Journal articles: 'Aeromagnetics'

1

Gunn, Peter. "Aeromagnetics locates prospective areasandprospects." Leading Edge 17, no. 1 (January 1998): 67–69. http://dx.doi.org/10.1190/1.1437828.

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Rigoti, Augustinho, Antonio L. Padilha, F. H. Chamalaun, and Nalin B. Trivedi. "Effects of the equatorial electrojet on aeromagnetic data acquisition." GEOPHYSICS 65, no. 2 (March 2000): 553–58. http://dx.doi.org/10.1190/1.1444750.

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In recent years, considerable advances have taken place in aeromagnetic surveying. These improvements involved data acquisition (instruments and survey design), processing, and interpretation. In addition to improved spatial resolution, the high‐resolution aeromagnetics, as applied to oil exploration, attempts to resolve very low amplitude (1 nT or even subnanotesla) magnetic features (Paterson and Reeves, 1985). These features are caused by weak intra‐sedimentary magnetic sources of magnetite and pyrrhotite, which could have been formed as a result of hydrocarbon seepage (e.g., Reynolds et al., 1990, 1991). For such small spatial variations to be meaningful, it is required that similar temporal and spatial variations due to external sources be corrected accordingly.

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Withers, Robert, Dwight Eggers, Thomas Fox, and Terry J. Crebs. "Reply by the authors to N. C. Steenland." GEOPHYSICS 61, no. 3 (May 1996): 915. http://dx.doi.org/10.1190/1.1487023.

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The comments made by N. C. Steenland address issues of the aeromagnetic interpretation and gravity data inconsistencies. These comments will be addressed individually. The authors are very familiar with the method of aeromagnetic exploration having used it in various countries, geologic environments and applications. The technique is extremely powerful when used appropriately, and magnetics were not discounted summarily. In any paper on exploration we believe it is important that all results be discussed, and a worse disservice to the industry would have been to ignore aeromagnetics. Indeed, we would have expected criticism had we not reported on our findings about the applicability of magnetics on the Columbia River Basalts (CRB). It is our experience that working with other basalts of different ages and sources, such as the Snake River Basalt example discussed by the reviewer, may not be a guarantee of obtaining appropriate interpretations elsewhere.

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Komolafe, Akinola Adesuji, Zacharia Njuguna Kuria, Tsehaie Woldai, Marleen Noomen, and Adeleye Yekini Biodun Anifowose. "Integrated Remote Sensing and Geophysical Investigations of the Geodynamic Activities at Lake Magadi, Southern Kenyan Rift." International Journal of Geophysics 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/318301.

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The tectonic lineaments and thermal structure of Lake Magadi, southern Kenyan rift system, were investigated using ASTER data and geophysical methods. Five N-S faults close to known hot springs were identified for geoelectric ground investigation. Aeromagnetic data were employed to further probe faults at greater depths and determine the Curie-point depth. Results indicate a funnel-shaped fluid-filled (mostly saline hydrothermal) zone with relatively low resistivity values of less than 1 Ω-m, separated by resistive structures to the west and east, to a depth of 75 m along the resistivity profiles. There was evidence of saline hydrothermal fluid flow toward the surface through the fault splays. The observed faults extend from the surface to a depth of 7.5 km and are probably the ones that bound the graben laterally. They serve as major conduits for the upward heat flux in the study area. The aeromagnetics spectral analysis also revealed heat source emplacement at a depth of about 12 km. The relative shallowness implies a high geothermal gradient evidenced in the surface manifestations of hot springs along the lake margins. Correlation of the heat source with the hypocenters showed that the seismogenetic zone exists directly above the magmatic intrusion, forming the commencement of geodynamic activities.

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Grant, F. S. "Aeromagnetics, geology and ore environments, II. Magnetite and ore environments." Geoexploration 23, no. 3 (September 1985): 335–62. http://dx.doi.org/10.1016/0016-7142(85)90002-x.

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Nathan, D., A. Aitken, E. J. Holden, and J. Wong. "Imaging sedimentary basins from high-resolution aeromagnetics and texture analysis." Computers & Geosciences 136 (March 2020): 104396. http://dx.doi.org/10.1016/j.cageo.2019.104396.

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7

Tarlowski, C., and I. Koch. "On the problem of estimating the depth to the magnetic basement." GEOPHYSICS 53, no. 10 (October 1988): 1362–63. http://dx.doi.org/10.1190/1.1442415.

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In many applications in aeromagnetics, the estimation of the depth to the crystalline magnetic basement is of great importance. Of many approaches to this problem, the most widely applied appear to be based upon Fourier analysis (see Ruotoistenmäki, 1987) or on fitting hypothetical models to observed data using a least‐squares principle (for example, Leite and Leão, 1985). Recently, some interest has been focused on direct approaches to the problem (Strakhov and Brodsky, 1986; Koch and Tarlowski, 1986; and Jonca and Vogel, 1987).

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Heath, D. H., V. S. Clarke, and A. N. Bint. "High Resolution Aeromagnetics Clarifies Structuring in the Vlaming Sub-Basin, Western Australia." Exploration Geophysics 24, no. 3-4 (September 1993): 535–41. http://dx.doi.org/10.1071/eg993535.

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Kuras, Agnieszka, Björn H. Heincke, Sara Salehi, Christian Mielke, Nicole Köllner, Christian Rogass, Uwe Altenberger, and Ingunn Burud. "Integration of Hyperspectral and Magnetic Data for Geological Characterization of the Niaqornarssuit Ultramafic Complex in West-Greenland." Remote Sensing 14, no. 19 (September 29, 2022): 4877. http://dx.doi.org/10.3390/rs14194877.

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The integration of imaging spectroscopy and aeromagnetics provides a cost-effective and promising way to extend the initial analysis of a mineral deposit. While imaging spectroscopy retrieves surface spectral information, magnetic responses are used to determine magnetization at both shallower and greater depths using 2D and 3D modeling. Integration of imaging spectroscopy and magnetics improves upon knowledge concerning lithology with magnetic properties, enhances understanding of the geological origin of magnetic anomalies, and is a promising approach for analyzing a prospective area for minerals having a high iron-bearing content. To combine iron diagnostic information from airborne hyperspectral and magnetic data, we (a) used an iron absorption feature ratio to model pseudo-magnetic responses and compare them with the measured magnetic data and (b) estimated the apparent susceptibility along the surface by some equivalent source modeling, and compared them with iron ratios along the surface. For this analysis, a Modified Iron Feature Depth index was developed and compared to the surface geochemistry of the rock samples in order to validate the spectral information of iron. The comparison revealed a linear increase in iron absorption feature depths with iron content. The analysis was performed by empirically modeling the statistical relationship between the diagnostic absorption features of hyperspectral (HS) image spectra of selected rock samples and their corresponding geochemistry. Our results clearly show a link between the spectral absorption features and the magnetic response from iron-bearing ultra/-mafic rocks. The iron absorption feature ratio of 𝐹𝑒3+/𝐹𝑒2+ integrated with aeromagnetic data (residual magnetic anomaly) allowed us to distinguish main rock types based on physical properties. This separation matches the lithology of the Niaqornarssuit complex, our study area in West Greenland.

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Roy Chowdhury, Priyanka, Darcy Christian, Keith Jones, Warwick Crowe, and Roger Miller. "Aeromagnetics assists Oil & Gas exploration in the Bedout Sub-basin, offshore Canning Basin." ASEG Extended Abstracts 2012, no. 1 (December 2012): 1–4. http://dx.doi.org/10.1071/aseg2012ab280.

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11

Elsirafe, A. M., and S. I. Rabie. "Contribution of aeromagnetics to structural mapping of Gabal Gattar area, North Eastern Desert, Egypt." Journal of African Earth Sciences (and the Middle East) 11, no. 1-2 (January 1990): 119–28. http://dx.doi.org/10.1016/0899-5362(90)90082-p.

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12

Grant, F. S. "Aeromagnetics, geology and ore environments, I. Magnetite in igneous, sedimentary and metamorphic rocks: An overview." Geoexploration 23, no. 3 (September 1985): 303–33. http://dx.doi.org/10.1016/0016-7142(85)90001-8.

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13

Mackey, Timothy, Kenneth Lawrie, Paul Wilkes, Tim Munday, Nadir de Souza Kovacs, Roslyn Chan, Dave Gibson, Colin Chartres, and Ray Evans. "Palaeochannels near West Wyalong, New South Wales: A case study in delineation and modelling using aeromagnetics." Exploration Geophysics 31, no. 1-2 (March 2000): 1–7. http://dx.doi.org/10.1071/eg00001.

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14

Whiting, T. H. "Aeromagnetics as an aid to geological mapping—a case history from the Arunta Inlier, Northern Territory." Australian Journal of Earth Sciences 33, no. 2 (June 1986): 271–86. http://dx.doi.org/10.1080/08120098608729364.

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15

Rao, D. Atchuta, H. V. Ram Babu, and G. D. J. Sivakumar Sinha. "Crustal structure associated with Gondwana graben across the Narmada-Son lineament in India: An inference from aeromagnetics." Tectonophysics 212, no. 1-2 (October 1992): 163–72. http://dx.doi.org/10.1016/0040-1951(92)90148-y.

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16

Ramarao, Ch, T. R. K. Chetty, A. Lingaiah, and V. Babu Rao. "Delineation of a greenstone belt using aeromagnetics, Landsat and photogeology — A case study from the South Indian Shield." Geoexploration 28, no. 2 (July 1991): 121–37. http://dx.doi.org/10.1016/0016-7142(91)90044-d.

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17

West, Gordon F., and Richard E. Ernst. "Evidence from aeromagnetics on the configuration of Matachewan dykes and the tectonic evolution of the Kapuskasing Structural Zone, Ontario, Canada." Canadian Journal of Earth Sciences 28, no. 11 (November 1, 1991): 1797–811. http://dx.doi.org/10.1139/e91-160.

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By digital image processing of federal–provincial aeromagnetic survey data for the south-central Superior Province, we have obtained an improved picture of the distribution of dykes in the huge Matachewan mafic dyke swarm (2454 Ma). We deduce from it a picture of post-emplacement deformation in the vicinity of the uplifted granulite gneisses of the Kapuskasing Structural Zone (KSZ). Matachewan dykes are emplaced in three subswarms. The two easterly subswarms are clearly truncated by the KSZ's eastern boundary faults. The western subswarm shows an open Z-bend as it crosses the KSZ, but it does not reveal any major fault offset. On the plausible assumption (supported by paleomagnetic data) that the subswarms were originally intruded radially, the horizontal strain suffered by the KSZ since emplacement of the dykes is mainly a northeast–southwest-trending band of dextral transcurrent deformation, which in the northeast is discontinuous and concentrated in a fault (horizontal offset 60–80 km) and in the southwest widens through a series of horsetail splays into an ~80 km wide zone of distributed strain. The KSZ is believed to have formed by a major, crustal-scale, thrust uplift along the KSZ's southeastern margin. Some thrusting is recorded by the dyke pattern, but this can account for only part of the ~20 km of differential uplift seen in the KSZ. Most likely, the mainly transcurrent deformation recorded by the dykes is a secondary event, and the primary period of thrust uplift predated dyke injection.

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Lebo, S. E., and D. A. Obi. "Application of aeromagnetics as a basin depth discriminating tool prior to seismic exploration: A case study of Central Niger Delta, Nigeria." Global Journal of Pure and Applied Sciences 23, no. 2 (November 30, 2017): 275. http://dx.doi.org/10.4314/gjpas.v23i2.8.

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19

Onderwaater, Jaap, Jan Wams, and Hans Potters. "Geophysics in Oman." GeoArabia 1, no. 2 (April 1, 1996): 299–324. http://dx.doi.org/10.2113/geoarabia0102299.

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ABSTRACT To date Petroleum Development Oman has acquired approximately 200,000 kilometers of 2-D and 20,000 square kilometers of 3-D seismic data. Five 3-D and one 2-D crews are operated by contractors. For 3-D surveys PDO uses 2 vibrator source groups recording a “double zig-zag”. The vibrators have GPS systems. The standard spread consists of 4 receiver lines of 120 active channels, spaced 200 meters apart, with receiver spacing of 50 meters. Bin size is 25 by 25 meters, multiplicity is 60 fold and the active spread is 6 kilometers. Most of the seismic data is processed inhouse by CGG. Additionally PDO uses proprietary software for bench-marking, training and attribute studies. Recent lines recorded with vibroseis, rather than thumper, and long offsets (4 to 6 km compared to 2 km) have improved both shallow (1 to 1.5 second) and deep reflections including sub-salt events (>2.5 second). Improved data quality has better imaged exploration targets (e.g. post-salt Haima and intra-salt Athel) and reservoir geometry (e.g. Alkhlata and Gharif). Proper imaging of the Athel silicilyte may require 3-D pre-stack depth migration. The application of other geophysical techniques including gravity, aeromagnetics, seismic attribute analysis and borehole geophysics has also proven useful, particularly where conventional seismic data quality is poor.

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NAZIH, Mohamed, Mohamed GOBASHY, Sultan ARAFFA, Khaled Soliman SOLIMAN, and Ahmed ABDELHALIM. "Geophysical studies to delineate groundwater aquifer in arid regions: A case study, Gara Oasis, Egypt." Contributions to Geophysics and Geodesy 52, no. 4 (December 12, 2022): 517–64. http://dx.doi.org/10.31577/congeo.2022.52.4.2.

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Groundwater is an important factor in establishing new urban communities, especially in coastal arid and semi-arid regions. Egypt is one of the world's driest countries, with hyper-arid territory accounting for 86% of the total area and arid and semi-arid terrain accounting for the rest. The present work aims to demonstrate the powerful integration of geophysical techniques to assess groundwater potentiality and suitability in Gara Oasis (GO), which describes a good example of Egypt's strategic southern extension of its arid north-western coast. Geophysical methods, including electrical resistivity and aeromagnetics, were used to evaluate groundwater resources. The study region reduced to pole total magnetic intensity map is subjected to digital filters that include derivatives, analytic signal, and tilt angle. The possible structures controlling the shallow and deep aquifers are delineated and integrated with geoelectric results. Moreover, two magnetic tomography sections are constructed to show the subsurface distribution of magnetic susceptibilities and formation boundaries. Ten vertical electric soundings (VESs) are measured and used in this study to construct four geoelectrical cross-sections. According to the results, Gara's commonly calculated subsurface resistivity model comprises six major resistivity layers. The 5th layer, in particular, is composed of Fractured dolomitic Limestone and represents a possible promising shallow aquifer. Moreover, as evidenced by various magnetic data filters, the shallow (Miocene carbonate) and deep (Nubian sandstone) aquifers are structurally controlled and regulated by a system of faults or contacts. These contacts trends NW–SE, E–W, and NE–SW as common trends emerged from the total derivative and tilt maps. Results suggest that the central part (N–S zone) together with the western side of Gara, have the most notable aquifer possibility demanded future improvement strategies.

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Yu, Ping, Fengyi Bi, Jian Jiao, Xiao Zhao, Shuai Zhou, and Zhenning Su. "An Aeromagnetic Compensation Algorithm Based on a Residual Neural Network." Applied Sciences 12, no. 21 (October 24, 2022): 10759. http://dx.doi.org/10.3390/app122110759.

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Aeromagnetic compensation is a crucial step in the processing of aeromagnetic data. The aeromagnetic compensation method based on the linear regression model has poorer fitting capacity than the neural network aeromagnetic compensation algorithm. The existing gradient updating neural network-based aeromagnetic compensation algorithm is subject to the problem that the gradient disappears during the backpropagation process, resulting in poor fitting ability and affecting aeromagnetic compensation accuracy. In this paper, we propose a neural network compensation algorithm with strong fitting ability: residual backpropagation neural network (Res-bp). The algorithm realizes the cross-layer propagation of the gradient through a residual connection so that the network not only preserves the original information but also acquires additional information during training, successfully solving the problem of gradient disappearance and boosting the network’s fitting capacity. The algorithm is applied to the data collected by unmanned aerial vehicles (UAVs) to verify its effectiveness. The results show that the improvement ratio is improved compared with the traditional neural network, demonstrating that the algorithm has a significant compensation effect on aeromagnetic interference and improves the quality of aeromagnetic data.

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Kowalik, W. S., and W. E. Glenn. "Image processing of aeromagnetic data and integration with Landsat images for improved structural interpretation." GEOPHYSICS 52, no. 7 (July 1987): 875–84. http://dx.doi.org/10.1190/1.1442358.

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Digital image processing of aeromagnetic data from three mineral prospects significantly improved the existing structural interpretations that were made from contour maps of the aeromagnetic data. Useful image‐processing techniques include (1) presentation as small‐scale, gray‐level images, (2) local contrast enhancement, (3) artificial illumination, and (4) directional filtering. Digital processing also enables direct comparison between Landsat data and aeromagnetic data. Interpretations were improved by the study of the integrated data sets. Images of aeromagnetic data from one prospect in a Precambrian granite‐greenstone terrane show major folds and faults that were not previously recognized from contour maps of the aeromagnetic data. A Landsat Multispectral Scanner (MSS) image shows the subtle surface expression of two folds. The newly identified structures point to additional prospective ground in the search for volcanogenic massive sulfide deposits in the area. Aeromagnetic data from a second prospect are complicated by a young, north‐south striking, strongly magnetic, diabase dike swarm. Directional filtering and artificial illumination of the aeromagnetic data effectively remove the response of the dikes and enhance the earlier structural and lithologic features. The combined interpretation of illuminated aeromagnetic and registered Landsat Thematic Mapper (TM) images for a third prospect added several significant faults that were previously unrecognized from separate interpretations of contour maps of aeromagnetic data and the Landsat image.

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Chandler, Val W., and David L. Southwick. "Aeromagnetic Minnesota." Eos, Transactions American Geophysical Union 71, no. 11 (1990): 329. http://dx.doi.org/10.1029/eo071i011p00329-01.

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Hood, Peter J., and Dennis J. Teskey. "Aeromagnetic gradiometer program of the Geological Survey of Canada." GEOPHYSICS 54, no. 8 (August 1989): 1012–22. http://dx.doi.org/10.1190/1.1442726.

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During the past two decades, the Geological Survey of Canada Aeromagnetic Survey Group, consisting of geophysicists, electronic engineers, technicians, and computer scientists, developed the aeromagnetic gradiometer technique for mineral exploration. The same group ran the aeromagnetic survey program in Canada, perhaps the largest such continuing aeromagnetic survey program in the world. In 1973, fabrication commenced on an inboard vertical gradiometer system on the GSC Queenair aeromagnetic survey aircraft. During the period 1978–1981, a number of experimental gradiometer surveys were carried out by the Geological Survey of Canada to demonstrate the efficacy of the aeromagnetic gradiometry technique as a geologic mapping tool in mineral exploration programs. Because of a need for aeromagnetic gradiometer surveys in the topographically rugged Gaspé Peninsula of Quebec, the GSC began in 1983 to foster the development of helicopter‐borne gradiometer systems through R and D contracts. Four companies responded and built towed‐boom helicopter gradiometer systems which have now been used in surveys in four eastern provinces. It is clear that the aeromagnetic gradiometer technique combined with VLF EM is an excellent geophysical tool to improve the accuracy of detailed geologic mapping for mineral exploration programs. VLF EM is an inexpensive add‐on that materially improves the geologic mapping capability of the airborne system. The product in color pixel form is in essence a pseudogeologic map and it is presently being employed as such.

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Zhou, Shuai, Changcheng Yang, Zhenning Su, Ping Yu, and Jian Jiao. "An Aeromagnetic Compensation Algorithm Based on Radial Basis Function Artificial Neural Network." Applied Sciences 13, no. 1 (December 22, 2022): 136. http://dx.doi.org/10.3390/app13010136.

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Aeromagnetic exploration is a magnetic exploration method that detects changes of the earth’s magnetic field by loading a magnetometer on an aircraft. With the miniaturization of magnetometers and the development of unmanned aerial vehicles (UAV) technology, UAV aeromagnetic surveying plays an increasingly important role in mineral exploration and other fields due to its advantages of low cost and safety. However, in the process of aeromagnetic measurement data, due to the ferromagnetic material of the aircraft itself and the change of flight direction and attitude, magnetic field interference will occur and affect the measurement of the geomagnetic field by the magnetometer. The work of aeromagnetic compensation is to compensate for this part of the magnetic interference and improve the magnetic measurement accuracy of the magnetometer. This paper focused on the problems of UAV aeromagnetic survey data processing and improved the accuracy of UAV based aeromagnetic data measurement. Based on the Tolles–Lawson model, a numerical simulation experiment of magnetic interference of UAV-based aeromagnetic data was carried out, and a radial basis function (RBF) artificial neural network (ANN) algorithm was proposed for the first time to compensate the aeromagnetic data. Compared with classical backpropagation (BP) ANN, the test results of the synthetic data and real measured magnetic data showed that the RBF-ANN has higher compensation accuracy and stronger generalization ability.

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Zhang, Yao, Yu-Xin Zhao, and Shuai Chang. "An Aeromagnetic Compensation Algorithm for Aircraft Based on Fuzzy Adaptive Kalman Filter." Journal of Applied Mathematics 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/405671.

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In order to ensure the effectiveness of geomagnetic navigation, as the foundation, the precise measurement of geomagnetic field must be guaranteed; namely, aircraft aeromagnetic compensation is worthy of being further studied. In this paper, the classical aircraft aeromagnetic compensation algorithm based on Leliak Model is analyzed and an aircraft aeromagnetic compensation algorithm based on fuzzy adaptive Kalman filter is proposed, which is a new approach for aircraft to achieve aeromagnetic compensation. Simulation results show that it has better compensation performance without relying on the aircraft attitude.

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Wu, Peilin, Qunying Zhang, Luzhao Chen, Wanhua Zhu, and Guangyou Fang. "Aeromagnetic Compensation Algorithm Based on Principal Component Analysis." Journal of Sensors 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/5798287.

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Aeromagnetic exploration is an important exploration method in geophysics. The data is typically measured by optically pumped magnetometer mounted on an aircraft. But any aircraft produces significant levels of magnetic interference. Therefore, aeromagnetic compensation is important in aeromagnetic exploration. However, multicollinearity of the aeromagnetic compensation model degrades the performance of the compensation. To address this issue, a novel aeromagnetic compensation method based on principal component analysis is proposed. Using the algorithm, the correlation in the feature matrix is eliminated and the principal components are using to construct the hyperplane to compensate the platform-generated magnetic fields. The algorithm was tested using a helicopter, and the obtained improvement ratio is 9.86. The compensated quality is almost the same or slightly better than the ridge regression. The validity of the proposed method was experimentally demonstrated.

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Florio, Giovanni, Salvatore Passaro, Giovanni de Alteriis, and Federico Cella. "Magnetic Anomalies of the Tyrrhenian Sea Revisited: A Processing Workflow for Enhancing the Resolution of Aeromagnetic Data." Geosciences 12, no. 10 (October 10, 2022): 377. http://dx.doi.org/10.3390/geosciences12100377.

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We propose a processing workflow to enhance the information content of aeromagnetic data. Our workflow is based on the downward continuation and subsequent L-transform of magnetic data. This workflow returns a map showing single highs, which correspond to the location of magnetic bodies, and does not need any a priori information about the source magnetization. We validated our workflow using the aeromagnetic anomalies of the Tyrrhenian Sea (Italy), by a comparison of the reprocessed aeromagnetic anomalies with high-resolution shipborne magnetic data in three selected areas. Through this comparison, we show that the proposed processing workflow of aeromagnetic data leads to more accurate interpretative results. Our results indicate that, in areas where higher resolution data are lacking, the reprocessing of aeromagnetic data according to our workflow may be as decisive as to suggest changes to their previous interpretations or, at least, useful for highlighting areas of special interest, deserving to be magnetically explored by a dedicated high-resolution shipborne survey.

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Vallée, Marc A., Larry Newitt, Régis Dumont, and Pierre Keating. "Correlation between aeromagnetic data rejection and geomagnetic indices." GEOPHYSICS 70, no. 5 (September 2005): J33—J38. http://dx.doi.org/10.1190/1.2057982.

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Predicting the rejection of aeromagnetic data would be a useful tool for aeromagnetic survey planning. To relate aeromagnetic survey requirements to geomagnetic activity monitoring and prediction, we analyzed the relationship between the rejection of aeromagnetic data as it is measured during surveys and the variations in existing geomagnetic indices. The magnetic data were collected at Canadian magnetic observatories during 2001 and covered the polar cap, auroral, and subauroral zones. The geomagnetic indices were global and local indices. The global indices included the Kp, ap, and Dst indices. The local indices were the three-component hourly ranges, the three-component maximum rate of change, and the Pc3 pulsation index. The goodness of fit was used to compare the results between the different indices at different locations. In general, there was some correlation between global geomagnetic indices and the rate of rejection of aeromagnetic data. Good correlation with a global index was obtained with the daily mean of the Ap index for a station located in the subauroral zone. The best correlation was obtained with local indices and particularly with the Pc3 index amplitude. From these results we conclude that forecasting Pc3 index amplitude would be a useful tool for planning aeromagnetic surveys.

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Ukaigwe, N. F. "Aeromagnetic Lineament Study in the Olary Province, South Australia." Global Tectonics and Metallogeny 4, no. 4 (August 4, 1995): 175–88. http://dx.doi.org/10.1127/gtm/4/1995/175.

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Liu, Yan-Xu, Wen-Yong Li, Zhi-Yuan Liu, Jia-Wei Zhao, An-Qi Cao, Shan Gao, Li-Jie Wang, and Cheng Yang. "Occurrence Characteristics of Magnetite and Aeromagnetic Prospecting Northeast of Hebei Province." Minerals 12, no. 9 (September 14, 2022): 1158. http://dx.doi.org/10.3390/min12091158.

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The occurrence characteristics of magnetite and the methods to quickly and effectively explore are important topics for ore prospecting in the new era. Taking northeast of Hebei Province of China as an example, this article aimed at an important strategic mineral of magnetite, then discussed its distribution characteristics and aeromagnetic exploration methods of it. First of all, we discuss the occurrence characteristics of sedimentary metamorphic and magmatic magnetite. Then, using the latest high-precision aeromagnetic data, combined with the geological outcrops, known iron deposits, ground magnetic surveys, and verification, we studied the relationship between the aeromagnetic anomalies and iron deposits through potential field conversion processing of the reduction to the pole, vertical derivative, upward continuation and residual anomaly, and the forward modeling and inversion methods of 2.5 D optimization fitting. Next, we summarize the metallogenic conditions and attributes of aeromagnetic prospecting and make magnetite predictions. In addition, it has suitable magnetite prospecting potential in the Laochenjia, Dabai, Jiuwuying, Beierying, Sidaogoumen, and Wuyingzi aeromagnetic anomaly regions. In conclusion, these regions have aeromagnetic anomalies with high amplitudes, large scales, and favorable metallogenic backgrounds for magmatic rocks, strata, and structures caused by concealed magnetite. In addition, they have great prospecting potential. Eventually, we hope this research method in this article can provide a reference for magnetite exploration in other areas with similar geological conditions.

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Peacock, S., and A. Reid. "Aeromagnetic data interpretation." Astronomy & Geophysics 54, no. 5 (September 18, 2013): 5.23. http://dx.doi.org/10.1093/astrogeo/att164.

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Jiang, Yi, Richard Holme, Sheng-Qing Xiong, Yong Jiang, Yan Feng, and Hai Yang. "Long-wavelength lithospheric magnetic field of China." Geophysical Journal International 224, no. 3 (October 12, 2020): 1780–92. http://dx.doi.org/10.1093/gji/ggaa490.

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SUMMARY We present new regional models, denoted CLAS, of the Chinese lithospheric field, combining the long-wavelength information provided by satellite-derived models: CHAOS-6, MF7, LCS-1 and NGDC720, and an extremely high-quality compilation of 97 994 aeromagnetic survey data with 10 km × 10 km resolution for shorter wavelength. The models are estimated using a depleted basis of global spherical harmonic functions centred on China. CLAS models are determined include harmonic degrees up to 400. Although some accuracy of aeromagnetic data is lost in order to balance the consistent of two data sets, the results show that CLAS models have a high correlation with the satellite models at low-degree terms (degree correlation > 0.9) but with more power at high-degree terms, reflecting more features of the lithospheric field in continental China. Examples of improvement include Changbai mountains, Sichuan Basin and Qinghai–Tibet Plateau. CLAS models have good agreement (coherence > 0.9) with Chinese aeromagnetic data at wavelength down to about 100 km (corresponding to spherical harmonic degree n = 400), filling the usual gap between satellite models and aeromagnetic data. Comparison with aeromagnetic data filtered at 100 km gives good agreement (correlation > 0.95). The residuals between CLAS models and aeromagnetic data are still large (rms > 70 nT), but with most of misfits arising from shorter wavelength fields that the model cannot fit at degree up to 400; such misfit could be reduced by increasing the model degree. We provide a geological example of how the inclusion of satellite data can change the geological conclusions that can be drawn from the magnetic information. However, the two data sets are not completely consistent, future models should start from a reanalysis of the aeromagnetic data and its line levelling to ensure consistency with the satellite model.

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Charles Ugwu Ugwueze, Nwofor, Victor Udokamma, Njoku, Ikechukwu Onyema, Jack Leah, Choko Chukwuemeka, and Ibeneme Sabinus Ikechukwu. "Qualitative Evaluation of Geophysical Aeromagnetic Data For River Anticline Around The River Niger Area In Koton-Karfi, Southern Bida Basin, Nigeria." Pacific International Journal 3, no. 2 (March 31, 2020): 29–32. http://dx.doi.org/10.55014/pij.v3i2.93.

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In this paper a qualitative evaluation of aeromagnetic data maps has been used to preliminarily support the formation of river anticlines beneath major rivers due to isostatic rebound as a result of deep river incision of surface and sub-surface overlying rocks. The regional gradients of digital high resolution aeromagnetic data were removed by polynomial fitting. This involved fitting a plane surface to the reduction to pole map of the aeromagnetic data by using multi-regression least square analysis of the Oasis Montaj 6.4 program. The regional field values from the plane surface are subtracted from the observed data to obtain the residual anomaly values. Power spectrum plots of aeromagnetic data of the study area produced a basement depth contour map. The basement depths of the south-western part of the study area revealed basement uplift with a depth range of 1.8 to 2.5km which lies beneath the Niger River area, SW of the study area, and depicts a river anticline.

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Thorning, L. "A decade of geophysical surveying in Greenland." Rapport Grønlands Geologiske Undersøgelse 128 (December 31, 1986): 123–33. http://dx.doi.org/10.34194/rapggu.v128.7929.

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A review is given of aeromagnetic, radiometric, seismic and gravimetric surveys over Greenland and adjacent offshore waters carried out during the decade 1975-85. The determination by aeromagnetic surveys of major boundaries in the Precambrian craton in ice-free areas and under the Inland Ice is discussed.

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Gruzdev, R. "Magnetic survey – ground technology, aeromagnetic survey on aircraft and unmanned aerial vehicles: a comparative analysis of the results (on the example of Eastern Transbaikalia)." Transbaikal State University Journal 26, no. 8 (2020): 6–15. http://dx.doi.org/10.21209/2227-9245-2020-26-8-6-15.

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The use of unmanned aerial vehicles (UAVs) in geophysical work is becoming a very popular area in the field of modern geological exploration. The advantage of unmanned systems is the optimal ratio of the quality of research results with a significant increase in work productivity and a decrease in cost. In this regard, the improvement of field techniques and the processing of UAV materials is of particular interest for exploration. On the subject, there are a number of unresolved issues that have been revealed to some extent as a result of the author’s comparison of ground-based magnetic exploration and aeromagnetic survey data. The purpose of the study was to assess the possibility of a full-fledged replacement of ground magnetic exploration work for aeromagnetic survey using unmanned aerial vehicles. The comparison of different types of magnetic survey is relevant, since on the basis of the actual material, the possibility of using an alternative more productive method – aeromagnetic survey using modern UAVs – instead of traditional expensive ground-based magnetic exploration works is analyzed. To compare the results of the studies, actual material obtained from field work on an area of 13,4 km2 was used. Based on the databases, maps of anomalous magnetic field and graphs on several geophysical profiles are built. Results of magnetic survey in air and ground versions are analyzed; correlation relationships between data of ground pedestrian magnetic survey and aeromagnetic system on An-3 and UAV aircraft are established. Based on the results of the study, correlation and determination coefficients were obtained, which indicate that geophysical methods on UAVs adequately occupy their place between classical aerogeophysics and ground-based pedestrian survey. Moreover, aeromagnetic survey using UAVs is able to replace pedestrian magnetic exploration during work at the same heights. Based on the results of the study, methodological recommendations for the production of aeromagnetic survey on UAVs were compiled

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Kivior, I., and D. Boyd. "THE INTERPRETATION OF AEROMAGNETIC SURVEYS FOR HYDROCARBON EXPLORATION." APPEA Journal 39, no. 1 (1999): 494. http://dx.doi.org/10.1071/aj98030.

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Aeromagnetic surveys have been generally regarded in petroleum exploration as a reconnaissance tool for major structures. They were used commonly in the early stages of exploration to delineate the shape and depth of the sedimentary basin by detecting the strong magnetic contrast between the sediments and the underlying metamorphic basement. Recent developments in the application of computer technology to the study of the earth's magnetic field have significantly extended the scope of aeromagnetic surveys as a tool in the exploration for hydrocarbons. In this paper the two principal methods used in the analysis and interpretation of aeromagnetic data over sedimentary basins are: 1) energy spectral analysis applied to gridded data; and, 2) automatic curve matching applied to profile data. It is important to establish the magnetic character of sedimentary and basement rocks, and to determine the regional magnetic character of the area by applying energy spectral analysis. Application of automatic curve matching to profile data can provide results from the sedimentary section and deeper parts of a basin. High quality magnetic data from an experimental aeromagnetic survey flown over part of the Eromanga/Cooper Basin has recently been interpreted using this new approach. From this survey it is possible to detect major structures such as highs and troughs in the weakly magnetic basement, as well as pick out faults, and magnetic layers in the sedimentary section. The results are consistent with interpretation from seismic and demonstrate that aeromagnetic data can be used to assist seismic interpretation, for example to interpolate between widely spaced seismic lines and sometimes to locate structures which can not be detected from seismic surveys. This new approach to the interpretation of aeromagnetic data can provide a complementary tool for hydrocarbon exploration, which is ideal for logistically difficult terrain and environmentally sensitive areas.

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Kim, Bona, Soocheol Jeong, Eunseok Bang, Seungwook Shin, and Seongjun Cho. "Investigation of Iron Ore Mineral Distribution Using Aero-Magnetic Exploration Techniques: Case Study at Pocheon, Korea." Minerals 11, no. 7 (June 22, 2021): 665. http://dx.doi.org/10.3390/min11070665.

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We present our aeromagnetic survey results from an investigation of the iron ore mineral distribution in Pocheon, Korea, in the west-central area of the Korean Peninsula. A manned aeromagnetic system using a helicopter for regional exploration and an unmanned aeromagnetic system using a multicopter for high-resolution exploration were used for the survey. The inversion results of the magnetic data confirmed the possibility of the existence of a new iron ore body. Drilling was carried out based on inversion results and drilling revealed amphibolite including iron ore, as indicated by a strong magnetic response. The position and depth of the iron ore were consistent with the interpretation results of the magnetic data.

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Cowan, D. R., M. Baigent, and S. Cowan. "Aeromagnetic Gradiometers-a Perspective." Exploration Geophysics 26, no. 2-3 (June 1, 1995): 241–46. http://dx.doi.org/10.1071/eg995241.

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Hardwick, C. D. "Aeromagnetic Gradiometry In 1995." Exploration Geophysics 27, no. 1 (March 1996): 1–11. http://dx.doi.org/10.1071/eg996001.

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Eaton, D., and K. Vasudevan. "Skeletonization of aeromagnetic data." GEOPHYSICS 69, no. 2 (March 2004): 478–88. http://dx.doi.org/10.1190/1.1707068.

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Skeletonization is a syntactic pattern‐recognition method that is applied to gridded data to produce an automatic line drawing, with an associated event catalog. Previous implementations of skeletonization have been tailored for seismic data. Here, we modify that technique to render it more suitable for other types of gridded data, with particular emphasis on aeromagnetic maps. A modification from previous schemes is the use of a two‐pass approach, to reduce the effects of an otherwise problematic directional bias that discriminates against events oriented parallel to columns of the grid. The method can be used effectively for filtering aeromagnetic data on the basis of strike direction, event linearity, event amplitude, and polarity. It is based on the delineation of peak‐trough pairs (cycles), which are traced throughout the grid to form contiguous events. Cycles and events are characterized by attributes that include amplitude, polarity, and pulse width. Events are further characterized by length, average strike direction, and linearity. The event attributes are stored in a catalog, thus enabling one to perform attribute‐based analysis and data filtering. We illustrate our algorithm using two regional aeromagnetic examples from different parts of the Canadian Shield. The first, from the Great Slave Lake shear zone, is dominated by linear anomaly trends produced by faults and mafic dikes. The second, from the Manicouagan region of northeastern Quebec, contains abundant subcircular and arcuate anomaly patterns caused by large intrusive complexes and a meteorite impact structure.

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Farrelly, Brian, and Harald Elstad. "High-resolution aeromagnetic surveying." Journal of Applied Geophysics 34, no. 2 (December 1995): 138–39. http://dx.doi.org/10.1016/0926-9851(96)80866-4.

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Floyd, J. D., and G. S. Kimbell. "Magnetic and tectonostratigraphic correlation at a terrane boundary: the Tappins Group of the Southern Uplands." Geological Magazine 132, no. 5 (September 1995): 515–21. http://dx.doi.org/10.1017/s0016756800021178.

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AbstractProminent aeromagnetic anomalies around Ballantrae in southwest Scotland have long been associated with extensive outcrops of basic/ultrabasic igneous rocks in the Midland Valley terrane. However, recent reprocessing of data from a 1978 detailed aeromagnetic survey has demonstrated excellent correlation between discrete aeromagnetic features and certain magnetic greywacke formations within the early Caradoc Tappins Group. This heterogeneous unit forms the oldest and most northwesterly tectonostratigraphic tract in the Southern Uplands terrane and is characterized by relatively high detrital magnetite(and serpentinite) content and elevated values for Cr and Ni. This suggests original close sedimentary links with an ophiolitic terrane not unlike the presently adjacent Ballantrae Complex (or its extensive along-strike correlatives), a consideration which has important implications for terrane reconstructions in this region.

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Feng, Yongqiang, Qimao Zhang, Yaoxin Zheng, Xiaodong Qu, Fang Wu, and Guangyou Fang. "An Improved Aeromagnetic Compensation Method Robust to Geomagnetic Gradient." Applied Sciences 12, no. 3 (January 29, 2022): 1490. http://dx.doi.org/10.3390/app12031490.

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Aeromagnetic surveys play an important role in many fields, for example, archaeology, anti-submarine warfare, and geophysical exploration. Being in the geomagnetic field, the aircraft generates a great deal of magnetic interference, resulting in bad performance during detection surveys. Thus, it is necessary and important to perform aeromagnetic compensation in advance. Conventional aeromagnetic compensation methods consider that the geomagnetic gradient is approximately zero after bandpass filtering, bringing about the inaccuracy of compensation coefficients. To address this issue, an improved aeromagnetic compensation method robust to geomagnetic gradient is proposed. In this study, the International Geomagnetic Reference Field (IGRF) model was employed to model the geomagnetic gradient. Then, the estimated geomagnetic gradient was subtracted from the measured data, which improved the accuracy of the compensation equations. Field experiments were conducted to verify the effectiveness of the proposed method. The experimental results show that compared to the traditional method, the compensation performance of the proposed method was improved by 152% to 329%. For the level flight, the standard deviation of residual noise after compensation can be as low as 3.3pT. The results indicate that the proposed method can significantly improve the compensation effect, showing great benefits for weak magnetic anomaly detection.

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Grauch, V. J. S., and C. A. Ruleman. "Identifying Buried Segments of Active Faults in the Northern Rio Grande Rift Using Aeromagnetic, LiDAR, and Gravity Data, South-Central Colorado, USA." International Journal of Geophysics 2013 (2013): 1–26. http://dx.doi.org/10.1155/2013/804216.

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Combined interpretation of aeromagnetic and LiDAR data builds on the strength of the aeromagnetic method to locate normal faults with significant offset under cover and the strength of LiDAR interpretation to identify the age and sense of motion of faults. Each data set helps resolve ambiguities in interpreting the other. In addition, gravity data can be used to infer the sense of motion for totally buried faults inferred solely from aeromagnetic data. Combined interpretation to identify active faults at the northern end of the San Luis Basin of the northern Rio Grande rift has confirmed general aspects of previous geologic mapping but has also provided significant improvements. The interpretation revises and extends mapped fault traces, confirms tectonic versus fluvial origins of steep stream banks, and gains additional information on the nature of active and potentially active partially and totally buried faults. Detailed morphology of surfaces mapped from the LiDAR data helps constrain ages of the faults that displace the deposits. The aeromagnetic data provide additional information about their extents in between discontinuous scarps and suggest that several totally buried, potentially active faults are present on both sides of the valley.

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Gregotski, Mark E., Olivia Jensen, and Jafar Arkani‐Hamed. "Fractal stochastic modeling of aeromagnetic data." GEOPHYSICS 56, no. 11 (November 1991): 1706–15. http://dx.doi.org/10.1190/1.1442983.

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We present a convolutional linear data model for the processing of aeromagnetic data. The model assumes that the data derive from the superposition of a deterministic system function and a stochastic innovation process. The two‐dimensional system function is described by a four‐pass autoregressive (AR) filtering procedure and is radially symmetric. The innovation process represents the distribution of near‐surface magnetic sources and is modeled as a spectrally self‐scaling (i.e., fractal) noise. The appropriate fractal noise is determined by examining aeromagnetic power spectra from various areas of the Canadian Shield. The AR coefficients of the system are determined using an iterative deconvolution procedure. For computational convenience, we make the traditional assumption of a spectrally white innovation, but modify the data prior to its deconvolution by prewhitening the assumed fractal innovation. The recovered system function is then removed from the original data in order to produce the fractal stochastic surface. This deconvolution technique is applied to two aeromagnetic maps from northeastern Ontario, Canada and is shown to be effective in delineating lithologies and enhancing magnetic field anomalies. We propose a particular statistical description of near‐surface magnetic sources for modeling aeromagnetic data in “shield‐type” geologic environments.

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Sánchez, Matías G., Murray M. Allan, Craig J. R. Hart, and James K. Mortensen. "Extracting ore-deposit-controlling structures from aeromagnetic, gravimetric, topographic, and regional geologic data in western Yukon and eastern Alaska." Interpretation 2, no. 4 (November 1, 2014): SJ75—SJ102. http://dx.doi.org/10.1190/int-2014-0104.1.

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Aeromagnetic lineaments interpreted from reduced-to-pole (RTP) magnetic grids were compared with gravity, topography, and field-based geologic maps to infer regional structural controls on hydrothermal mineral occurrences in a poorly exposed portion of the North American Cordillera in western Yukon and eastern Alaska. High-frequency and variable-intensity aeromagnetic lineaments corresponding to discontinuities with an aeromagnetic domain change were interpreted as steep-dipping and either magnetite-destructive or magnetite-additive faults. These structures were interpreted to be predominantly Cretaceous in age and to have formed after the collision of the Intermontane terranes with the ancient Pacific margin of North America. To demonstrate the reliability of the aeromagnetic interpretation, we developed a multidata set stacking methodology that assigns numeric values to individual lineaments depending on whether they can be traced in residuals and first vertical derivative of RTP aeromagnetic grids, isostatic residual gravity grids, digital topography, and regional geologic maps. The sum of all numeric values was used to estimate the likelihood of the aeromagnetic lineament as a true geologic fault. Fault systems were interpreted from zones of lineaments with high spatial density. Using this procedure, 10 major northwest-trending fault systems were recognized. These were oriented subparallel to the regional Cordilleran deformation fabric, the mid-Cretaceous Dawson Range magmatic arc, and well-established crustal-scale dextral strike-slip fault systems in the area. These orogen-parallel fault systems were interpreted to play a structural role in the emplacement of known porphyry Cu-Au and epithermal Au systems of mid-Cretaceous (115–98 Ma) and Late Cretaceous (79–72 Ma) age. The procedure also identified seven northeast-trending, orogen-perpendicular fault-fracture systems that are prominent in eastern Alaska and exhibit sinistral-to-oblique extensional kinematics. These structures were interpreted to govern the emplacement of Late Cretaceous (72–67 Ma) porphyry Mo- and Ag-rich polymetallic vein and carbonate replacement systems in the region.

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Grauch, V. J. S. "A new variable‐magnetization terrain correction method for aeromagnetic data." GEOPHYSICS 52, no. 1 (January 1987): 94–107. http://dx.doi.org/10.1190/1.1442244.

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Terrain effects in aeromagnetic data are produced by rugged, magnetic topography. These effects mimic the shape of topography and can often be so large that they obscure anomalies of interest. Thus it is desirable to remove terrain effects from aeromagnetic data in order to isolate the anomalies to be investigated. However, removal of aeromagnetic terrain effects has been a longstanding problem. Previously developed methods have succeeded only in certain, specific geologic situations. I present a new aeromagnetic terrain‐correction method that is superior to the previously developed methods for the general case. This method takes into account the highly variable magnetic properties of rocks and can remove terrain effects whether the sources of interest are shallow or deep. The new method is based on the assumption that magnetic sources of interest are often geometrically unrelated to terrain. It finds the magnetization that gives a magnetic‐field residual with minimum correlation to terrain effects for a window of data within a grid of magnetic‐field values. By repeating the calculation for windows covering the entire grid, a grid of variable‐magnetization values is produced which is combined with topography to calculate a magnetic‐terrain correction. The variable‐magnetizaton method was extensively tested using theoretical models (where the answer is known) and using real data from the Lake City caldera area in the San Juan Mountains of southern Colorado. The tests demonstrated the method’s effectiveness in removing terrain effects from aeromagnetic data. Valid terrain corrections were not obtained where anomalies of interest correlated with terrain effects. However, these places are readily recognizable and easily corrected by editing some of the magnetization values.

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Yigui, Lionel Cedric, Theophile Ndougsa-Mbarga, Arsène Meying, and Olivier Ulrich-Igor Owono-Amougou. "Detection of sub-surface fractures based on filtering, modeling, and interpreting aeromagnetic data in the Deng Deng – Garga Sarali area, Eastern Cameroon." Open Geosciences 14, no. 1 (January 1, 2022): 646–62. http://dx.doi.org/10.1515/geo-2022-0357.

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Abstract The aeromagnetic anomalies existing in the Deng Deng – Garga Sarali region in Eastern Cameroon were filtered for a structural study of the region’s subsoil. This study presents the results of lineaments and fractures extracted by aeromagnetic image processing methods and compared with scientific data to obtain potential terrain models in the study area. The methodological approach used is based on the filtering of aeromagnetic image by using the analytical signal, the Euler deconvolution, and 2D3/4 modeling, to establish the maps of the lineaments and faults of the study area and their characteristics, and also to propose three models from three previously chosen profiles. Analytical signal and Euler deconvolution techniques have been applied to aeromagnetic anomalies to highlight the relationship between the depth and the source of magnetic anomalies, two parameters whose importance in geoexploration and modeling of the body is essential. We identified the potential contacts by interpretation of the deep Euler anomalies, these are highlighted on the basis of a certain similarity between the maps of the total magnetic field, the map of the analytical signal, the map of the maxima of the gradient horizontal, and geological map. Euler’s map of solutions correlates well with the edges of certain superficial and deep causative bodies.

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Gapeev, D. N., M. I. Epov, A. A. Tishkin, A. P. Firsov, Ya V. Frolov, V. A. Ostanin, A. S. Kolesov, and Yu Yu Maletin. "Spline approximation of unequal aeromagnetic survey data with the use of UAV on spatially inhomogeneous networks when solving problems of archaeological exploration." Russian Journal of geophysical technologies, no. 3 (February 4, 2021): 18–30. http://dx.doi.org/10.18303/2619-1563-2020-3-18.

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The article discusses an approach to get a regular cube of data in context of aeromagnetic survey. It is based on spline approximation with nodes on an irregular grid in three-dimensional space. To construct approximation spline, information on measurement errors is additionally used, which makes it possible to reduce the number of parameters as opposed to spline interpolation. This approach was tested on experimental aeromagnetic data from archaeological site Ivanovka-I.

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Journal articles on the topic 'Aeromagnetics'

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