A DETAILED GRAVITY INVESTIGATION IN THE MALUMFASHI AREA OF KADUNA STATE, NIGERIA.
A DETAILED GRAVITY INVESTIGATION IN THE MALUMFASHI AREA OF KADUNA STATE, NIGERIA.
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Date
1984-10
Authors
CANDU, ASSABE HAUWA
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Abstract
Gravity measurements in the Malumfashi Area show that
the area is characterized by large negative Bouguer anomalies
ranging in values from -33 mGal to -65 mGal. Free-air
anomalies are distributed about a mean of +15 mGal and
projected sea level gravity value in the area is -41 mGal.
A regional anomaly ranging in value from about -56 mGal
in the south western part to about -44 mGal in the north
eastern part of the area is correlated to a gradual
thinning of the crust from southwest to northeast.
Negative residual anomalies in the area correlate well
with granite bodies thus confirming the acidic (low
density) nature of the older granites. Positive residual
anomalies of values up to about 12 mGal are correlated to
the schist bodies in the area.
From two dimensional modelling, it is estimated that
the schists in the area vary in depth from 3 km to 5 km
and the granite bodies have thicknesses of the order of
4 km.
High gravity gradients of up to 6 mGal/km at some
contact areas are attributed to sharp contacts and magmatic
stoping is thought to be the most likely mode of emplcement
of the granites. The sharp contacts also indicate
that the contacts are possibly faulted.
The positive Bouguer anomalies over the schists in
the area have a maximum amplitude of only -34 mGal. These
values are thought to be too low to indicate the existence
of more mafic rocks at depth. The schists in the
Malumfashi Area are therefore thought to have evolved
in an ensialic environment,
Description
Thesis submitted to the Ahmadu Bello University,in
partial fulfilment for the award of the degree of
MASTER OF SCIENCE IN APPLIED GEOPHYSICS
Department of Physics,
Faculty of Science,
Ahmadu Bello University,
Zaria - Nigeria
Keywords
GRAVITY,, INVESTIGATION,, MALUMFASHI,, KADUNA STATE, NIGERIA.