Ground magnetic survey for the investigation of magnetic minerals at Iboro Village, Abeokuta, south-western Nigeria

2021 ◽  
Vol 20 (2) ◽  
pp. 99-106
Author(s):  
O.I. Popoola ◽  
O.A. Adenuga ◽  
E.O. Joshua
Keyword(s):  
Magnetic Anomalies ◽  
Geological Structure ◽  
Magnetic Survey ◽  
Magnetic Minerals ◽  
Contour Maps ◽  
Ogun State ◽  
Geological Map ◽  
Regional Gradient ◽  
Ground Magnetic ◽  
Iron Ore Deposit

The geological map of the old western region of Nigeria indicates the presence of iron ore deposit at Iboro village Ogun state (7.9983o - 7.99933o N, 3.5790o - 3.5890o E). Hence a ground magnetic survey was carried out at a location at Iboro village so as to delineate the subsurface magnetic anomalies and to know whether the anomalies favour accumulation of magnetic minerals. The survey was carried out using high resolution proton precession magnetometer model G-856X. Eight traverses were run at 5m separations and earth magnetic intensity values were measured at 10m intervals along each traverse; the acquired data were corrected for drift. The residual anomalies obtained by removal of regional gradient from observed data using trend analysis were presented as profiles and maps. The treated data were qualitatively and quantitatively interpreted and the results gave values for the total ground magnetic anomalies that varied between a minimum and maximum peak values of about -33.0 and 30.6nT respectively. Depth to the basement rock was estimated using Peter’s half slope method which gave a maximum depth of about 13m. The contour maps and the total relative graphs present the subsurface picture of the geological structure that is assumed to harbour the metallic minerals through the action of the field towards the concentration of anomalies. It was suspected that the overburden was relatively thin in the study area and the minerals were at a shallow depth.

Analysis of the Czech magnetic anomaly data obtained by ground-based and airborne magnetic surveys

2020 ◽  
Author(s):  
Pavel Hejda ◽  
Dana Čápová ◽  
Eva Hudečková ◽  
Vladimír Kolejka
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Data File ◽  
Ore Deposits ◽  
Substantial Contribution ◽  
Magnetic Survey ◽  
Contour Maps ◽  
Anomaly Map ◽  
Ground Magnetic ◽  
Airborne Survey

<p>The modern epoch of ground magnetic surveying activity on the Czech territory was started by the Institute of Geophysics by setting up a fundamental network of the 1<sup>st</sup> order in 1957-58. It consists of 199 points and was reoccupied in 1976-78 and 1994-96. The anomaly maps were constructed by subtraction of the IGRF model.</p><p>Extensive aeromagnetic measurements have been performed from 1959 to 1972 by permalloy probe of Soviet provenience. The accuracy of the instrumentation was about (and often above) 10 nT. The second period of airborne survey started in 1976. Thanks to the deployment of proton precession magnetometer, the accuracy improved to ~ 2 nT. Since 2004 the measurements were carried out by caesium magnetometer. The data were digitized, known anthropogenic anomalies were cleared away and data were transformed to the regular grid with step 250 m. The final data file of magnetic anomalies ΔT, administered by the Czech Geological Survey, represents a substantial contribution to the exploration of ore deposits and to the structure geology in general.</p><p>In view of the fact that data file of magnetic anomalies was compiled from data acquired by heterogeneous methods in the course of more than 50 years, our recent study is aimed at looking into the homogeneity of the data by comparison them with ground-based magnetic survey. A simple comparison of the contour maps showed good similarity of the large regional anomalies. For more detailed analysis, the variation of ΔT in the neighbourhood of all points of the fundamental network was inspected and the basic statistic characteristics were computed. Summary results as well as several examples will be presented accordingly as the INSPIRE compliant services and eventually as the user-friendly web map application and made available on the CGS Portal http://mapy.geology.cz/ and on the updated web of the CzechGeo/EPOS consortium www.czechgeo.cz. Incorporating the map into the World Digital Magnetic Anomaly Map (WDMAM – IAGA) is also under consideration. This data will also be interesting for the EPOS.</p>

Ground Magnetic Survey for The Investigation of Mineral Deposit at Itesi Village in Orile Ilugun, Odeda , South West Nigeria

2013 ◽  
Vol 2 (2) ◽  
pp. 110-117
Author(s):  
Sedara S. O ◽  
Joshua E. O ◽  
Popoola O.I
Keyword(s):  
Data Interpretation ◽  
Mineral Deposit ◽  
Magnetic Survey ◽  
Basement Rock ◽  
Contour Maps ◽  
Ogun State ◽  
Line Spacing ◽  
Positive Peak ◽  
Ground Magnetic ◽  
Peak Value

Advances in technique development and data interpretation have greatly improved our ability to visualize the subsurface. A Magnetic survey was carried out at a site in Itesi village, Ilugun, Odeda Local Government Area of Ogun State, Nigeria using a portable proton precession magnetometer (G-856 AX). A total of ten profiles were established in an E-W direction in the study area. The acquired magnetic field data were corrected for drift. Qualitative and quantitative interpretations were adopted to obtain negative peak value and the maximum positive peak value. The depth to top of basement rock was estimated using Peter’s Half slope. Likewise the depth to centre of basement rock was estimated using the Half width rule. The contour maps, 3-D surface map and the 1-grid vector map present the subsurface image. The whole survey area has a total length of 100 m at a line spacing of 10 m and a breadth of 45 m at 5 m spacing. The whole area was characterized by complete varying negative amplitudes from a very low peak value of about -9.9 nT and a maximum positive peak value of about 17.4 nT respectively. The closely spaced, linear sub-parallel orientations of contours from the South western part of the map suggest the possibility of faults or local fractured zones.

Resolving Optimum Magnetic Signatures for Drill-Hole Targeting in Gold Exploration – A Case Study for Mbudzane in Gwanda, Zimbabwe

2013 ◽  
Vol 3 (1) ◽  
pp. 9-29
Author(s):  
Dumisani John Hlatywayo ◽  
Emmanuel Sakala
Keyword(s):  
Drill Hole ◽  
Magnetic Survey ◽  
Gold Exploration ◽  
Rock Formations ◽  
Induced Polarisation ◽  
Line Spacing ◽  
Magnetic Signatures ◽  
Ground Magnetic ◽  
Tilt Derivative ◽  
Resistivity Image

Optimum magnetic signatures for drill-hole targeting in gold exploration in Mbudzane were resolved from induced polarisation-resistivity and magnetic anomalies. Total magnetic field and a gold-in-soil map showed the area is magnetically quiet with high anomalous values along old gold workings. Induced polarisation was carried out along a grid for lines of 500m length, 50m separation and a baseline oriented at 330˚. The survey comprised a gradient array and three real sections. The magnetic survey was conducted over the same grid as the induced polarisation. Stations were set at 5m intervals for a line spacing of 50m. The results show intense anomalies that suggest different degrees of magnetic alteration and a set of conjugate lineaments and faults that possibly control the mineralisation in Mbudzane. The tilt derivative of the reduced-to-pole image resolves the separation between anomalies, giving information on the faulting. High chargeability is confined to the sheared and silicified mafic schist. The gradient resistivity image revealed contact between rock formations. Real section IP shows coincident low chargeability – low resistivity anomalies close to the surface. Chargeability intensity increases with depth, suggesting incipient development of disseminated sulphide replacement zones. A strong correlation between ground magnetic inferred contacts and apparent resistivity-chargeability anomalies forms the basis for suggesting a new drill-hole targeting. They dictate both the depth and angle at which drilling should be carried out. These results should be applicable to any region where drill-hole targeting in gold exploration may be required.

The Use of Euler Deconvolution Technique in the Estimation of Depth to Magnetic Source Bodies around the Schist Belt Parts of Kano State, Nigeria

2021 ◽  
Vol 14 (1) ◽  
pp. 19-23
Keyword(s):  
Depth Estimation ◽  
Magnetic Survey ◽  
Schist Belt ◽  
Euler Deconvolution ◽  
Depth Estimate ◽  
Paper Detail ◽  
Magnetic Source ◽  
Deconvolution Technique ◽  
Proton Precession Magnetometer ◽  
Ground Magnetic

Abstract: Depth estimation of magnetic source bodies in parts of the Schist Belt of Kano, using Euler Deconvolution is presented in this paper. Detail ground magnetic survey was carried out using SCINTREX proton precession magnetometer to produce the Total Magnetic Intensity (TMI) map and consequently the residual map. The TMI ranges from 34,261 nT to 34,365 nT, while the residual field ranges from -160 nT to 115 nT. The depth estimate for contacts ranges from 6.5 m to 39.8 m, while that of dyke ranges from 8.9 m to 51.3 m. The depth estimation presented in this work is compared with the results of aeromagnetic study carried out in the same area and found to agree fairly well. Further, this also ensures the validity of aeromagnetic investigation in such applications. Keywords: Contacts, Dykes, Euler Deconvolution, Schist Belt. PACS: 91.25.F and 91.25.Rt.

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