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,
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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.
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