A COMPOSITE GEOPHYSICAL INVESTIGATION OF BURUM DOLOMITIC MARBLE DEPOSIT, FEDERAL CAPITAI TERRITORY, NIGERIA
A COMPOSITE GEOPHYSICAL INVESTIGATION OF BURUM DOLOMITIC MARBLE DEPOSIT, FEDERAL CAPITAI TERRITORY, NIGERIA
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Date
1988-11
Authors
ANEKE, SYLVANUS CHUKWUMA
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Abstract
A composite geophysical investigation was carried out
on the Dolomite marble deposit at Burum. In the Federal Capital
Territory. The aim was to delineate the lateral extent of the
deposit, provide a preliminary estimate of its' quantity and to
identify the geotechnical and hydrogeological conditions of the
deposit. Ihe Electrical Resistivity Profiling, Vertical Electrical
Sounding and VLF (EM) Methods were employed for the investigation.
There is a close match and striking agreement between the
outlines of the marble deposit (fig. 4.1) as obtained from the
resistivity profiling (fig. 2.8) and VLF (EM) data (figs 2.11, 2.12
and 2.13). The figures show that the deposit extends laterally for
about 950m in the NNE - SSW direction with an average width of about
120m.
Based on geophysical (VES) and borehole data, the shape of
the deposit has been approximated to that of an inverted triangularprism
with a rectangular top model (fig. 4.2). It has a variable
central axial thickness with an average of about 61m. The minimum
ore reserve of the deposit was consequently calculated to be about
9.74 mi11ion tonnes.
The VES results indicate four geoelectric layers with
resistivities of 250 to 2000 Ohm - m for the firsl layer, 25 Lo 60
Ohm - m for the second layer, 65 to 96 Ohm - m for the third and
1950 to 4000 Ohm - m for the fourth layer. The Third layer is replaced
in some regions by a geoelectric unit with resistivity of 105 to 130
Ohm - m.
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The results show a thickness varying from 0.4 to 0.9 for the first
layer, 2 to 20m for the second layer, 10 to 46m for the third layer.
The other geoelectric unit which replaced the third layer in some
regions has a thickness varying between 39.5 and 102m, while the
fourth layer is of infinite thickness. These results are in
agreement with those deduced from borehole data from the area.
The first two geoelectric layers constitute the overburden
whose thickness varies between 0 and 25m within the project area.
The total volume of the overburden overlying the deposit is
estimated to be about 0.137 x 106 m3.The region bounding the
deposit to the north has comparatively lower apparent resistivity
values (18 - 60 Ohm - m) than the region bounding it to the south
(with apparent resistivity values of 100 to 400 Ohm - mV Using the
results of the investigations, comparatively weak zones have been
identified and some per-mining and hydro-geological conditions of
the deposit have been highlighted
Description
Thesis submitted to the Ahmadu Bello University
in partial fulfillment of the requirements for
the award of the degree of Master of Science in
Applied Geophysics.
Department of Physics
Faculty of Science
Ahmadu BPLLO University, Zaria
November, 1988
Keywords
COMPOSITE,, GEOPHYSICAL,, INVESTIGATION,, BURUM,, DOLOMITIC,, MARBLE,, DEPOSIT,, FEDERAL CAPITAI,, TERRITORY,, NIGERIA