were carried out in Umm Nar BIFs. Gravity method is suitable for detecting iron ores due to contrast density in
compared to the schist country rocks. On the other hand, magnetic method is suitable for locating buried magnetite ore
bodies. The detailed geological and geochemical studies were also carried out. Several reductions then filtering were
done for both gravity and magnetic data. Obtained residual gravity and total intensity magnetic maps showed presence
of high anomaly areas which are identical and compatible with the surface beds bearing the BIFs which reflects that
the surface is extending subsurface mainly in the Northern Eastern part. The south-west high anomaly is compatible
with the gabbroic pluton that invaded Umm Nar fold. Depth of the source body was estimated up to 350 meter using
(Tikhonov et al., 1968) to regularize downward continuation to effectively help estimate the depths to the researched
near surface gravity and magnetic sources. Geochemical analysis for collected surface samples showed high
concentration of iron reaching up to 50-75% in the same areas of high gravity and magnetic anomaly.

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