Regional Interpretation Of The Airborne Magnetic Data From Northern And Central Namibia

Regional compilations of airborne magnetic data are becoming more common as national databases grow. Grids of the magnetic survey data are joined together to form geological province‐scale or even continental‐scale compilations. The advantage of these compilations is that large tectonic features and geological provinces can be better mapped and interpreted. We take a holistic approach to the joining of survey grids. The leveling of the grids into a regional compilation is treated as a single inverse problem. We use the weighted least‐squares method to find the best adjustment for each survey grid such that the data value differences in the grid overlap areas are minimized. The method spreads any inconsistencies between grids among all of the grid overlap areas and minimizes the introduction of long‐wavelength errors into the composite grid. This is an improvement on the conventional approach of joining grids sequentially. A comparison of leveled data over Western Australia with diurnally‐corrected long aeromagnetic traverses shows long‐wavelength errors of about 200 nT over distances of more than 5000 km. This is an improvement on the sequential grid‐joining method, which gives errors of about 450 nT over the same distance. The application of the method to a smaller area covered by good quality surveys resulted in long‐wavelength errors of about 30 nT over a distance of 1200 km. This is within the estimated accuracy of the original survey measurements. The new method is also fast—what used to take many weeks of effort can now be achieved in a matter of hours.

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Interpretation of airborne magnetic survey of Gabel Um Tineidba area, south eastern desert, Egypt

World Journal of Engineering ◽

10.1260/1708-5284.12.6.563 ◽

2015 ◽

Vol 12 (6) ◽

pp. 563-576

Author(s):

Tharwat H. Abdel Hafeez

Keyword(s):

Analytical Signal ◽

Eastern Desert ◽

Structural Features ◽

Geological Mapping ◽

Magnetic Data ◽

Magnetic Survey ◽

Aeromagnetic Survey ◽

Reasonable Proportion ◽

The Cost ◽

Airborne Magnetic

The study area is regionally covered by rock exposures ranging in age from the Precambrian to Quaternary. The aeromagnetic survey is a useful tool that help in geological mapping, providing information at a reasonable proportion of the cost of ground mapping. The reduced to the northern magnetic pole (RTP) map was separated into regional and residual magnetic component maps by the computed power spectrum of the magnetic data. The estimated mean depths of both regional and residual magnetic sources were found to be 2510 m and 383 m respectively. Also, two advanced techniques were used to analyze the depth magnetic data. These methods are analytical signal (AS) and source parameter imaging (SPI). The results of average depth estimates both methods (–950 m). These depth values were helped -to great extent- for define the direction of throw for the interpreted faults in the basement tectonic map. The statistical analysis shows that, most of the welldeveloped structural features are oriented mostly in the N-S, NNE-SSW, NW-SE and NNWSSE trending faults are considered the main trends affecting the distribution of the radioactive minerals.

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A stable downward continuation of airborne magnetic data: A case study for mineral prospectivity mapping in Central Iran

Computers & Geosciences ◽

10.1016/j.cageo.2012.11.006 ◽

2013 ◽

Vol 52 ◽

pp. 269-280 ◽

Cited By ~ 36

Author(s):

Maysam Abedi ◽

Ali Gholami ◽

Gholam-Hossain Norouzi

Keyword(s):

Downward Continuation ◽

Central Iran ◽

Magnetic Data ◽

Mineral Prospectivity Mapping ◽

Mineral Prospectivity ◽

Prospectivity Mapping ◽

Airborne Magnetic

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Automatic Detection of UXO from Airborne Magnetic Data Using a Neural Network

10.4133/1.2922956 ◽

2001 ◽

Cited By ~ 1

Author(s):

Ahmed Salem ◽

T. Jeffrey Gamey ◽

Dhananjay Ravat ◽

Keisuke Ushijima

Keyword(s):

Neural Network ◽

Automatic Detection ◽

Magnetic Data ◽

Airborne Magnetic

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Connecting onshore-offshore Campos Basin structures: Interpretation of high-resolution airborne magnetic data

Interpretation ◽

10.1190/int-2014-0007.1 ◽

2014 ◽

Vol 2 (4) ◽

pp. SJ35-SJ45 ◽

Cited By ~ 5

Author(s):

Juarez Lourenço ◽

Paulo T. L. Menezes ◽

Valeria C. F. Barbosa

Keyword(s):

Source Rocks ◽

Magnetic Data ◽

Data Sets ◽

Hydrocarbon Migration ◽

Data Set ◽

Campos Basin ◽

Turbidite Sedimentation ◽

Edge Detection Method ◽

Transfer Faults ◽

Airborne Magnetic

We interpreted northwest-trending transfer faults whose extensions are not entirely mapped in the Precambrian basement of the onshore and offshore Campos Basin. To enhance the subtle northwest–southeast lineaments not clearly seen in the total-field data, we reprocessed and merged two airborne magnetic data sets aiming at producing a single merged magnetic data set. Next, we applied a directional filter to these integrated magnetic data. Finally, we applied a multiscale edge detection method to these filtered data. This combination allowed the detection of edges and ridges that are used to produce several northwest–southeast lineations. We interpreted these northwest-trending lineations as magnetic expressions of transfer faults that cut across the onshore adjacent basement of the Campos Basin to the shallow and deep Campos Basin waters. These interpreted northwest-trending faults suggested the continuity of the known northwest-striking transfer faults in the deep Campos Basin waters toward the shallow Campos Basin waters and the adjacent continent. Moreover, our interpreted northwest-trending faults revealed the control of several known oilfields in the Campos Basin. This result supported the hypothesis of the influence of the northwest–southeast-trending transfer faults on the petroleum system of Campos Basin, which were reactivated in the Tertiary providing a pathway for the turbidite sedimentation, reworking, and redistribution of several deepwater reservoirs. In addition, it was hypothesized that this faulting system controlled the hydrocarbon migration paths from the presalt source rocks through salt windows into basal suprasalt layers.

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