Journal articles on the topic 'Aeromagnetic interpretations'
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1
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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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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Marlow, Christopher, Christine Powell, and Randel Cox. "Aeromagnetic Interpretations of the Crittenden County Fault Zone." Seismological Research Letters 92, no. 1 (December 2, 2020): 494–507. http://dx.doi.org/10.1785/0220200209.
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Abstract The Crittenden County fault zone (CCFZ) is a potentially active fault zone located within 25 km of Memphis, Tennessee, and poses a significant seismic hazard to the region. Previous research has associated the fault zone with basement faults of the eastern Reelfoot rift margin (ERRM) and described it as a northeast-striking, northwest-dipping reverse fault. However, we suggest that there is an incomplete understanding of the fault geometry of the CCFZ and the ERRM in this region due to significant gaps in seismic reflection profiles used to interpret the fault systems. To improve our understanding of the structure of both fault systems in this region, we apply two processing techniques to gridded aeromagnetic data. We use the horizontal gradient method on reduction-to-pole magnetic data to detect magnetic contacts associated with faults as this technique produces shaper gradients at magnetic contacts than other edge detection methods. For depth to basement estimations, we use the analytic signal as the method does not require knowledge of the remnant magnetization of the source body. We suggest that the CCFZ extends approximately 16 km farther to the southwest than previously mapped and may be composed of three independent faults as opposed to a continuous structure. To the northeast, we interpreted two possible faults associated with the ERRM that intersect the CCFZ, one of which has been previously mapped as the Meeman–Shelby fault. If the CCFZ and the eastern rift margin are composed of isolated fault segments, the maximum magnitude earthquake that each fault segment may generate is reduced, thereby, lowering the existing seismic hazard both fault systems pose to Memphis, Tennessee.
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Wise, Tom, Mark Pawley, and Rian Dutch. "Preliminary interpretations from the 2015 Coompana aeromagnetic survey." ASEG Extended Abstracts 2016, no. 1 (December 2016): 1–6. http://dx.doi.org/10.1071/aseg2016ab191.
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Pilkington, Mark, and Walter R. Roest. "Removing varying directional trends in aeromagnetic data." GEOPHYSICS 63, no. 2 (March 1998): 446–53. http://dx.doi.org/10.1190/1.1444345.
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Both qualitative and quantitative interpretations of aeromagnetic data can be hindered by the presence of magnetic anomalies caused by mafic dykes. Such anomalies obscure the magnetic signatures due to basement lithology and structure, and their effects will often dominate when automated interpretation methods are applied to gridded data sets. Since dyke swarms are often nonparallel, simple frequency‐domain strike‐sensitive filtering based on a single directional trend is not a viable method for removing their signatures. We use a coordinate transformation to project anomalies of various strikes onto one direction, which is then suppressed using a standard decorrugation method. The resulting grid is subsequently transformed back to the original projection. This approach is illustrated by the removal of the magnetic signature of the Proterozoic Mackenzie dyke swarm occurring in the Slave structural province, Northwest Territories, Canada.
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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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Aitken, A. R. A., E.-J. Holden, and M. C. Dentith. "Semiautomated quantification of the influence of data richness on confidence in the geologic interpretation of aeromagnetic maps." GEOPHYSICS 78, no. 2 (March 1, 2013): J1—J13. http://dx.doi.org/10.1190/geo2012-0033.1.
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Geologic interpretations of aeromagnetic maps are highly subjective but are rarely accompanied by a quantitative confidence assessment, which is a key limitation on the usefulness of the results. Here, we outline a method with which the relative level of data richness can be assessed quantitatively, leading to an improved understanding of spatial variations in interpretational confidence. Simple rules were used to quantify the likely influence of several major sources of uncertainty. These were: (1) the level of geologic constraint, using the local abundance of outcropping rock and the quality of geologic mapping; (2) the interpretability of the aeromagnetic data, considering the strength of edge-like features and the degree of directionality of these features, a proxy for structural complexity; (3) data collection and processing errors, including gridding errors, derived from the statistical error returned during kriging, and the influence of anisotropic line data collection on the detection of gradients. From these individual sources of uncertainty, an overall data richness map was generated through a weighted summation of these grids. Weightings were assigned so as to best match the result to the interpreter’s perception of interpretational confidence. This method produced a map of data richness, which reflects the opportunity that the data provided to the interpreter to make a correct interpretation. An example from central Australia indicated that the data influences were preserved over a moderate range of weighting factors, and that strong bias was required to override these. In addition to providing a confidence assessment, this method also provides a way to test the potential benefits of additional data collection.
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Pilkington, Mark, and Victoria Tschirhart. "Practical considerations in the use of edge detectors for geologic mapping using magnetic data." GEOPHYSICS 82, no. 3 (May 1, 2017): J1—J8. http://dx.doi.org/10.1190/geo2016-0364.1.
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Locating the edges of magnetized sources provides a fundamental tool in the geologic interpretation of magnetic field data. Much recent effort has been expended on developing improvements to existing edge-detection methods, resulting in purported increases in accuracy and continuity along edges, reduction of noise effects, and limiting the influences of variable depth to source, magnetization direction, and source dip. These endeavors are valuable and provide interpreters with a wider range of tools to carry out geologic interpretations of aeromagnetic data. Nevertheless, survey parameters such as flight height and line spacing impose limits on the quality of edge locations that can be achieved. Using model studies, we quantify the effects that source size, depth, and interference between sources have on calculated edge locations. Based on the known behavior of established edge detectors, we found that many of the newer approaches offer limited advantages over older methods. Consequently, we studied an example of field mapping of geologic contacts in the Canadian Shield, supported by aeromagnetic data, using calculation of a standard edge detector: the horizontal gradient magnitude of the total magnetic field or TF-hgm. Calculated edge locations estimated from this method appear sufficiently accurate and continuous to provide a solid basis on which the mapping campaign was based and executed successfully.
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Owono Amougou, Olivier Ulrich Igor, Théophile Ndougsa Mbarga, Arsène Meying, Jean Marcel Abate Essi, Jean Aimé Mono, Didier Pepogo Manvele, and Christian Gislain Leonel Ngah. "Interpretation of Aeromagnetic Data to Investigate Crustal Structures of the Contact Congo Craton - Pan-African Belt at the Eastern Cameroon." Earth Science Research 9, no. 2 (June 8, 2020): 48. http://dx.doi.org/10.5539/esr.v9n2p48.
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The collision between the Congo Craton and the Pan African fold belt of Central Africa had great impacts on the geological and tectonic points of view, notably the installation of several tectonic accidents such as faults, fractures, dikes, folds, domes. This aeromagnetic study is based on Paterson's aeromagnetic data interpretations through the use of multiple operators. These data were processed by Oasis Montaj software. The total magnetic intensity map reduced to the equator (RTE-TMI) shows important anomalies features the major important regional anomalies. Maps of the vertical gradient, analytical signal and tilt angle maps have meanwhile highlighted several short wavelength anomalies assimilated to folding, dykes, fractures or faults. The map of maxima upward to 2 km allowed to establish the structural map of the study area. It turns out that the different types of geological accidents follow ENE-WSW, ESE-WNW, NE-SW, NW-SE and even E-W and N-S directions. All these directions are very similar to the geological history of the area. Anything that seems to confirm that the study area was the scene of intense tectonic movements resulting from the collision between the Congo Craton and the Central Africa Fold Belt.
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Oladejo, Olagoke Peter, Theophilus Aanuoluwa Adagunodo, Lukman Ayobami Sunmonu, Moruffdeen Adedapo Adabanija, Charity Adaeze Enemuwe, and Patrick Omoregie Isibor. "Aeromagnetic mapping of fault architecture along Lagos–Ore axis, southwestern Nigeria." Open Geosciences 12, no. 1 (July 13, 2020): 376–89. http://dx.doi.org/10.1515/geo-2020-0100.
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AbstractA seismic wave is released when there is sudden displacement on a fault plane. The passage of this wave along the fault plane or within the lithosphere could result in ground shaking or vibration at the surface of the Earth. To provide a geophysical explanation to this phenomenon, the high-resolution aeromagnetic data of the sedimentary terrain and part of the Basement Complex of Southwestern Nigeria were processed and interpreted to provide fault architecture of the area, which could serve as conduit for the passage of seismic energy in the study area. High-resolution aeromagnetic data along the Lagos–Ore axis are processed for fault mapping in the study area. The reduced-to-equator (RTE) residual aeromagnetic data used were enhanced using the total horizontal derivative (THD) and upward continuation (UC) filtering techniques on Oasis Montaj 6.4.2 (HJ) software. The resultant maps were overlaid and compared with the plotted RTE residual maps for relevant interpretations. Varying signatures of magnetic anomalies are grouped into high (57.9–89.1 nT), intermediate (38.2–57.9 nT), and low (4.0–38.2 nT) magnetic intensities, which are associated with contracting basement rocks features. The obtained lineaments from the THD reveal areas of various deformations such as brittle, which is associated with faults/fractures, and ductile deformation, which is associated with folds of geological features. The faults, as depict by the UC map, reveal different depth ranges of 500–2250 m at the western side and 1,500–1,250 m at the northwestern area of the study. Since it has been on record that September 11, 2009, earth tremor of magnitude 4.4, with the epicenter at Allada, Bennin Republic, 128 km west of Lagos, Nigeria occurred within the study area, it can be inferred that the established geologic fault architecture could be responsible for the hazard and be part or synthetic to the Ifewara-Zungeru fault in Nigeria.
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Markov, Jelena, Claudio Delle Piane, Ernest Swierczek, Clive Foss, and Mohinudeen Faiz. "Structural interpretation of the Beetaloo Sub-basin, NT from nonseismic geophysical data." APPEA Journal 61, no. 2 (2021): 679. http://dx.doi.org/10.1071/aj20194.
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The Beetaloo Sub-basin is known for its vast unconventional hydrocarbon resources even though it is relatively underexplored. There is reasonably good coverage of 2D seismic within the sub-basin which is used as the basis for most structural interpretations. However, seismic quality varies, and it is occasionally deteriorated by the presence of basalts from the Kalkarindji suite and the karstic nature of the Gum Ridge formation. Aeromagnetic data, constrained by petrophysical logs are used, to map faults in the basalts of the Kalkarindji suite and their lateral extent to the South and the East of the sub-basin. The same structural elements are identified in the full tensor gravity gradiometry data. The top of this unit is observed in the electrical conductivity profiles, derived from Tempest data, in the NW part of the eastern sub-basin.
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Rasaq, Bello. "Structural Interpretations Inferred from a High Resolution Aeromagnetic (HRAM) Data over Parts of Onshore Niger Delta, Nigeria." International Journal of High Energy Physics 4, no. 3 (2017): 23. http://dx.doi.org/10.11648/j.ijhep.20170403.11.
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Steenfelt, Agnete, Henrik Stendal, Bo Møller Nielsen, and Thorkild M. Rasmussen. "Gold in central West Greenland – known and prospective occurrences." Geological Survey of Denmark and Greenland (GEUS) Bulletin 4 (July 20, 2004): 65–68. http://dx.doi.org/10.34194/geusb.v4.4787.
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In 2003, the Geological Survey of Denmark and Greenland (GEUS) completed a four-year project aimed at assessing the mineral potential of the Precambrian region of West Greenland between latitudes 66° and 70°15´N. The project was part of a contract between GEUS and the Ministry of the Environment, and involved compilation of existing geoscientific data, new geological mapping, field examinations of known and potential mineral occurrences, new chemical and isotope analyses, and data interpretation. The data compilation, available on a DVD (Schjøth et al. 2004), comprises regional, systematically acquired data sets presented in a Geographic Information System environment. Aeromagnetic, aeroradiometric, stream sediment and rock geochemical and gravity data, a digital elevation model and a satellite image are included, plus descriptions of 60 mineral occurrences. Evaluation of the mineral potential is based on interpretations of the compiled information as well as on earlier investigations by the Survey, the University of Copenhagen and commercial companies (see e.g. Stendal & Schønwandt 2003; Stendal et al. 2004). From an economic point of view, the potential for gold and diamonds is the most interesting in the investigated area. This paper summarises the evaluation of the gold potential; results of diamond-related investigations are reported separately (Jensen & Secher 2004, this volume).
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Silva, João B. C. "2-D magnetic interpretation using the vertical integral." GEOPHYSICS 61, no. 2 (March 1996): 387–93. http://dx.doi.org/10.1190/1.1443967.
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A magnetic interpretation method is presented which numerically computes the vertical integral of the observed total‐field anomaly along a profile. This transformed field is fitted by the vertical integral (also computed numerically) of the total‐field anomaly of an interpretation model using a standard, nonlinear, least‐squares estimation routine. The vertical integral transformation used here is similar to using a spatial domain pseudogravity operator after reducing the magnetic anomaly to the pole. The difference is that the reduction to the pole is not needed, so that the knowledge of the magnetization direction is not required. This method estimates the depth to a weakly magnetized basement that is intruded by strongly magnetized rocks. This method is best suited for the case where sills cut the overlying sediments and interfere with the magnetic signal from basement. Attempts to interpret isolated anomalies of stocks in the basement should take into account this kind of interference. The proposed method attenuates the effect of the shallow sources and produces a better lateral resolution than the upward continuation filter. Synthetic examples show that in interpreting the total‐field anomaly, the presence of shallow sources leads to underestimated depths to the basement. By using the vertical integral of the total‐field anomaly, on the other hand, depth estimates closer to the true values are obtained. The method is applied to aeromagnetic data from Amazon Basin, Brazil, and produces estimates for the basement depths that are consistent with the geological knowledge and with previous magnetic interpretations.
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Mariano, John, and William J. Hinze. "Structural interpretation of the Midcontinent Rift in eastern Lake Superior from seismic reflection and potential-field studies." Canadian Journal of Earth Sciences 31, no. 4 (April 1, 1994): 619–28. http://dx.doi.org/10.1139/e94-055.
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Integrated interpretations of potential-field and GLIMPCE and industry seismic reflection data in eastern Lake Superior reveal the structural and stratigraphic complexity of the Midcontinent Rift in this region. Projection of the Keweenaw fault into southeastern Lake Superior suggested by early potential-field studies is confirmed by seismic reflection data. Analysis of seismic data in conjunction with aeromagnetic anomalies and regional gravity data also reveals a continuous section of basalt in the footwall of the Keweenaw fault. The lateral dimensions of this section vary along the strike of the rift from the center of the basin towards the southern flank. Spatially extensive anticlinal and synclinal features, reverse faults and related drag folds imaged by the reflection and enhanced potential-field data attest to the influence of a late-stage compressional event in this region. East-northeast trending gradients and displacements associated with observed potential-field anomalies and fault traces mapped at the surface also indicate a degree of accommodation perpendicular to the strike of the rift. These trends parallel the prevalent tectonic grain in the adjacent Archean basement rocks, perhaps suggesting that structures within the rift were in part controlled by preexisting crustal features.
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Tschirhart, Victoria, and Sally J. Pehrsson. "New insights from geophysical data on the regional structure and geometry of the southwest Thelon Basin and its basement, Northwest Territories, Canada." GEOPHYSICS 81, no. 5 (September 2016): B167—B178. http://dx.doi.org/10.1190/geo2015-0586.1.
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Detailed analysis of gravity and aeromagnetic data covering the southwest Thelon Basin, Northwest Territories, Canada, has provided insight into basement geology that has significance to exploration for uranium and possibly other economic metals in a remote frontier region. Interpretation of basement geology has been constrained by the calibration of gravity and magnetic signatures with Precambrian geology adjacent to the basin and sparse seismic data within the basin, creating the first basement geologic map of the southwest Thelon Basin. The basement to the overlying sedimentary units is dominated by magnetic felsic and mafic bodies variably overlying and intruding the gneissic crystalline basement. Supracrustal belts located outside the basin margins are interpreted to continue below the basin fill. Major structures have been delineated geophysically including the Howard Lake Shear Zone and the Bathurst and McDonald fault systems. Northwest-trending structures forming part of the Bathurst fault system appear to control the unconformity surface morphology and the location of basin depocenters. The geologic interpretations are corroborated by joint gravity and magnetic modeling of profiles that reveal the deepest part of the Thelon Basin reaches depths of [Formula: see text] in an area of subdued magnetic and gravimetric response to the north. The basin is a focus of active exploration for uranium, and we have found that areas along the south and eastern margins underlain by U-rich granitoid rocks may have significant potential where intersected by reactivated faults.
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Gaber, Gaber M., Salah Saleh, and Mostafa Toni. "Crustal thickness and structural pattern evaluation of Sinai Peninsula using three-dimensional density modeling with aeromagnetic and earthquake data." Acta Geophysica 70, no. 2 (March 10, 2022): 639–57. http://dx.doi.org/10.1007/s11600-022-00744-4.
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AbstractThe Sinai Peninsula is a subplate located between the African and Arabian plates. It is an important subplate in the world; however, this region is poorly understood because of the shortage of geophysical data. Thus, this study focuses on built a three-dimensional (3D) high-resolution forward model of the crustal thickness with a new tectonic model and structural evaluation of the Sinai Peninsula to understand this area tectonically and determine its lithospheric and crustal thicknesses. Qualitative and quantitative interpretations of Bouguer gravity, reduced-to-the-pole (RTP) aeromagnetic, and earthquake data are explained to achieve the goals of this study. Two-dimensional (2D) interactive sequential modeling of gravity data is performed along with some well-selected profiles with existing crustal layer depth points from previous works in the studied region. Seventeen 2D models are constructed and used to determine the basement, Conrad (lower crust boundary), and Moho (upper mantle boundary) depths and to build a 3D model. Accuracy of the 3D built model is evaluated by extracting observed, calculated, and residual gravity anomaly maps. The results show that the basement rocks appear on the surface in the South of Sinai and deepen (down to 4.5 km) toward the North. The Conrad surface varies approximately from 16 km (in the northeast and southwest of Sinai) to 22.8 km (in the southeast). The Moho surface depth (i.e., crustal thickness) varies approximately from 28.8 to 34.2 km, and it deepens toward the northeastern and southwestern parts of Sinai. A tentative basement structure map is constructed from the horizontal gradient (H-gradient) filter and the 3D Euler deconvolution of the Bouguer gravity and RTP aeromagnetic data. Correlation between the geological background of the study area and the obtained results suggests that the Sinai Peninsula is tectonically active, mainly in its southern portion due to the tectonic movements along the Gulf of Suez and the Gulf of Aqaba. The crustal thickness increases southward and thins northward.
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Abbassi, Bahman, Li-Zhen Cheng, Michel Jébrak, and Daniel Lemire. "3D Geophysical Predictive Modeling by Spectral Feature Subset Selection in Mineral Exploration." Minerals 12, no. 10 (October 14, 2022): 1296. http://dx.doi.org/10.3390/min12101296.
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Several technical challenges are related to data collection, inverse modeling, model fusion, and integrated interpretations in the exploration of geophysics. A fundamental problem in integrated geophysical interpretation is the proper geological understanding of multiple inverted physical property images. Tackling this problem requires high-dimensional techniques for extracting geological information from modeled physical property images. In this study, we developed a 3D statistical tool to extract geological features from inverted physical property models based on a synergy between independent component analysis and continuous wavelet transform. An automated interpretation of multiple 3D geophysical images is also presented through a hybrid spectral feature subset selection (SFSS) algorithm based on a generalized supervised neural network algorithm to rebuild limited geological targets from 3D geophysical images. Our self-proposed algorithm is tested on an Au/Ag epithermal system in British Columbia (Canada), where layered volcano-sedimentary sequences, particularly felsic volcanic rocks, are associated with mineralization. Geophysical images of the epithermal system were obtained from 3D cooperative inversion of aeromagnetic, direct current resistivity, and induced polarization data sets. The recovered cooperative susceptibilities allowed locating a magnetite destructive zone associated with porphyritic intrusions and felsic volcanoes (Au host rocks). The practical implementation of the SFSS algorithm in the study area shows that the proposed spectral learning scheme can efficiently learn the lithotypes and Au grade patterns and makes predictions based on 3D physical property inputs. The SFSS also minimizes the number of extracted spectral features and tries to pick the best representative features for each target learning case. This approach allows interpreters to understand the relevant and irrelevant spectral features in addition to the 3D predictive models. Compared to conventional 3D interpolation methods, the 3D lithology and Au grade models recovered with SFSS add predictive value to the geological understanding of the deposit in places without access to prior geological and borehole information.
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Le Maire, Pauline, Isabelle Thinon, Julie Tugend, Benoît Issautier, Guillaume Martelet, Fabien Paquet, Jean-Noël Proust, Thierry Nalpas, Aurélie Peyrefitte, and Albane Canva. "New Magnetic compilation and interpretation of the Bay of Biscay and surrounding continental shelves." BSGF - Earth Sciences Bulletin 192 (2021): 58. http://dx.doi.org/10.1051/bsgf/2021048.
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Producing accurate structural maps is a pre-requisite to unravel the tectonic evolution of a region. For this purpose, magnetic anomaly maps are helpful data sets for the identification and mapping of geological features. We compiled 154 marine surveys and 7 aeromagnetic campaigns covering the Bay of Biscay, its surrounding continental shelves and western part of the Pyrenees. As the initial data sets had heterogeneous acquisition parameters, we applied a series of transforms before merging the data. We performed a variable reduction to the pole to localize the extrema of the anomaly vertically to their causative sources and facilitate geological interpretations. The resulting intermediate resolution maps compiled at 500 m altitude offshore and 3000 m both on- and offshore, display magnetic trends and patterns. They are enhanced by several potential field operators (analytic signal, tilt angle, vertical derivative) enabling the interpretation of the geometry of the sources causing the anomaly (3D, 2D and 2.5D). The analysis of these magnetic maps allows us to precise the distribution and segmentation of crustal domains previously identified in the Bay of Biscay and its adjacent continental shelves. A series of crustal scale structures mapped onshore and formed during and after the Variscan orogeny show well on this new map compilation, allowing the continuous onshore-offshore mapping of some of them and revealing their role in segmenting the northern margin of the Bay of Biscay. This new compilation notably reveals variations in the magnetic signature of the Ocean-Continent-Transition (OCT) that we interpret as related to an increased magmatic production of the eastern part of the Bay of Biscay OCT during continental breakup. In addition to precise previous structural maps, this new magnetic compilation opens new perspectives for the interpretation of the Bay of Biscay geodynamic setting.
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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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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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Boerner, D. E., R. D. Kurtz, J. A. Craven, G. M. Ross, and F. W. Jones. "A synthesis of electromagnetic studies in the Lithoprobe Alberta Basement Transect: constraints on Paleoproterozoic indentation tectonics." Canadian Journal of Earth Sciences 37, no. 11 (November 1, 2000): 1509–34. http://dx.doi.org/10.1139/e00-063.
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Electromagnetic surveys of the crust and upper mantle underlying the Western Canada Sedimentary Basin have revealed two conductivity anomalies that are arguably related to Paleoproterozoic tectonic processes, recording a signature diagnostic of euxinic (foreland?) basin succession and perhaps defining a deep-marine transtensional basin. As well, a regionally pervasive electrical anisotropy throughout the crust crosses Proterozoic tectonic boundaries and is aligned in many areas with the regional tectonic fabric (as expressed by aeromagnetic data) created during the final stages of Proterozoic tectonic assembly of western Laurentia. There is also an order of magnitude increase in the upper mantle conductivity underlying Churchill Province Archean crust relative to that underlying the neighbouring Proterozoic crust. The interpretations of the electromagnetic observations are analogous with the Tertiary to modern-day tectonic development of southeast Asia. The foreland basin succession would reflect the closing of the South China Sea and the deep-marine basin may be analogous to the Andaman Sea and North Sumatra basin. Electrical anisotropy may be indicative of the successive lateral accretion of oceanic crust beneath the continental shelf followed by shortening. The enhanced mantle conductivity mechanism is unknown, although it may be associated with metasomatic modification of the subcontinental lithosphere subsequent to collisional thickening and followed by delamination or convective removal of some lithosphere. While the Indo-EurasianLaurentia tectonic analogy is incomplete, it is sufficiently compelling in explaining the electromagnetic and other data that it is a useful basis for understanding the Proterozoic assembly of Laurentia.
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Bongiolo, Alessandra De Barros e. Silva, Francisco José Fonseca Ferreira, André Virmond Lima Bittencourt, and Eduardo Salamuni. "CONNECTIVITY AND MAGNETIC-STRUCTURAL COMPARTMENTALIZATION OF THE SERRA GERAL AND GUARANI AQUIFER SYSTEMS IN CENTRAL STATE OF PARANÁ (PARANÁ BASIN, BRAZIL)." Revista Brasileira de Geofísica 32, no. 1 (March 1, 2014): 141. http://dx.doi.org/10.22564/rbgf.v32i1.402.
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ABSTRACT. Recent research projects on the Guarani Aquifer System (GAS-granular), Paraná Basin, Brazil, have been evaluating the tectonic control and its hydrogeological potential, flow patterns, chemical properties and environmental protection aspects.One of this projects is the present research that has investigated a structured area in central State of Paraná of about 23,000 km2, delimited by coordinates 24◦00’S and 25◦00’S, 51◦00’W and 53◦00’W. The study involves Geographic Information System (GIS) integration of aeromagnetic, geological and structural characterization of lineaments based on Digital Elevation Model (DEM) and Landsat images, hydrogeological and hydrochemical data. Basaltic flows and diabase dikes (NW-SE) of the Serra Geral Formation (Lower Cretaceous) predominate in the studied area. These rocks correspond to the overlying Serra Geral Aquifer System (SGAS-fractured). The purpose of the study is to investigate the structural control on both flow and chemism of SGAS groundwater and also to identify fractures that might represent hydraulic connectivity zones to the underlying GAS. Processing and interpretation of aeromagnetic data using various techniques, useful for enhancing shallow sources, and integration with further remote sensing and geological data, allowed to outline the regional structural framework, which is characterized by a mosaic of tectonic blocks delimited by NW-SE (diabase dykes) and NE-SW (Paraná Basin basement) structures. This magnetic-structural framework was compared with the spatial distribution of hydrogeological and hydrochemical parameters. The integrated interpretations made it possible to recognize the structural control on hydrogeology and hydrochemistry of the SGAS and SAG. The results, presented in a georeferenced map, show the main zones of confinement and/or connection of SGAS and GAS. Keywords: Guarani Aquifer System, Serra Geral Aquifer System, Paran´a Basin, hydraulic connection, aeromagnetometry. RESUMO. Projetos recentes de pesquisa no Sistema Aquífero Guarani (SAG-granular), Bacia do Paraná, Brasil, têm avaliado o controle tectônico e seu potencial hidrogeológico, padrões de fluxo, propriedades químicas e aspectos de proteção ambiental. Um destes projetos é a presente pesquisa, a qual investigou uma área estruturada na região central do Estado do Paraná, delimitada pelas coordenadas 24◦00’S e 25◦00’S, 51◦00’W e 53◦00’W, com aproximadamente 23.000 km2. O estudo envolve integrações em Sistema de Informações Geográficas (SIG) de dados aeromagnéticos, geológicos, estruturais Modelo Digital de Elevação (MDE) e imagens Landsat, hidrogeológicos e hidroquímicos. Lavas basálticas e diques de diabásio (NW-SE) da Formação Serra Geral (Cretáceo Inferior) predominam na área estudada. Estas rochas correspondem ao Sistema Aquífero Serra Geral (SASG-fraturado), sobrejacente. O objetivo do estudo ´e investigar o controle estrutural do fluxo e do quimismo das águas subterrâneas do SASG e identificar também fraturas que possam representar zonas de conexão hidráulica com o SAG subjacente. Processamentos e interpretações de dados aeromagnéticos, a partir de várias técnicas, e a integração com dados de outros sensores remotos e geológicos permitiram a composição de um arcabouço estrutural regional, o qual é caracterizado por um mosaico de blocos tectônicos limitados por estruturas NW-SE (diques de diabásio) e NE-SW (embasamento da Bacia do Paraná). Este novo arcabouço magnético-estrutural foi comparado com a distribuição espacial dos parâmetros hidrogeológicos e hidroquímicos. A interpretação integrada permitiu reconhecer o controle estrutural da hidrogeologia/hidroquímica dos SASG e SAG. Os resultados, apresentados em um mapa georreferenciado, mostram as principais zonas de confinamento e/ou conexão dos SASG e SAG. Palavras-chave: Sistema Aquífero Guarani, Sistema Aquífero Serra Geral, Bacia do Paraná, conexão hidráulica, aeromagnetometria.
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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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de Castro, David Lopes, Francisco Hilário Bezerra, Reinhardt Adolfo Fuck, and Roberta Mary Vidotti. "Geophysical evidence of pre-sag rifting and post-rifting fault reactivation in the Parnaíba basin, Brazil." Solid Earth 7, no. 2 (April 11, 2016): 529–48. http://dx.doi.org/10.5194/se-7-529-2016.
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Abstract. This study investigated the rifting mechanism that preceded the prolonged subsidence of the Paleozoic Parnaíba basin in Brazil and shed light on the tectonic evolution of this large cratonic basin in the South American platform. From the analysis of aeromagnetic, aerogravity, seismic reflection and borehole data, we concluded the following: (1) large pseudo-gravity and gravity lows mimic graben structures but are associated with linear supracrustal strips in the basement. (2) Seismic data indicate that 120–200 km wide and up to 300 km long rift zones occur in other parts of the basins. These rift zones mark the early stage of the 3.5 km thick sag basin. (3) The rifting phase occurred in the early Paleozoic and had a subsidence rate of 47 m Myr−1. (4) This rifting phase was followed by a long period of sag basin subsidence at a rate of 9.5 m Myr−1 between the Silurian and the late Cretaceous, during which rift faults propagated and influenced deposition. These data interpretations support the following succession of events: (1) after the Brasiliano orogeny (740–580 Ma), brittle reactivation of ductile basement shear zones led to normal and dextral oblique-slip faulting concentrated along the Transbrasiliano Lineament, a continental-scale shear zone that marks the boundary between basement crustal blocks. (2) The post-orogenic tectonic brittle reactivation of the ductile basement shear zones led to normal faulting associated with dextral oblique-slip crustal extension. In the west, pure-shear extension induced the formation of rift zones that crosscut metamorphic foliations and shear zones within the Parnaíba block. (3) The rift faults experienced multiple reactivation phases. (4) Similar processes may have occurred in coeval basins in the Laurentia and Central African blocks of Gondwana.
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Manson, Matthew L., and Henry C. Halls. "Proterozoic reactivation of the southern Superior Province and its role in the evolution of the Midcontinent rift." Canadian Journal of Earth Sciences 34, no. 4 (April 1, 1997): 562–75. http://dx.doi.org/10.1139/e17-045.
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Major reverse faults associated with the late compressional phase of the 1.1 Ga Midcontinent rift in the western Lake Superior region appear to cut across the rift at the eastern end of the lake and join with reverse faults on the eastern shoreline, defined on the basis of geological and potential field data. The continuation of the faults across eastern Lake Superior is inferred on evidence drawn from nearshore shipborne magnetic surveys together with new interpretations of published bathymetric and GLIMPCE aeromagnetic data. In the Archean Superior Province about 100 km east of Lake Superior, paleomagnetic and petrographic data from the 2.45 Ga Matachewan dyke swarm show that the Kapuskasing Zone, a narrow belt of uplifted crust, can be extended to within 50 km of the Lake Superior shoreline and has bounding reverse faults that are almost continuous with two faults of similar dip and sense of displacement that define the inversion of the Midcontinent rift in the central and western parts of the lake. Since the Kapuskasing Zone is dominantly a Paleoproterozoic (about 1.9 Ga) structure, the continuity suggests that the Lake Superior faults, whose last major activity was during the Grenville Orogen, may represent reactivation of much older faults that were part of an extended Kapuskasing structure. Within the Superior Province to the north and east of Lake Superior, published radiometric data on biotites suggest a series of alternating crustal blocks of varying tectonic stability, separated by northeast-trending faults. The Lake Superior segment of the Midcontinent rift developed within the most unstable block, bounded by the Gravel River fault to the northwest and the Ivanhoe Lake fault (the eastern margin of the Kapuskasing Zone) to the southeast.
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Tschirhart, Peter, and Bill Morris. "Analysis of petrophysical properties of rocks from the Bathurst Mining Camp: Constraints on gravity and magnetic modeling." Interpretation 2, no. 4 (November 1, 2014): SJ133—SJ150. http://dx.doi.org/10.1190/int-2014-0107.1.
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Understanding the physical rock properties of different lithologies within a mining district allows one to link geologic observations with geophysical interpretations. This paper presents a physical rock property database for the Bathurst Mining Camp (BMC). Density–magnetic susceptibility bivariate plots are used to illustrate patterns indicative of changes in the concentration of paramagnetic versus ferrimagnetic mineral phases. Q-Q plots and histograms are used to determine if a lithology is characterized by a unimodal or multimodal physical property population. To use the physical property data in geophysical models, the rock classification was reduced to five lithological groups and three subgroups. The results of two geophysical modeling exercises, using lithological and petrophysical data as input constraints, are presented. Late-stage deformation of the BMC resulted in two large-scale plunging folds: the Nine Mile Synform (NMS) and the Tetagouche Antiform. The subsurface geometry of the NMS along the model profile was initially estimated from surficial geology maps projected down the plunge of the fold axis. Geophysical data requires dense and magnetic volcanics on the east limb of the Nine Mile Syncline to be nearer to the surface than previously expected. The magnetic anomaly associated with the Armstrong B mineral deposit was modeled using constrained discrete object source geometry. To achieve a satisfactory match between the observed and calculated data requires a significant component of magnetic remanence. The orientation of the calculated remanence vector is similar to a paleomagnetically determined in situ direction and to the direction estimated for Laurentia during the Paleozoic. The source body estimated by the inversion is significantly larger than the known thickness of the ore zone. This is a consequence of computing the inversion on a gridded aeromagnetic data set, which has a cell size that is larger than the known thickness of the ore body.
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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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Hendrickson, Michael D. "Regional and local controls on Archean rock-hosted cobalt mineralization at the McAra deposit, southern Superior Province, Ontario, Canada." Canadian Journal of Earth Sciences 57, no. 12 (December 2020): 1447–62. http://dx.doi.org/10.1139/cjes-2020-0059.
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The McAra deposit is in eastern Ontario, Canada, and is hosted in an Archean inlier to the Paleoproterozoic Huronian basin. It is currently estimated to contain ∼2.4 million pounds of cobalt at an average grade of 1.25%. New drill data show the mineralized zone comprises glaucodot–cobaltite veins and breccias that transect a mafic–siliciclastic volcanogenic massive sulfide (VMS) deposit. The high cobalt grade and host stratigraphy at the McAra deposit contrast with five-element (Ag–Co–Ni–Bi–As) deposits at the Cobalt and Gowganda camps in the region that produced high-grade silver and by-product cobalt from veins spatially associated with Nipissing Gabbro intrusions. However, geochemical data from recent core samples alongside fluid inclusion and mineralogical data suggest the cobalt zone at McAra and the five-element veins share a similar metal assemblage and were deposited from similar fluids. The mafic–siliciclastic VMS deposit at McAra contains anomalous amounts of cobalt, suggesting the Archean host stratigraphy was the source for the high-grade cobalt zone. Basin brines in the Paleoproterozoic are interpreted to have leached cobalt from Archean rocks and then redeposited it through oxidation–reduction reactions along synvolcanic faults that controlled earlier VMS deposit formation. High-resolution aeromagnetic data show that McAra is immediately adjacent to a mafic dike that transects the Huronian basin along a northwest-striking, crustal-scale fault system. These data, alongside observations from field mapping, also suggest the deposit is on the margin of a sub-basin that contains an 80 km2 Nipissing sill that may have originally overlain the deposit area and been a hydrologic seal during mineralization. The new deposit- and regional-scale data and interpretations are used to create a model for the McAra deposit and provide evidence for why it is cobalt-rich relative to other five-element veins. The model and data can be used to guide exploration for additional cobalt-rich deposits in the region and similar settings globally.
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Ayigun, Sunday, K. Y. Hamid, and Omoniyi O. Titilola. "Review: Spectral Analysis of Aeromagnetic Data Interpretation." International Research Journal of Pure and Applied Physics 9, no. 1 (January 15, 2022): 1–11. http://dx.doi.org/10.37745/irjpap.13/vol9n1111.
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Spectral analysis of aeromagnetic data interpretation method is a vital tool in the field of geology and geophysics for solid minerals, groundwater, hydrocarbon and geothermal energy exploration. Human existence depends on availability of mineral and their explorations for daily activities in every part of the world. In order to reduce the scarcity of minerals and problems associated with minerals exploration, this paper reviews shed more light on source of data acquisition, data processing and interpretation in respect to the subject matter. Two case studies were considered, the first case study was on the spectral analysis method of aeromagnetic data interpretation in Longuda Plateau and its environs in Adamawa state North Eastern Nigeria. The data of the study area was divided into 16 x16 data points; the data was subjected to 2D Fourier transformation. After the spectral analysis the depth to magnetic sources were discovered ranging from 1900 m to 2620 m at the basement and shallow depth was ranging from 512 m to 670 m magnetic sources. The second case study was on magnetic data processing for hydrocarbon exploration in the Pannonian Basin, Yogoslavia, from the magnetic data analysis, hydrocarbon potential zones were identified.
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Cao, Wei, Hao Qing, Xing Xu, Chang Liu, Silin Chen, Yi Zhong, Jiabo Liu, et al. "Pre-Archaeological Investigation by Integrating Unmanned Aerial Vehicle Aeromagnetic Surveys and Soil Analyses." Drones 6, no. 9 (September 6, 2022): 243. http://dx.doi.org/10.3390/drones6090243.
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Magnetic surveys have been widely used in archaeological field investigations. However, conventional survey methods are often restricted by complicated field conditions and ambiguities in data interpretation. In this study, a novel magnetic survey system was designed for pre-archaeological investigation (preliminary survey prior to the archaeological excavation) based on a modified quadrotor unmanned aerial vehicle (UAV) and was successfully applied to an archaeological area with a complex landform in Huizhou, China. Results show that the target anomaly identified by UAV aeromagnetic survey corresponds well to the location of a potential archaeological site. Subsequent soil analyses further confirm the archaeological value of UAV aeromagnetic results and provide strong constraints on the interpretation of target anomalies. This study demonstrates that the newly proposed UAV aeromagnetic system can adapt to the various field conditions with the advantages of flexibility and efficiency, which has great potential for future archaeological investigations.
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A. EI-Khafeef, Ahmed, and Shokry A. Soliman. "Interpretation of aeromagnetic data in West Qattara Depression, Western Desert Egypt by using up to date transformation techniques." International Journal of Academic Research 5, no. 5 (October 15, 2013): 193–201. http://dx.doi.org/10.7813/2075-4124.2013/5-5/a.28.
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Prieto, Corine, Carolyn Perkins, and Ernest Berkman. "Columbia River Basalt Plateau—An integrated approach to interpretation of basalt‐covered areas." GEOPHYSICS 50, no. 12 (December 1985): 2709–19. http://dx.doi.org/10.1190/1.1441891.
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An interpretation is presented of a 219 km regional profile which traverses the eastern Columbia River Plateau in Washington State. Aeromagnetic, magnetotelluric (MT), and gravity data were first interpreted separately. All three data sets then were satisfied by a single geologic model. The objective of this case study is to illustrate the individual contributions derived from these three geophysical data sets to a final integrated interpretation. The aeromagnetic interpretation has produced regional structural information and data from which rock compositions can be inferred. The MT interpretation shows that the basalt/sediment interface can be determined, and thus a relative sediment thickness can be inferred. The gravity interpretation is dependent upon an additional method to determine either the basalt or basement horizon. In order for the gravity interpretation to approximate depth to basement or sedimentary thickness, the base of the basalt must be determined from another scientific method. From comparison of the regional structural results of the three geophysical techniques we conclude that aeromagnetic or MT data can be used to determine major structural trends. Reasonable rock compositions are also determined from the combined data sets. The interpreter must be aware of the different rock properties measured by each tool when performing an integrated interpretation; comparisons between the various techniques must be based upon similar assumptions. We recommend that detailed, integrated models be included for a thorough evaluation of any basalt‐covered area. The analysis of rock composition and regional structural information thus derived provides a sound basis for a regional tectonic interpretation and subsequent prospect evaluation.
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Cowan, D. R., and S. Cowan. "Analytical Techniques in Interpretation of Regional Aeromagnetic Data." Exploration Geophysics 22, no. 1 (March 1991): 81–84. http://dx.doi.org/10.1071/eg991081.
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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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Ndlovu., Thabisani, Mashingaidze R. T., and Mpofu P. "Analytic Signal and Euler Depth Interpretation of Magnetic Anomalies: Applicability to the Beatrice Greenstone Belt." Journal of Geography and Geology 7, no. 4 (December 2, 2015): 108. http://dx.doi.org/10.5539/jgg.v7n4p108.
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We apply the Analytic Signal and Euler depth filtering techniques on magnetic data to identify a magnetic causative body location-depth relationship, two parameters of importance in both geophysical exploration and ore body modelling. We identify a dipping magnetic contact from the interpreted Euler depth anomalies, showing a good agreement with both the Total Field Magnetic (TFM) map and the Analytic Signal (AS) map. The Euler depth anomalies correlate well with the locations and edges of shallow causative bodies. The deeper Euler interpreted sources explain the magnetic high on the regional aeromagnetic map which is coincident with neither geological contacts nor the more recent dolerite intrusions. This suggests that the magnetic highs on the regional aeromagnetic map are due to deep seated sources, otherwise invisible on the regional geological map. The results show the usefulness and relevancy of these two filters not only in interpreting routine TFM data from the study area, but up to a regional scale. While the aeromagnetic data shows that the magnetisation pattern is predominantly divorced from the geological map, the ground magnetic data interpretation points to a more recent magnetisation of the belt, enabling conclusions to be drawn about the geological history and structural geology otherwise not evident on the geological map.
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Cooper, G. R. J. "Reprocessing aeromagnetic data using modern semi-automatic interpretation methods." First Break 37, no. 8 (August 1, 2019): 103–6. http://dx.doi.org/10.3997/1365-2397.n0045.
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Holden, Eun-Jung, Michael C. Dentith, T. Campbell McCuaig, Tristan Chadwick, Tele Tan, and Geoff West. "Profiling of Aeromagnetic Data Interpretation using the Eye Tracker." ASEG Extended Abstracts 2010, no. 1 (December 2010): 1–4. http://dx.doi.org/10.1081/22020586.2010.12041959.
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Arkani-Hamed, J., and D. W. Strangway. "Interpretation of the aeromagnetic anomalies of southern Vancouver Island." Canadian Journal of Earth Sciences 25, no. 6 (June 1, 1988): 801–9. http://dx.doi.org/10.1139/e88-079.
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A low-pass filtered aeromagnetic map of southern Vancouver Island is inverted into a magnetization-contrast map that illustrates the lateral variations in the magnetization of the crust. The Island Intrusions and the West Coast Crystalline Complex are characterized by high magnetization relative to the other lithologic groups. The Island Intrusions form an almost continuous pluton in the deeper part of the crust. The low-magnetic Leech River Formation thickens northward. The almost uniform magnetic signature of the Leech River Formation in the east–west direction indicates that the crustal structure revealed from the Lithoprobe seismic results is typical throughout the formation west of the Survey Mountain fault. A low-magnetic zone, elongated in the northwest–southeast direction, cuts through the high-magnetic Metchosin basalts from the southern tip of the island to the Leech River fault. It coincides with the Sooke gabbros exposed in the southern tip of the island, implying that the gabbros probably cut the entire Metchosin basalts at depth.
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Socías, Isabel, Julio Mezcua, Jonh Lynam, and Recaredo Del Potro. "Interpretation of an aeromagnetic survey of the Spanish mainland." Earth and Planetary Science Letters 105, no. 1-3 (July 1991): 55–64. http://dx.doi.org/10.1016/0012-821x(91)90120-7.
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Asfirane, F., and A. Galdeano. "The aeromagnetic map of northern Algeria: Processing and interpretation." Earth and Planetary Science Letters 136, no. 1-2 (November 1995): 61–78. http://dx.doi.org/10.1016/0012-821x(95)00043-4.
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Ross, Howard P., Dennis L. Nielson, and Dale J. Green. "Aeromagnetic survey and interpretation, Ascention Island, South Atlantic Ocean." Geothermics 25, no. 4-5 (August 1996): 471–88. http://dx.doi.org/10.1016/0375-6505(96)00016-8.
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Zhang, Yong‐xia. "Aeromagnetic anomalies and perspective oil traps in China." GEOPHYSICS 59, no. 10 (October 1994): 1492–99. http://dx.doi.org/10.1190/1.1443539.
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Based on analyses of aeromagnetic data from known oil and gas fields in China, aeromagnetic anomalies have been classified according to their genesis into three types: (1) structure‐associated anomalies related to volcanic rock, (2) anomalies related to magnetic basement fault blocks, and (3) structure‐associated anomalies related to weakly magnetic sedimentary strata. The most successful applications of aeromagnetic data for locating favorable oil and gas structures are in the following kinds of areas: (1) areas where basement fault blocks of inhomogeneous lithology and magnetization are developed; (2) areas of weakly magnetic layered strata with a considerable thickness, either effusive or clastic deposits; and (3) areas where magnetic layers have undergone tectonic deformation with faulting and dip angles larger than 30 degrees. For reliable detection of such structures in sedimentary rocks and associated oil and gas traps, an integrated interpretation of geological and geophysical data is necessary.
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Pustisek, A. M. "Noniterative three‐dimensional inversion of magnetic data." GEOPHYSICS 55, no. 6 (June 1990): 782–85. http://dx.doi.org/10.1190/1.1442891.
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The interpretation of magnetic or aeromagnetic data often requires the inverse problem’s solution of the structure of the magnetization interface. This nonlinear inverse problem of mapping the basement topography from potential field data was first discussed by Peters (1949).
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Barbosa, Valéria C. F., João B. C. Silva, and Walter E. Medeiros. "Stability analysis and improvement of structural index estimation in Euler deconvolution." GEOPHYSICS 64, no. 1 (January 1999): 48–60. http://dx.doi.org/10.1190/1.1444529.
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Euler deconvolution has been widely used in automatic aeromagnetic interpretations because it requires no prior knowledge of the source magnetization direction and assumes no particular interpretation model, provided the structural index defining the anomaly falloff rate related to the nature of the magnetic source, is determined in advance. Estimating the correct structural index and electing optimum criteria for selecting candidate solutions are two fundamental requirements for a successful application of this method. We present a new criterion for determining the structural index. This criterion is based on the correlation between the total‐field anomaly and the estimates of an unknown base level. These estimates are obtained for each position of a moving data window along the observed profile and for several tentative values for the structural index. The tentative value for the structural index producing the smallest correlation is the best estimate of the correct structural index. We also propose a new criterion to select the best solutions from a set of previously computed candidate solutions, each one associated with a particular position of the moving data window. A current criterion is to select only those candidates producing a standard deviation for the vertical position of the source smaller than a threshold value. We propose that in addition to this criterion, only those candidates producing the best fit to the known quantities (combinations of anomaly and its gradients) be selected. The proposed modifications to Euler deconvolution can be implemented easily in an automated algorithm for locating the source position. The above results are grounded on a theoretical uniqueness and stability analysis, also presented in this paper, for the joint estimation of the source position, the base level, and the structural index in Euler deconvolution. This analysis also reveals that the vertical position and the structural index of the source cannot be estimated simultaneously because they are linearly dependent; the horizontal position and the structural index, on the other hand, are linearly independent. For a known structural index, estimates of both horizontal and vertical positions are unique and stable regardless of the value of the structural index. If this value is not too small, estimates of the base level for the total field are stable as well. The proposed modifications to Euler deconvolution were tested both on synthetic and real magnetic data. In the case of synthetic data, the proposed criterion always detected the correct structural index and good estimates of the source position were obtained, suggesting the present theoretical analysis may lead to a substantial enhancement in practical applications of Euler deconvolution. In the case of practical data (vertical component anomaly over an iron deposit in the Kursk district, Russia), the estimated structural index (corresponding to a vertical prism) was in accordance with the known geology of the deposit, and the estimates of the depth and horizontal position of the source compared favorably with results reported in the literature.
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Batista, Jose Alberto. "Interpretation of aeromagnetic data using GIS to evaluate the geotectonic regime of the Sabinas Basin." Earth Sciences Research Journal 21, no. 4 (October 1, 2017): 175–81. http://dx.doi.org/10.15446/esrj.v21n4.57924.
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The study present the use of Geographic Information System (GIS) to assess the geotectonic regimen of the Sabinas Basin. Initially, the GIS database was designed using geological and geophysical information (total magnetic field reduced to the pole). Subsequently, 2D models of the basin were obtained along 4 profiles running on a north-south direction. The implementation of GIS enables a geological-geophysical interpretation generating various thematic maps that overlap the magnetic map during interpretation. The analysis of overlapping maps enables the identification of areas with different geotectonic regimes in the Sabinas Basin, as well as the relationship between these environments and mineralization. The qualitative and quantitative interpretation of the aeromagnetic data obtained for the total magnetic field reduced to the pole delineate uplifted basement areas as well as shallower blocks within them. This paper presents the location of both the basin´s deepest zones and its probable faults, which can be linked to the block boundaries. The faults zones and block boundaries correspond to the main mineral deposits found in the basin. Finally, the geotectonic regime of some sectors of the basin is detailed in order to reaffirm the results obtained by the interpretation of aeromagnetic data.
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Feininger, Tomas, and Ingo Ermanovics. "Geophysical interpretation of the Torngat orogen along the North River – Nutak transect, Labrador." Canadian Journal of Earth Sciences 31, no. 4 (April 1, 1994): 722–27. http://dx.doi.org/10.1139/e94-064.
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A 19.3 mGal (1 Gal = 1 cm/s2) positive Bouguer gravity anomaly and a broad aeromagnetic low coincide with the Tasiuyak domain of the early paleo-Proterozoic Torngat orogen. The domain evolved during the collision of the western margin of the Archean Nain Province with an inferred, eastward-facing, platform-to-rise, sedimentary wedge sited on a proto-continent of Churchill (Rae) Province.A density contrast of +0.065 g∙cm−3 was measured between rocks of the Tasiuyak domain and those of the flanking Lac Lomier complex of the orogen and Nain Province. Using this contrast, a two and one-half dimensional model shows that rocks of Tasiuyak domain constitute a triangular prismatic body with maximum thickness of 13 km adjacent to Nain Province, which thins westward to a feather edge. The model is compatible, qualitatively, with the aeromagnetic anomaly and consonant with geological interpretation of an eastward-facing and thickening continental slope deposit. Deep exhumation of the Torngat orogen may account for the absence of paired gravity anomalies characteristic of many sutures elsewhere in the Canadian Shield.
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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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Ma, M., K. Yang, G. A. Feng, C. H. Wang, X. Li, and Q. Gao. "Aeromagnetic noise reduction and interpretation by Multifractal Singular Value Decomposition." IOP Conference Series: Earth and Environmental Science 289 (June 25, 2019): 012004. http://dx.doi.org/10.1088/1755-1315/289/1/012004.
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Henkel, Herbert. "The North Calotte project — Report on the aeromagnetic interpretation map." Geoexploration 23, no. 3 (September 1985): 433–34. http://dx.doi.org/10.1016/0016-7142(85)90039-0.
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