Contribution of applied geophysics in mining prospecting

Arabian Journal of Geosciences, 2011

From a geologist's perspective, magnetic data are most useful in mapping contacts and providing insight into the 3D geometry of the geology. Since the early 1970s, automatic methods based on the horizontal and vertical derivatives are applied to potential field data in order to map geological lineaments. In this paper, three methods for locating magnetic contacts are applied to magnetic anomaly data of the study area. The local maxima of horizontal gradient determined on the magnetic map and its upward continued maps to several heights delineate the contacts and indicate their dips. The amplitude of the 3D analytic signal of magnetic data provides information on the location of the edge of the sources in both the horizontal and vertical dimensions. The Euler deconvolution is also used to estimate the source depth at the contact location. These results allow the production of a structural map showing the magnetic lineaments for the survey area. This map is consistent with many faults already recognised or supposed by the traditional structural studies and highlights new ones by specifying their layout and dips.

Arabian Journal of Geosciences, 2017

The observed aeromagnetic anomaly map of Southern High Plateaus provides general information about the magnetization variations that are associated with subsurface magnetic sources, but it does not bring clear information about all geological elements of the study area. In this work, we attempt, by analyzing these aeromagnetic data, to determine structures of Paleozoic basement that may indicate the presence of major deep-seated structures in this area. To better understand and outline the basement geological structures, two approaches have been performed. Such analysis includes application of a low-pass filtering and spectral analysis, which permits an enhanced visual interpretation of the magnetization sources and leads to a better knowledge of the geological structures especially basins or intrusive bodies. The results obtained show magnetic anomalies indicating geological features trending NE-SW. They also reveal two depths of magnetic sources in the area. The deeper sources range from 1074 to 4057 m and reflect the Paleozoic basement. However, the shallower sources range from 153 and 596 m reflecting magnetic sources shallower than the basement. The outcomes of this study suggest a new structure and will contribute to better understand the characteristics and organization of the basin as well as the improvement of the geological map of the area for hydrocarbon exploration.

Central European Geology, 2013

The aim of this work is to interpret the geologic structures of the Agourai area (Paleozoic and Mesozoic structures) from processed magnetic maps. The detected magnetic anomalies from different standard methods used in aeromagnetism (Residual map, RTP map, horizontal gradient map) were compared to geologic structures and permit enhancing the mapping quality of some areas, and thus defining many geologic features. Existing geologic maps and geologic field studies allow interpreting some detected anomalies. It was thus possible to define the limits between the Paleozoic basement and the Mesozoic cover, to determine magnetic anomalies according to NE-SW trends compatible with the regional geologic structures and finally to detect a NE to SW-oriented fault system in the Mesozoic cover of the Agourai Plateau. Despite the reliability of this approach, some folded basaltic sills occurring in this region were not well detected, probably because of their reduced thickness.

Proceedings of The 2nd International Electronic Conference on Mineral Science, 2021

The NorthEastern of Morocco was widely known for its mining potential, so discovering new structural guidelines was indispensable to find out new mineralization. Indeed, applying airborne magnetic techniques proves its efficiency in underlining new tectonic accidents and highlighting magnetic sources mostly hidden by Quaternary sedimentary covers. A magnetic anomaly map was established to attain this goal, basing on powerful operators (reduction to the pole, upward continuation, and Euler deconvolution), made on airborne data surveys of the study area. The elaborated map shows: (1) zones of strong magnetizations related to the Tertiary and Quaternary volcanic lavas partly outcropping in the Oujda and Saka regions to the iron and manganese mineralization concentrated in the Triassic beds. (2) Zones of relatively low magnetic response came from basaltic cones filled in a small graben at Oujda region. (3) Zones of low magnetization corresponded to the Quaternary and Tertiary cover or the Triassic-Jurassic deposits. We have established a magnetic lineaments map that emphasized deep faults, two main trends have been identified: NE-SW with ENE-WSW and E-W, they are considered as a major's accidents because their depth reach to 2 km, as much as they inherited from the Hercynian and Alpine tectonics.

Bull of Ain Shams University, 1997

A new detailed geomagnetic survey for the area of Ras Garib for the total geomagnetic field were performed using two Proton magnetometers, one of them as a local reading inserted in the area, while the second was used for measuring the total intensity in which like configuration every about 250 meters. The area selected for the present study lies in between latitudes 28* 18* & 28* 28* N and Longitudes 32* 51* & 33 01* E. The study of the structural features indicates that there are four predominant sets of faults. These sets are trending N 35* E, N 45* W, N 75* E and N 75* W. Quantitative analysis on the major anomaly occupying the area revealed that the average depth to the top of the basement complex about 2.3 Km's. We conclude that the subsurface geologyic conditions are generally connected with these anomalies and show good accardanc.

This study presents original results regarding the use of aeromagnetic to explore deep subsurface structuring in southern part of Tunisian Sahel petroleum province (Eastern Tunisia, North Africa). Several filters and techniques were applied to the total magnetic intensity (TMI) grid. First, an adequate reduce to the pole (RTP) grid was generated. The RTP map shows 17 positive and negative anomalies associated with short-and long-wavelength amplitude anomalies. Positive anomalies correspond to high magnetic basement structures estimated from seismic lines in the area. Circular anomalies are also distinguished locally and can be explained by Cretaceous magmatic rocks recognized in numerous petroleum wells. Second, specific qualitative and quantitative filters (e.g., residual-regional separation, horizontal tilt angle (TDX), tilt angle (TILT), total horizontal derivative of tilt angle (THDTILT)) were applied to elucidate the form and the extent of buried magnetic anomalies and lineaments. The resulting deep structural map revealed the presence of NW-SE, N-S, and E-W regional magnetic basement structures and lineaments and a regional tectonic node surrounding Henchir Keskes-Agareb-Mahres-Hachichina area. Two magnetic inversion models calculated across the study area highlight west to east crustal thinning trend and permit depth to basement estimation. These results are valuable for future conventional and unconventional petroleum exploration in this underexplored southern part of Sahel plain.

In the present work, we present a reconnaissance study to elucidate and delineate the subsurface structures and tectonics of the area between Dahshour and El Fayoum province using available magnetic data; including land magnetic survey and aeromagnetic data. The study area has been selected due to its active tectonic situation. The magnetic data have been analyzed to provide new information about the tectonic setting and subsurface structures of the study area. A detailed land magnetic survey has been carried out for the total component of geomagnetic field using two Proton magnetometers, one of them as a local reading base station placed in the middle part of the area, while the second was used for measuring the total intensity of the different points in a mesh-like configuration. The necessary corrections for the measured magnetic data have been carried out. The total land intensity and aeromagnetic maps have been reduced to the north magnetic pole. Moreover, wave number filtering technique has been carried out on the magnetic data utilizing three types of filters with varying wavelengths. The application of these tools on magnetic data discriminated the variable sources of specific depth ranges for the residual and regional anomalies, as well as those limited to a certain depth interval. It was found that the main tectonic trends taken the directions NE-SW, NW-SE and E-W. Three basement cross-sections have been generated using the 2-D modeling to support the interpreted structures and give idea about the configuration of subsurface basement shape. Depth estimations have been conducted by application of the Power spectrum, analytical signal and 2-D modeling techniques. The results indicate that the average calculated depth ranges between 1.8 km to 3.5 km, while the depth to volcanic intrusions ranges between 0.20 km and 0.30 km.

Applied Sciences, 2022

Numerical analysis of geophysical data to uncover Precambrian belts and probably to enclose mineral deposits is becoming once more communal in mining activity. The method is founded on typifying zones branded to comprehend deposits and looking for analogous areas. The proposed work outlines a semi-automatic image processing system for the structural and mining investigation of the Bou Azzer inlier, which varies from preceding approaches as it is centered only on aeromagnetic data. The aeromagnetic signature of what seem to be geologically expressive features are pursued within the aeromagnetic items. Cobalt and associated mineralizations in the Bou Azzer inlier are recognized to arise nearby main crustal discontinuities revealing as significant shear zones, which turn act as drains for mineralizing fluids. Mineralization occurs in sectors of structural complexity beside the shear zones. Developing towards the semi-automatic uncovering of such regions, the furthermost prospective extents are those everywhere inferred structural complexity occurs next to the regions of magnetic discontinuity. The proposed method is mainly based on the approach developed by the center for exploration targeting. The study was led by means of aeromagnetic data from the Bou Azzer inlier, which is considered one of the most productive and prospective regions for minerals and base metal mineralization in Morocco. The combined results obtained from geological and geophysical data prove that prospective areas have a dominant trend of NNE-SSW, NW-SE, NNW-SSE, E-W, and NE-SW directions. The CET Grid and Porphyry Analyses show that the probable porphyry mineral deposit locations mainly concentrated in the center of inlier, the Foum Zguid dyke, and northern and eastern part, which correspond to the Bou Azzer ophiolitic complex and platform deposits of the Lower Neoproterozoic Tachdamt-Bleïda.

Research Square (Research Square), 2023

The Anti-Atlas fold and thrust belt is considered an important metallogenic province on the northern margin of the West African Craton (WAC). This structural domain is mainly controlled by structural features inherited from many orogeneses that underwent evolution from the Paleoproterozoic onward. Geophysical investigation is considered an effective tool for studying fracturing and establishing structural maps of sedimentary basins and inaccessible area. The Saghro massif of the Eastern Anti-Atlas is a large Precambrian inlier including the highest peak in the range, Jbel Mansour, reaching 2600 meters, along with many other inaccessible areas. In this work, we highlight the use of airborne magnetic data in the SouthEast part of the Saghro inlier to depict the tectonic framework and to establish the structural map of this part of the Pan African belt. We particularly focused on determining the local structures and tectonic units by applying many derivatives lters on the magnetic data reduced to pole. The superposition of all magnetic lineaments obtained from various edge detection techniques. The results outline directions that are the same as the general tectonic structures of the area. NE-SW and E-W directions corresponding mainly to Hercynian faults, while the NW-SE to ESE-WNW directions are related to the late Pan-African phase. The interpreted magnetic lineament maps identi ed new profound faults in this region, in addition to con rming other linear structures already highlighted by previous geophysical investigations. Our synthetic structural map of magnetic lineaments serves as a framework for future mining exploration.

Contributions to Geophysics and Geodesy

In the present work, we present a reconnaissance study to elucidate and delineate the subsurface structures and tectonics of the area between Dahshour and El Fayoum province using available magnetic data; including land magnetic survey and aeromagnetic data. The study area has been selected due to its active tectonic situation. The magnetic data have been analyzed to provide new information about the tectonic setting and subsurface structures of the study area. A detailed land magnetic survey has been carried out for the total component of geomagnetic field using two Proton magnetometers, one of them as a local reading base station placed in the middle part of the area, while the second was used for measuring the total intensity of the different points in a mesh-like configuration. The necessary corrections for the measured magnetic data have been carried out. The total land intensity and aeromagnetic maps have been reduced to the north magnetic pole. Moreover, wave number filtering technique has been carried out on the magnetic data utilizing three types of filters with varying wavelengths. The application of these tools on magnetic data discriminated the variable sources of specific depth ranges for the residual and regional anomalies, as well as those limited to a certain depth interval. It was found that the main tectonic trends taken the directions NE-SW, NW-SE and E-W. Three basement cross-sections have been generated using the 2-D modeling to support the interpreted structures and give idea about the configuration of subsurface basement shape. Depth estimations have been conducted by application of the Power spectrum, analytical signal and 2-D modeling techniques. The results indicate that the average calculated depth ranges between 1.8 km to 3.5 km, while the depth to volcanic intrusions ranges between 0.20 km and 0.30 km.