A Gravity Survey Of the Older Granite Plutons In Katabu Area of Kaduna State
A Gravity Survey Of the Older Granite Plutons In Katabu Area of Kaduna State
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Date
1994-04
Authors
ANASIUDU, EMEKA FIDELIS
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Abstract
A gravity survey of the Precambrian Older Granite intrusions in Katabu area of
Kaduna state, northern Nigeria has been carried out to determine the structure and
probable mode of emplacement of the suite. A total of 153 stations were established at
intervals of one to two kilometers using a LaCoste and Romberg gravity meter for
relative gravity measurements and two altimeters for elavation determinations.
Laboratory measurements were carried out on 81 rock samples collected from the area.
Interpretation of the Bouguer anomaly field shows that the area is characterized
by prominent residual anomalies of -8 to +6mGal amplitude relative to a N-S trending
regional anomaly with an E-W gradient of the order of 0.4 mGal/km. Negative residual
anomalies correlate well with granite bodies while positive anomalies are associated with
quartz diorites and schists in the area. Two-dimensional modelling of the residual
anomalies reveals that the thicknesses of the quartz diorites and granite bodies vary from
2 to 5km and 2 to 7km respectively. It is estimated that the schists in the area have
thicknesses of the order of 1 km. The general configuration of the modelled bodies and
the pattern of the gravity anomalies suggest that the Older Granites make sharp contact
with the country rocks and were magmatically emplaced into the Basement Complex.
The Bouguer anomalies observed over the schists have a maximum of only -52mGal.
These values are considered too low to allow for the existence of more mafic rocks at
depth and the schists in Katabu area are therefore believed to have evolved in an ensialic
environment.
Description
A THESIS SUBMITTED TO THE POST GRADUATE
SCHOOL AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILMENT OF THE
REQUIREMENTS FOR THE DEGREE OF MASTER
OF SCIENCE, APPLIED GEOPHYSICS
DEPARTMENT OF PHYSICS
FACULTY OF SCIENCE
AHMADU BELLO UNIVERSITY
ZARIA, NIGERIA.
Keywords
Gravity,, Survey,, Older,, Granite,, Plutons,, Katabu, KADUNA STATE,