Geophysical Exploration for Iron Ore Prospect using Gravity Method in Meru County, Kenya
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Date
2019-04
Authors
Nguru, Joseph Mugacia
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Ground gravity survey covering an area of 60km2 in Kimachia and Mbeu, area of Tigania-
West Sub-County of Meru County, Kenya was conducted to establish iron ore extent in the
area. A Sodin 410 gravimeter was used to measure the gravity field‟s variations in the 278
established stations. At each station the location coordinates and elevation were obtained
using Global Positioning System, Garmin 45 model. The time of measurement at each
station was also recorded. Gravity reductions and removal of regional trends was done.
Computer software Surfer 11 was used to plot Bouguer anomaly contour map. Qualitative
interpretation was used to discern positive Bouguer anomalies in the map. Five profiles
were drawn on discerned anomalies, one oriented in the SW-NE direction and the other
four in NW-SE direction. Half width and Gradient amplitude ratio methods together with
Euler de-convolution were used to image the sub-surface and to establish limiting depths of
anomalous bodies which were later used for start models. Modeling using Grav-2 dc
software was done in fitting models, which established bodies at depths ranging 0-200m
below surface. The anomaly map was also used in estimating the excess mass at
3.078109×10 13 kg. Chemical analysis of rock samples from selected stations mainly within
gravity highs was done to determine the percentages of major minerals, magnetite included.
The analysis indicated an average of 19.1 % of iron content. Gravity models indicated high
density bodies and chemical analysis confirms presence of iron ore.
Description
A Research Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Masters of Science in the School of Pure and Applied Sciences of Kenyatta University. April, 2019