Geophysical Characterization of Subsurface Structures for Optimal Planning in the Abu Tartur Phosphate Mine

Geophysical Characterization of Subsurface Structures for Optimal Planning in the Abu Tartur Phosphate Mine | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Geophysical Characterization of Subsurface Structures for Optimal Planning in the Abu Tartur Phosphate Mine Gehad Ahmed, Mahmoud Senosy, Gamal Boghdady, Mosaad Ali This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6981993/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 21 Apr, 2026 Read the published version in Scientific Reports → Version 1 posted 13 You are reading this latest preprint version Abstract Optimal planning of Abu Tartur Mine (ATPM), in Egypt, requires comprehensive understanding of the region's phosphate ore geology. The recent closure of the subsurface ATPM was primarily due to insufficient geological data, including unrecognized faults that concealed phosphate beds. The present study is integrating gravity and magnetic geophysical methods to characterize the phosphate beds and identify geological structures. Aeromagnetic Reduced to Pole (RTP) and Bouguer anomaly data were used, with filters (analytical signal, first vertical derivative, high pass and low pass (applied to enhance interpretation. Through 2D gravity and magnetic modelling, the subsurface sedimentary sequence above the basement rocks was defined. The subsea depth to the subsurface rock layer boundaries were determined. Consequently, structure contour maps were created for the basement and the Nubian sandstone surfaces, along with Isopach map of the phosphatic rocks. Maps and filtered data revealed the predominant subsurface structures controlling the phosphate distribution. These structures are folds (plunging and double plunging synclines and anticlines with axes trending NE-SW, NNW-SSE, and NW-SE) and faults (normal and strike slip). Normal faults bound the ATPM plateau with downthrow directions outward. Phosphatic rocks thickness varies from 0.8 to 32 meter. The limited thickness is recorded in the present ATPM location, whereas the maximum thickness is observed at the troughs of the syncline folds located northeast and southwest of the plateau. Therefore, the ATPM location was suboptimal and uneconomical, while the northeast and southwest areas offer more promising targets for phosphate extraction. This misallocation likely contributed to mine failure. Earth and environmental sciences/Solid earth sciences/Geology Earth and environmental sciences/Solid earth sciences/Geophysics Abu Tartur Mine Aeromagnetic Bouguer gravity Subsurface structures Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 1. Introduction Optimal mine planning is essential for sustainable mining practices, as it mitigates the environmental and economic impacts of resource extraction 1 – 4 . Through advanced subsurface characterization and strategic operational design, mine planning minimizes costs and waste, reduces environmental damage, and extends the lifespan of mineral reserves 5 . This approach conserves resources and promotes the long-term viability of mining, aligning with sustainable development principles 6 , 7 . Phosphate ore, a non-renewable but essential resource for agriculture and industry, exemplifies this need 8 , 9 . As the primary component of phosphate fertilizers, it plays a vital role in global food production by enriching soil and increasing crop yields 10 , 11 Phosphate is also critical for animal feed, detergents, and various industrial chemicals 11 . Therefore, extracting and utilizing phosphate more efficiently is essential for addressing global food security while minimizing the environmental impact of mining 2 , 12 . As one of the world's significant phosphate reserves, the Abu Tartur Phosphate Mine (ATPM) in Egypt represents a vital resource for the nation's economic and industrial development 8 . However, the ATPM has faced significant operational challenges, culminating in the recent closure of its subsurface mining operations 13 . These challenges, primarily due to insufficient geological understanding and unrecognized subsurface structures, underscore the urgent need for improved methods for subsurface characterization to support effective mine planning and sustainable resource extraction 14 , 15 . The geological complexity of the ATPM region, characterized by concealed faults and variable thickness of phosphate layers, has historically hindered efficient mining operations 13 . Earlier efforts to map the subsurface geology relied on incomplete or imprecise datasets, leading to suboptimal placement of mining operations 16 . For example, the closure of the subsurface ATPM has been linked to an inadequate understanding of the fault systems and stratigraphic variations, which obscured the distribution of economically viable phosphate beds. This misallocation of mining resources not only increased operational costs but also contributed to the premature abandonment of potentially productive areas. Previous studies addressing the challenges of underground mine closures have predominantly focused on geotechnical aspects, such as optimizing extraction panel widths 17 , designing support systems 13 , and calculating suitable reinforcement strategies 16 . While these approaches provide valuable insights into the structural stability of underground mines, they often overlook the critical role of comprehensive geological assessments in addressing operational failures. At the ATPM, the decision to abandon underground mining in Favor of surface mining behind the plateau has left substantial phosphate reserves untapped, raising concerns about resource wastage and economic inefficiency. This highlights a significant gap in the literature: the lack of comprehensive geological analyses to identify and characterize subsurface structures that may offer viable solutions to sustain mining operations. Addressing this gap is essential to exploring alternative strategies that optimize resource utilization while ensuring economic and environmental sustainability. Geophysical methods have proven to be powerful tools for subsurface exploration, offering non-invasive means to delineate geological structures and characterize mineral deposits 18 – 21 . These techniques leverage the physical properties of rocks and their constituent minerals to investigate features of subsurface, playing a crucial role in mineral exploration by identifying and delineating the extent, boundaries, quantity, and quality of deposits before mining operations commence 22 – 24 . Among these methods, the magnetic technique is widely used due to its effectiveness in detecting and mapping subsurface anomalies 25 – 27 . For example, in Morocco's Aïn Beida mine, magnetic surveys successfully delineated manganese-rich zones associated with ferruginous minerals 28 , while in Ibadan, Nigeria, high resolution aeromagnetic data revealed potential mineral deposits using advanced processing techniques particularly, Derivative and Analytic Signal Amplitude 29 . Similarly, gravity methods have been employed in gold exploration in South Africa 30 , 31 and in the identification of chromite 32 , 33 , iron 34 , manganese 35 , copper sulphide ores 36 , 37 , and coal deposits 38 , 39 , further highlighting their versatility. While single geophysical methods have yielded significant insights, the complexity of ore-bearing formations often requires a multi-disciplinary approach 40 , 41 . Combining magnetic data with other geophysical methods, such as seismic and gravity techniques, enhances the understanding of underground geological structures and provides a more comprehensive view of potential zones of mineral accumulation. For instance, in Sefwi Belt of Ghana, integration of gravity and magnetic data were successfully delineated zones of gold mineralization, mapping lithological units and structural features with high precision 42 . Such integrations not only improve exploration accuracy but also reduce the risks and costs associated with drilling and direct exploration methods. Despite their proven success, the integration of Bouguer gravity and aeromagnetic data for systematic subsurface characterization had not been extensively studied in ATPM region. This lack of exploration leaves critical knowledge gaps regarding subsurface structures, limiting the potential for optimizing phosphate resource extraction. Addressing this gap through integrated geophysical techniques offers an opportunity to develop a more comprehensive understanding of the region’s geology, guiding future mining operations towards sustainability and economic feasibility. The present study aims to address these gaps by employing a comprehensive geophysical approach to characterize the subsurface structures of the ATPM region. Using Reduced to the Pole (RTP) aeromagnetic and Bouguer gravity anomaly data, along with advanced filtering techniques, this research identifies and models the key geological features controlling phosphate layer distribution. Structure contour maps and thickness maps generated from 2D modelling provide a detailed understanding of the subsurface environment, enabling the identification of optimal zones for future mining operations. This research contributes to the field by combining geophysical techniques to provide a holistic understanding of the ATPM region's geology. By pinpointing the structural controls on phosphate bed distribution, it highlights areas with higher economic potential and underscores the limitations of previous mine placement strategies. The results of this study not only have been helpful for ATPM but also offer a methodological framework for similar mining challenges worldwide, where subsurface geological complexities hinder resource extraction. 2. Location and Geological setting of the study area 2.1 Location of study area Phosphate deposits are distributed in several locations in Egypt along the phosphate belt. The investigated area is part of the Western Desert in Egypt, including the Abu Tartur Plateau that occurs at the western escarpment of the El-Kharga Oasis (Fig. 1 ). It lies between latitudes 25˚10 ̀and 25˚50 ̀ N and longitudes 29˚25 ̀and 30˚20 ̀ E. 2.2 General geology According to a geological map covering Egypt's middle latitudes, the phosphorite deposits are primarily found in Hanmraween area (Eastern Desert), in Sebaiya area (along the Nile Valley), and in the Western Desert in the Abu Tartur area 43 . Abu Tartur phosphate deposit, which is thought to be the thickest deposit in Egypt, covers an area of roughly 1200 km². The main region is located between El-Kharga Oasis in the east and El-Dakhla Oasis in the west includes Abu Tartur plateau 44 . Most of the sedimentary rocks of the Abu Tartur Plateau region are Pre-Maastrichtian to Quaternary in origin. From oldest to youngest, the Upper Cretaceous Lower Tertiary formations that make up the plateau's sedimentary sequence, especially on the eastern side (Fig. 2 ), are Taref Nubia sandstone formation, Quseir shale formation, Duwi formation (phosphorite), Dakhla shale formation, and Kurkur limestone formation 45 . In Egypt, the Duwi Formation which is constitutes the phosphatic rocks are of Late Cretaceous marine transgression that is overlain conformably by the deep marine shales and marls of the mid-Maastrichtian Dakhla Formation and unconformably overlies the fluvial shale sequence of the mid-Campanian Quseir Formation. The phosphate beds are interbedded with glauconites, argillaceous limestone, and black shale. The economic phosphate bed is at the base of the Duwi formation 46 . 2.3 Structural setting The Cretaceous and Lower Tertiary depositional environments in southern Egypt, especially Abu Tartur Plateau, is studied and discussed, based on a combination of paleontological and sedimentological studies, that repeated sea level fluctuations and large scale rejuvenation of pre-existing fault systems determined the Cretaceous to Early Tertiary evolutionary history of the depositional environments of southern Egypt 47 . The Dakhla (quite near Abu Tartur) and Assiut Basins formed in Central Egypt in the Late Jurassic or Early Cretaceous, marking the beginning of the progressive subsidence of large intracratonic depressions caused by these fault systems. Sea level variations and synsedimentary tectonism governed the transgressions and regressions that filled these depressions with sediments of continental and marine origin. Typical stable shelf tectonics is responsible for the structural components of El-Kharga-Dakhla stretch. The block movements in the basement are indicated by faults and, to a lesser extent, large gentle folds that are reflected on the surface. The thickness and lithology of the sedimentary cover, especially in its southern regions, most likely determine the kind and severity of the tectonics and deformations. The predominant tectonic characteristic is faults, which are more persistent and denser. The only area in the El-Kharga-Dakhla stretch in which crystalline basement outcrops with a thin sedimentary layer and noticeable basement rock up-arching can be observed is the southern portion of the Kharga Oasis. However, the broad warping and undulations is more noticeable in the west and northwest of El-Kharga, as Abu Tartur and El-Dakhla areas 48 . 3. Methodology and data processing Integration between gravity and magnetic methods is the most effective geophysical technique, which can disturbances in the Earth's gravity and magnetic fields to determine the density and magnetic susceptibility of rocks which reflecting the subsurface structures. In the present study the gravity and magnetic data were used to study the general picture of the predominant subsurface structures of the study area. The data were available in the form of reduced to the pole (RTP) aeromagnetic data compiled by the Egyptian General Petroleum Corporation EGPC (1989), as shown in Fig. 3 a and in form of Bouguer gravity data downloaded from the website, https://bgi.obs-mip.fr/ . The data was prepared in a contour map as shown in Fig. 3 b. The subsurface real lithology was recognised from the deep wells in or close to the study area as shown in Fig. 4 . Analysis and interpretation of RTP aeromagnetic and Bouguer gravity data were carried out through the following flowchart (Fig. 5 ). 3.1 Data processing Both RTP aeromagnetic and Bouguer gravity data should be filtered to condition the data set which making it easier to interpret the significance of gravity and magnetic anomalies in terms of geological features. In the present study, different filters will be applied on the Bouguer gravity and RTP aeromagnetic data. These filters can summarize as follows: The Fast Fourier Transform (FFT) was applied to the data for producing the energy spectrum curve. From the resulted curve, the depths to the shallow and deep sources 50 . The (regional) low pass filter highlights deep, high amplitude sources by suppressing small anomalies and high frequency noise. As a result, the anomalies appear broader and less sharp than those on the Bouguer anomaly and RTP aeromagnetic maps, while the regional field itself exhibits an overall smooth trend pattern. The (residual) high pass filter shows the high frequency and short wavelength anomalies of limited aerial extension that emphasize the shallow seated causative bodies 51 , 52 . The first vertical derivative filter measures the rate of change in the vertical direction of the gravity/magnetic field. The first vertical derivative also be positive over the source, zero over the edge, and negative outside of a vertical sided source 53 . The tilt derivative filter is the generalized local phase; it was applied to determine the vertical and inclined contacts and/or structure lines and used for mapping shallow basement structures and mineral exploration targets. On the other hand, tilt derivative has anomaly zero crossings located close to the edges of structures. TDR was estimated by dividing the vertical derivative by the total horizontal derivative as given in Eq. 1 54,55 . $$\:TDR=arctan\left(\frac{VDr}{THDR}\right)\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(1\right)$$ The analytic signal (AS) method or, total gradient method used for defining the edges (boundaries) of geologically anomalous magnetization or density distributions 56 . The analytic signal technique was discussed elsewhere by 53 , 57 , 58 as the square root of the squared sum of the vertical and horizontal derivatives of the magnetic field as given in Eq. 2. $$\:Asig=\sqrt{d{x}^{2}+d{y}^{2}+d{z}^{2}}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(2\right)$$ All applied filters were carried out by using Geosoft Oasis Montaj version 8.4 59 . In addition to the filters that were applied to the gravity and RTP aeromagnetic data, 2D gravity and magnetic modelling were applied. These models were applied to show the subsurface geologic sequence in the study area along definite directions. The sequence shows the subsurface geologic layers from the surface to the basement rocks. The subsurface structures prevailing in the study area also can be outlined from the model. The modelling process was carried out by applying an interactive modelling package running on GM-SYS through Geosoft Oasis Montaj version 8.4 59 . 4. Results and discussion The qualitative and quantitative interpretation of the Bouguer gravity and Aeromagnetic (RTP) data covering the study area are discussed below 4.1 Qualitative interpretation The qualitative interpretation of both gravity and magnetic data includes inspection of the shape, magnitude, amplitude and linearity of both gravity and magnetic anomalies in Bouguer gravity and RTP aeromagnetic maps, first vertical derivative, analytical signal, and tilt derivative maps. The gravity and magnetic lineaments that are corresponding to linear structures are also traced from all mentioned maps and presented on rose diagrams. 4.1.1 RTP aeromagnetic and Bouguer gravity maps The RTP aeromagnetic map of the study area (Fig. 3 a) shows the magnitudes of the magnetic anomalies vary from- 152.9 to + 103.7 nT. This great variation in the magnitude of magnetic anomalies is pointing to the area is highly affected by different structure sets. The central and southeastern parts of the area show lower magnitudes ranging from − 19.9 to -152.9 nT, which indicates that this area is uplifted with occurrence of granite basement rocks, which have low magnetic susceptibility in compared with the surrounding rocks. Whereas the northern part shows a high magnitude magnetic anomaly pointing to a magnetic source of high magnetic susceptibility in compared with other areas. The Bouguer gravity map of the study area (Fig. 3 b) shows major parts of the area are covered by positive gravity anomalies with values changing from 3.22 to 34.46 mGal. The central part of the study area, which includes Abu Tartur plateau, has maximum positive gravity values. This indicates that Abu Tartur plateau is an uplifted plateau, whereas the southwestern part, which has negative gravity values ranging from − 6.28 to -19.18 mGal, is downfaulted blocks. 4.1.2 Reginal and residual maps of both RTP and Bouguer data The high (residual) and low (regional) pass filters were carried out with a cutoff of 0.025 cycle/km. The regional magnetic and gravity anomalies are given in Figs. 6 a and 6 b. from these figures, it can see most of the magnetic and gravity anomalies are circular to oval, pointing circular to subcircular geologic features. The linear regional magnetic and gravity anomalies in W-E and NW-SE directions, indicating deep seated regional subsurface structures prevailing in both northern and central parts of the area. The residual anomaly maps of RTP aeromagnetic and Bouguer gravity are given in Figs. 7 a and 7 b. The residual RTP anomalies are of positive and negative magnitudes with circular to semi-circular shapes (Fig. 7 a). These anomalies are aligned mostly in W-E and NW-SE directions, indicating shallow geologic features and/or structures extending in the same directions. These two structure directions were recorded by different authors on the surface. The Bouguer gravity anomalies (Fig. 7 b) show well defined W-E and WNW-ESE extensions. The W-E extension pointing to predominant structure lineaments that were recorded by different authors as W-E strike slip faults. This fault trends are originated from the basement rocks and extended upward in the sedimentary cover. 4.1.3 FVD, TDR and AS of both RTP aeromagnetic and Bouguer gravity data The FVD is an effective tool to enhance the small and weak anomalies that reflect near surface geologic features and/or structures. Also, it is used to delineate lithologic contacts due to contrasts in susceptibility and density (Figs. 8 a and 8 b). The first vertical derivative map of the RTP aeromagnetic map (Fig. 8 a) shows that, the magnitudes of the magnetic anomalies are generally vary from − 0.028 to + 0.024 nT/m. Local anomalies of short wavelengths indicating shallow sources; however, zero contours are reflecting contacts or faults. From the map the main directions of the magnetized sources and lithologic as well as structure contacts are extending in the NNE-SSW, ENE-WSW, and W-E directions. The first vertical derivative map of the Bouguer gravity data (Fig. 8 b) reveals that the magnitudes of the anomalies are alternating positive and negative with values reach up to + 0.003 mGal/m and − 0.003 mGal/m, respectively. From the distribution of zero contour lines, the major lithologic contacts and/or structure lines are extending mainly in the ENE-WSW and W-E directions. The tilt derivative filter (TDR) was applied on both RTP aeromagnetic and Bouguer gravity data to determine the vertical and inclined contacts and/or structure lines. The zero contours are indicating the edges of the causative bodies which may be structure or lithologic contacts. The resulting maps are shown in Figs. 9 a and 9 b, respectively. The TDR map of the RTP aeromagnetic data (Fig. 9 a) shows that the radians of the anomalies vary from − 1.5 to + 1.3 radians. The tilt derivative anomalies are similar to the first vertical derivative anomalies in the shape and trends of the major structure. The TDR map of the Bouguer gravity data (Fig. 9 b), shows that the TDR values range between − 1.3 and + 1.3 radians. The TDR anomalies of the RTP aeromagnetic data are generally local anomalies with W-E extensions; however, the TDR of the Bouguer gravity data are three major anomalies extending nearly W-E. The local TDR anomalies of the RTP aeromagnetic data are pointing to local variation in the magnetic susceptibility within the basement rocks; however, the major anomalies on the TDR of the Bouguer gravity data are mainly extending in W-E direction pointing to major structure may originated from basement rocks and extended upward within the sedimentary cover. The analytical signal (AS) maps of both RTP aeromagnetic and Bouguer gravity data are shown in Figs. 10 a and 10 b. Generally, analytical signal maxima occur directly over faults and contacts. The analytical signal technique was applied to define the edges (boundaries) of bodies that are considered as basins or uplifts in the study area. From the AS map of the RTP aeromagnetic data (Fig. 10 a), the analytical signal values range from 0.0037 to 0.0377 nT. The maximum values are observed at the central and northern parts, which indicate that these parts of study area suffer from complicated structures; however, the minimum values are noticed at the western and southern parts, indicating to structure’s simplicity in those parts. The AS map of the Bouguer gravity data map (Fig. 10 b) shows that the analytical signal values range from 0.0005 to 0.0041 mGal. The northern part of the study area is characterized by low analytical signal anomalies indicating structural simplicity. However, the southern and central parts show high AS anomalies indicating complex structures. 4.2 Quantitative interpretation The quantitative interpretation in the present study was emphasized on 2D gravity and magnetic modelling utilizing the GM-SYS software. From the modelling results, the top surface of the Nubian sandstone layer and the basement surface were well defined and continues all over all models. These surfaces were marked and their depth related to the main sea level was exported as data XYZ files via the software. Furthermore, the top and bottom surfaces of the phosphatic rocks were also marked and exported in data XYZ files. From these files, the true thickness of the phosphatic rocks was estimated. Accordingly, a) depth or structure contour maps were prepared for the top surface of the Nubian Sandstone and basement surface, and b) an isopach map for phosphatic rocks. These maps were generated by utilizing Golden Surfer Software version15 60 . 4.2.1 2D gravity and magnetic modelling The 2D modelling was started by outlining the most important anomalies on the Bouguer gravity and RTP aeromagnetic maps. Such anomalies are corresponding to the predominant subsurface geologic features. About five profiles along definite lines crossing the main anomalies and extending in different directions to cover most of the study area. The technical steps of the modelling through GM-SYS of Oasis Montaj version 8.4 were as follows: Importing the data files, which include the coordinates and gravity or RTP aeromagnetic values from the gridded maps. The data was in XYZ format; X is the longitude, Y is the latitude, and Z is the Bouguer gravity or RTP aeromagnetic values in mGal and nT, respectively. The XY long/lat coordinates were converted into the UTM system by applying UTM projection Datum WGS1984, ellipsoid WGS 84, and Zone 35 N. Gridding data using Oasis Montaj, which provides seven different gridding algorithms to produce a grid. The gridded data is taken as input for producing a contour map. This map represents the aerial distribution of both Bouguer and RTP aeromagnetic anomalies, which are reflecting the subsurface geologic features and structures. The forward modelling was started by entering initial parameters of the subsurface sequence including density and magnetic susceptibility as well as depths to the boundaries which separate the expected subsurface layers or rock formations. Based on the entered initial parameters the program calculates the theoretical Bouguer gravity and RTP aeromagnetic values. After performing the calculation, the calculated values are compared to the observed one. Different adjustments through several iterations were carried out on the initial parameters to get the best fit between the observed and the calculated values. The adjustments and iterations were continued until get low RMS values and logic subsurface model. 4.2.1.1 Initial parameters for the 2D modelling For 2D gravity modelling, the initial parameters were the expected subsurface sedimentary sequences over the basement rocks. The expected subsurface sequence was collected from the published literature and the deep wells in the study area. For example, the Malab El-kheil well with depth to the basement rocks of 598 below sea level and the Ph2 well with a depth to the basement rocks of 755 m below sea level (Wells No. 8 and 10 respectively, in Fig. 11 ). The wells which not reached to the basement rocks such as those obtained from phosphate Egypt company, the depth to the basement was extrapolated based on the published work such as 61 . The sequence over the basement rocks is started by Nubian sandstone (Nubian formation) with thickness more than 300 m 62 , 63 , followed by variegated shale (Quseir formation) with thickness ranging from 100 to 225 m 64 , followed by Duwi formation which composed from phosphatic rocks and black shale with thickness varying from 20 to 30 m, the Duwi formation is followed by Dakhla shale (Dakhla formation) with thickness ranging from 100 to 135 m, followed by Limestone belonging to (KurKur formation) with thickness varying from 25 to 100 m 62 , 63 . The average density of the mentioned rock types was obtained from published literatures such as 65 – 68 and textbooks 52 , 69 – 71 . Accordingly, the average densities of the subsurface sequence in the study area can be summarized as follows: Limestone (2.5–2.7 g/cm³), Dakhla shale (1.77–2.6 g/cm³), Phosphatic rocks (1.52–2.97 g/cm³), Variegated shale (2.63–2.65 g/cm³), Nubian sandstone (2.65–2.67 g/cm³) and Basement rocks with density ranging from 2.52 to 3.45 g/cm³. For 2D magnetic modelling, the initial parameters were the magnetic susceptibility of the basement rocks and the overlying sedimentary cover. The magnetic susceptibility of the basement rocks in and around the study area is ranging from 0.001 to 0.0058 cgs units 72 which is equivalent to 0.013–0.073 in SI units and the magnetic susceptibility of the sedimentary cover is negligible. The five profiles which were selected for 2D modelling are shown on both RTP aeromagnetic and Bouguer maps (Figs. 11 a and 11 b). The profiles were nominated, A-À, B-B ̀, C-C ̀, D-D ̀ and E-E ̀. The Profile A-À is with length 64.006 km, Profile B-B ̀ is with length 85.041 km, Profile C-C ̀ is with length 85.714 km, Profile D-D ̀ is with length 84.936 km, and Profile E-E ̀ is with length 776.1624 km. Figures 12 and 13 show the 2D gravity and magnetic modeling and the obtained subsurface geologic models. The best fit between the calculated and observed gravity and magnetic values were obtained by following the RMS values through the GM-SYS of Oasis Montaj version 8.4. The accepted RMS values for all modeled profiles ranged between 3.549 and 8.014%. This range of RMS values falls within the commonly accepted range for RMS values, which is generally below 15%. The acceptance of the models beside the RMS values was the correspondence of the obtained models with the real subsurface sequence in the study area. Furthermore, the obtained models were controlled by the subsurface data of deep wells drilled in the study area. From the interpretation of five profiles and the corresponding 2D gravity and magnetic modelling, A-A`, B-B`, C-C`, D-D`, and E-E` Which extend SW to NE, SE to NW, WNW to ESE, SE to NW, and SSW to NNE, respectively, and pass through the available wells in the study area, the subsurface sequence can be summarized as follows: The basement rocks are situated at depths range from 138 to 798 m below sea level with average density ranges from 2.6 to 3.5 g/cm³ and magnetic susceptibility vary from 0.048 to 0.07 SI units. These remarkable variations in both density and magnetic susceptibility indicate lateral variations in mineral composition of the basement rocks that may reflect also lithologic contacts between different basement rock types. The Nubian sandstone layer, which is defined as Nubian Sandstone Formation in literatures has an average thickness ranges from 90 to 525.53 m with average density of 2.66 g/cm³. This great variation in the thickness may indicate that this formation is highly affected by faulting. The variegated shale layer, which is defined as Quseir Formation in literatures, has an average thickness ranges from 58.76 to 374.13 m with average density of 2.1 g/cm³. This formation appeared on the models as continuous shale layer and silty shale lenses with density 2.13 g/cm³ in some places. The lenses have average thickness range from 498.86 to 765.524m. These high values of thickness may be due to that the silty shale lenses deposited in deep lagoon or lakes environment, and with density 2.13 g/cm³. The Dakhla shale layer, which is defined as Dakhla Formation in the literatures, is observed with average density 1.8 g/cm³ as a continuous layer along the D-D` model by thickness ranges from 30.61 to 510.20 m. Whereas, appeared as separated blocks along A-A`, B-B`, C-C`, and E-E` models with average thickness varies from 201.5 to 396.15 m. The blocks are predominant at the parts which may be affected by faulting and weathering. The limestone layer, which is defined as Kurkur Formation in the literatures, with average density 2.7 g/cm³ has appeared as capping the sedimentary sequence, and hence its actual thickness is not estimated. The main objective of the present study was targeted to the mode of occurrence of the phosphatic rocks, the parts of the models which have the phosphatic rocks are zoomed out and plotted below the models. The phosphatic rocks are defined as Duwi Formation in the literatures. From the zoom out parts, the phosphatic rocks with average density 2 g/cm³ are observed as a continuous layer along A-A` and D-D` models with average thickness ranges from 1.75 to 19.9 m and as a disconnected layer along B-B`, C-C`, and E-E` models with average thickness varies from 1.9 to 23.46 m. This great thickness variations and disconnection in the phosphatic rocks may be due faults that are predominant in the study area. Lateral thickness variation of subsurface sequence from the Nubian sandstone at the bottom to the Kurkur Formation at the top may indicate that all the sequence is affected by structures originating from the basement rocks and extending upward in the sedimentary cover. 4.2.1.2 Depth or structure contour map of the basement surface From the prepared map of the basement surface in the study area (Fig. 14 ), the main structures are two syncline folds located at the northern and eastern parts of the study area. These syncline folds are of asymmetrical double plunging with an axis extending NE-SW direction. Another symmetrical plunging syncline fold with an axis extending NE-SW is observed at the northwest part of the study area. At the western part, the contours show a basin structure. There are four anticlines located in the northern, eastern, western, and southern parts of the study area. The anticline fold in the northern part is asymmetrical, plunging with an axis extending NE-SW direction. The anticline fold in the eastern part is symmetrical plunging with an axis extending WNW-ESE. The anticline fold in the southeastern part is asymmetrical plunging with an axis extending WNW-ESE. The anticline fold in the western part is symmetrical plunging with an axis extending NNE-SSW. Two dextral strike slip faults are also noticed; the first one is in the northern part of the study area extending WNW-ESE and another one is in the southern part extending W-E. 4.2.1.3 Depth or Structure contour map of the top Nubian sandstone layer From the structure contour map of the top Nubian sand surface in the study area (Fig. 15 ), the main structures are five synclines located in the northern, eastern, western, southeastern, and southern parts of the study area. The syncline fold at the northern part is asymmetrical double plunging with an axis extending NE-SW. The syncline fold at the western part of the study is asymmetrical double plunging with an axis extending NNW-SSE. The syncline fold at the eastern part is symmetrical double plunging with an axis extending NNW-SSE. The syncline fold at the southeastern part is asymmetrical double plunging with an axis extending W-E. The syncline fold at the southern part of the study area is asymmetrical plunging with an axis extending WNW-ESE. Two anticline folds are defined in the northern and southern parts of the study area. The anticline fold at the northern part is asymmetrical plunging with an axis extending NE-SW. The anticline fold at the southeastern part is asymmetrical plunging with an axis extending NW-SE. Six normal faults are observed at the middle part of the study area, bounding Abu Tartur plateau and extending NNW-SSE, NE-SW, and NW-SE. The downthrows of these faults are due to the lowlands outside of the plateau. Two dextral strike slip faults, one of them in the northern part of the study area extending WNW-ESE direction and the other one in the southern part extending W-E direction. 4.2.1.4 Thickness or Isopach map of the phosphatic rocks The prepared thickness map of the phosphatic rock (Fig. 16 ) show that: The subsurface thickness of the phosphatic rocks ranges between 0.8 to 32 m. This great lateral variation in the thickness is related to the predominant structures. The maximum thickness is recorded in northeast and southwest parts of Abu Tartur plateau. Figure 17 illustrates the combination of the structure contour map of the basement surface (Fig. 14 ), the structure contour map of the top Nubian sandstone surface (Fig. 15 ), and the thickness map of phosphatic rocks (Fig. 16 ). From the cumulative figure (Fig. 17 ), It can be noticed that the maximum thickness of the phosphatic rocks is observed at the troughs of the syncline folds, which are located northeast and southwest of Abu Tartur plateau. Abu Tartur plateau is bounded by several faults with downthrow outward from the plateau. So, the present location of the Abu Tartur mine was mostly not the best location for underground mining and, accordingly, not economic. 4.3 Structure trends analysis of lineaments detected from Bouguer gravity and RTP aeromagnetic maps The most important step in interpreting Bouguer gravity and RTP aeromagnetic data is turning them into tectonic information. Tectonic interpretation of a particular area is greatly influenced by the main structural characteristics on the basement surface that affect the sedimentary cover above. Main tectonic trends influencing the study region are visualized in the current work using trend analysis of the gravitational and magnetic fields as well as their derivatives. The digitizing techniques available in Rockware Software version15 73 were used in tracing and measuring the structural lineaments. The main structural trends prevailing in the study area can be detected as follows: N-S trend, which azimuths from 0˚to 5˚ to the west or the east, NNE trend from 5˚ to 30˚ to the east, NNW trend from 5˚to 30˚ to the west, NE trend from 30˚to 60˚ to the east, NW trend from 30˚to 60˚ to the west, ENE trend from 60˚to 85˚ to the east, WNW trend from 60˚to 85˚ to the west and W-E trend from 85˚to 90˚ to the west or east. (Table 1 ) summarizes the structural trends extracted from the gravity and magnetic data across different processing stages, including RTP, Bouguer, regional, residual, FVD, TDR, and AS maps. Table 1 Summary of the trends detected from different maps of the study area. Directions Corresponding maps Domain Type 1st Trends 2nd Trends 3rd Trends Major Trends Minor Trends Regional RTP Regional Bouguer Local RTP Local Bouguer W-E AS gravity, FVD RTP, FVD gravity, residual RTP, residual gravity, TDR RTP, TDR gravity RTP, regional gravity AS RTP, Bouguer gravity, regional RTP √ √ √ √ ENE AS RTP, RTP, TDR RTP FVD RTP, FVD gravity, regional RTP, regional gravity, residual RTP, residual gravity Bouguer gravity, TDR gravity √ √ √ √ NNE Bouguer gravity, FVD RTP AS gravity, FVD gravity, regional gravity, TDR RTP Regional RTP, Residual RTP, TDR gravity √ √ √ × NW Regional RTP AS RTP, Bouguer gravity, FVD gravity, regional gravity Residual RTP √ √ √ × NNW Regional gravity AS RTP, Bouguer gravity FVD gravity, RTP, regional RTP, TDR RTP √ √ × × WNW Regional gravity AS RTP, RTP, regional RTP, TDR gravity Bouguer gravity, FVD RTP, FVD gravity, residual gravity √ √ × √ NE Bouguer gravity, regional gravity AS RTP, AS gravity, RTP, regional RTP √ √ × × a) W-E Trend This is the most prominent trend recorded in the study area, it was found as first order in residual RTP, residual gravity, FVD RTP, FVD gravity, TDR RTP, TDR gravity and AS gravity (Figs. 19a, 19b, 19c, 19d, 19e, 19f and 20b), recorded as second order in RTP and regional gravity (Figs. 18a and 18d), and as third order in Bouguer gravity, regional RTP, and AS RTP (Figs. 18b, 18c and 20a). This trend has been recorded by several recent studies 56,74-76 . b) ENE-WSW Trend This trend has been verified through several recent studies 77,78 . In RTP, TDR RTP, and AS RTP (Figs. 18a, 19e and 20a) this trend is recorded as first order, observed as second order in regional RTP, regional gravity, residual RTP, and residual gravity, FVD RTP, and FVD gravity (Figs. 18c, 18d, 19a, 19b, 19c and 19d), and in the Bouguer gravity and TDR gravity (Figs. 18b and 19f), this trend is characterized as third order c) NNE-SSW Trend This trend is observed as the first order in Bouguer gravity and FVD RTP (Figs. 18b and 19f), as second order in regional gravity, FVD gravity, TDR RTP, and AS gravity (Figs. 18d, 19d, 19e and 20b), and as third order in regional RTP, residual RTP and TDR gravity (Figs. 18c, 19a and 19f). This trend has been identified by many authors 79-81 . d) NW-SE Trend This trend manifests as a first order in the regional RTP map (Fig. 18c), as a second order in Bouguer gravity, regional gravity, FVD gravity, and AS RTP (18b, 18d, 19d and 20a), and as a third order in residual RTP (Fig. 19a). This trend has been recorded by 67,76,82,83 . e) NNW-SSE Trend On the regional gravity (Fig. 18d), this trend appears as first order. Second order signature in Bouguer gravity and AS RTP (Figs. 18b and 20a), whereas third order expression in RTP, Regional RTP, FVD gravity and TDR RTP (Figs. 18a, 18c, 19d and 19e) This trend has been confirmed by several studies 74,84,85 . f) WNW-ESE Trend This trend is delineated as the first order in regional gravity (Fig. 18d), recorded as the second order in RTP, regional RTP, TDR gravity, and AS RTP (Figs. 18a, 18c, 19e and 20a), and in the Bouguer gravity, residual gravity, FVD RTP, and FVD gravity (Figs. 18b, 19b, 19c and 19d), this trend is characterized as the third order. This trend has been identified by 67,74,86,87 . g) NE-SE Trend This trend has been verified through 74,75,84 . This trend is observed as second order in Bouguer gravity and regional gravity (Figs. 18b and 18d). It has appeared as a third order in RTP, regional RTP, AS RTP, and AS gravity (Figs. 18a, 18c, 20a and 20b). 5. Conclusions This study applied an integrated geophysical approach, combining aeromagnetic (RTP) and Bouguer gravity data, to characterize the subsurface structural framework of Abu Tartur Phosphate Mine (ATPM). The results provide critical insights into the geological controls on phosphate distribution, which are essential for optimal mine planning and sustainable resource utilization. Qualitative interpretation of the gravity and magnetic data revealed several dominant structural trends in the region, including W-E, ENE, NNE, NW, NNW, WNW, and NE directions. These trends are associated with both deep seated basement structures and shallower features observable near the surface. Quantitative analysis through 2D modelling confirmed the presence of complex subsurface structures, mainly comprising normal and strike slip faults as well as plunging and double plunging folds with axes trending NE-SW, NNW-SSE, and NW-SE. The remarkable feature of this study is the significant lateral variation in the thickness of the phosphatic rocks, ranging from 0.8 to 32 meters. The thinnest layers were identified in the currently exploited central plateau area, which likely contributed to the subeconomic performance and eventual closure of the underground mine. Conversely, the thickest phosphate deposits were found at the troughs of synclinal folds located northeast and southwest of the plateau zones that offer substantially greater mining potential. These results clearly demonstrate that the current ATPM site was suboptimal for underground mining and that better informed geophysical analysis could have prevented misallocation of resources. The integration of gravity and magnetic data, supported by borehole data and geological modelling, proved essential for delineating structurally controlled phosphate rich zones. This approach not only enhances the economic feasibility of future mining operations at ATPM but also provides a replicable framework for mineral exploration in structurally complex terrains elsewhere. Ultimately, this research underscores the importance of multidisciplinary geophysical characterization in guiding resource extraction, reducing risk and supporting long term sustainability in the mining sector. Declarations Funding The funding was provided by Science and Technology Development Fund through the Open Access agreement. Data availability No additional data to declare. All data generated or analyzed during this study are included within this manuscript Competing interests The authors declare no competing interests. Author Contribution G.MK.A conceptualized the study, performed geophysical data processing and interpretation, and led the manuscript writing. M.M.S contributed to the geological framework, structural analysis, and validation of results. G.Y.B. assisted in data visualization, map generation, and modeling. M.H.A. contributed to literature review, field data collection, and manuscript editing. All authors reviewed and approved the final version of the manuscript. References Gorman, M. R. & Dzombak, D. A. A review of sustainable mining and resource management: Transitioning from the life cycle of the mine to the life cycle of the mineral. Resources Conservation Recycling 137 , 281-291.https://doi.org/10.1016/j.resconrec.2018.06.001 (2018). Lamghari, K. et al. Sustainable phosphate mining: Enhancing efficiency in mining and pre-beneficiation processes. Journal of Environmental Management 358 , 120833. https://doi.org/10.1016/j.jenvman.2024.120833 (2024). Mirzehi, M. & Afrapoli, A. M. Sustainable long-term production planning of open pit mines: An integrated framework for concurrent economical and environmental optimization. Resources Policy 94 , 105131.https://doi.org/10.1016/j.resourpol.2024.105131 (2024). Pavloudakis, F., Roumpos, C. & Spanidis, P.-M. Vol. 16 8393 (Sustainability 2024). Batterham, R. The mine of the future–even more sustainable. Minerals Engineering 107 , 2-7.https://doi.org/10.1016/j.mineng.2016.11.001 (2017). Littleboy, A. et al. A sustainable future for mining by 2030 Insights from an expert focus group. The extractive industries society 6 , 1086-1090. https://doi.org/10.1016/j.exis.2019.11.005 (2019). Monteiro, N. B. R., da Silva, E. A. & Neto, J. M. M. Sustainable development goals in mining. Journal of Cleaner Production 228 , 509-520. https://doi.org/10.1016/j.jclepro.2019.04.332 (2019). Hellal, F., El-Sayed, S., Zewainy, R. & Amer, A. Importance of phosphate pock application for sustaining agricultural production in Egypt. Bulletin of the National Research Centre 43 , 1-11.https://doi.org/10.1186/s42269-019-0050-9 (2019). Lyon, C. et al. Five pillars for stakeholder analyses in sustainability transformations: The global case of phosphorus. Environmental science policy 107 , 80-89. https://doi.org/10.1016/j.envsci.2020.02.019 (2020). Gupta, D., Chatterjee, S., Datta, S., Veer, V. & Walther, C. Role of phosphate fertilizers in heavy metal uptake and detoxification of toxic metals. Chemosphere 108 , 134-144.https://doi.org/10.1016/j.chemosphere.2014.01.030 (2014). Bindraban, P. S., Dimkpa, C. O., Pandey, R. & Soils, F. o. Exploring phosphorus fertilizers and fertilization strategies for improved human and environmental health. Biology 56 , 299-317.https://doi.org/10.1007/s00374-019-01430-2 (2020). Cordell, D., Drangert, J.-O. & White, S. The story of phosphorus: global food security and food for thought. Global environmental change 19 , 292-305. https://doi.org/10.1016/j.gloenvcha.2008.10.009 (2009). Hussein, M., Ibrahim, A. & Imbaby, S. Application of the rock mass classification systems to pillar design in longwall mining for Abu-Tartur longwall phosphate mining conditions. JES. Journal of Engineering Sciences 41 , 2012-2020. https://dx.doi.org/10.21608/jesaun.2013.114931 (2013). Al-Wakeel, M. I. Effect of mechanical treatment on the mineralogical constituents of Abu-Tartour phosphate ore, Egypt. International Journal of Mineral Processing 75 , 101-112.https://doi.org/10.1016/j.minpro.2004.05.004 (2005). Orabi, A. et al. Extraction of rare earth elements from Abu–Tartour wet process phosphoric acid using synthesized salicylaldehyde azine. Minerals Engineering 122 , 113-121.https://doi.org/10.1016/j.mineng.2018.03.037 (2018). Hussein, M., Ibrahim, A. & Imbaby, S. Load calculations and selection of the powered supports based on rock mass classification and other formulae for Abu-Tartur longwall phosphate mining conditions. JES. Journal of Engineering Sciences 41 , 1728-1742.https://dx.doi.org/10.21608/jesaun.2013.114900 (2013). Hussein, M., Imbaby, S. & Ibrahim, A. Panel width affected by rock mass classifications (Abu-Tartur Phosphate Mines). JES. Journal of Engineering Sciences 41 , 1364-1379.https://dx.doi.org/10.21608/jesaun.2013.114796 (2013). Reedman, J. Techniques in mineral exploration . (Springer Science & Business Media, 2012). Bhadra, B. et al. Integrated remote sensing and geophysical techniques for shallow base metal deposits (Zn, Pb, Cu) below the gossan zone at Kalabar, Western Aravalli Belt, India. Journal of Applied Geophysics 191 , 104365.https://doi.org/10.1016/j.jappgeo.2021.104365 (2021). Faruwa, A. R. et al. Airborne magnetic and radiometric mapping for litho-structural settings and its significance for bitumen mineralization over Agbabu bitumen-belt southwestern Nigeria. Journal of African Earth Sciences 180 , 104222. https://doi.org/10.1016/j.jafrearsci.2021.104222 (2021). Eldougdoug, A. et al. Exploring gold mineralization in altered ultramafic rocks in south Abu Marawat, Eastern Desert, Egypt. Scientific Reports 13 , 7293.https://doi.org/10.1038/s41598-023-33947-w (2023). Pelton, W. H., Ward, S. H., Hallof, P., Sill, W. & Nelson, P. H. Mineral discrimination and removal of inductive coupling with multifrequency IP. Geophysics 43 , 588-609. https://doi.org/10.1190/1.1440839 (1978). Nelson, P. & Van Voorhis, G. Estimation of sulfide content from induced polarization data. Geophysics 48 , 62-75.https://doi.org/10.1190/1.1441408 (1983). Gurin, G., Titov, K. & Ilyin, Y. Induced polarization of rocks containing metallic particles: Evidence of passivation effect. Geophysical Research Letters 46 , 670-677. https://doi.org/10.1029/2018GL080107 (2019). Alao, J. O., Lawal, K. M., Dewu, B. B. M. & Raimi, J. The studying of magnetic anomalies due to shallow underground targets and the environmental applications. Results in Earth Sciences 2 , 100016.https://doi.org/10.1016/j.rines.2024.100016 (2024). Li, K. et al. Non-invasive geophysical methods for monitoring the shallow aquifer based on time-lapse electrical resistivity tomography, magnetic resonance sounding, and spontaneous potential methods. Scientific Reports 14 , 7320.https://doi.org/10.1038/s41598-024-58062-2 (2024). Saleh, A. & Gabr, S. S. Application of magnetic data and satellite spectral imaging in identifying gold mineralization zones and its associated subsurface structures at Fawakheir-Attala area, Central Eastern Desert, Egypt. Environmental Earth Sciences 83 , 500.https://doi.org/10.1007/s12665-024-11776-y (2024). Bahi, A. et al. Characterization of Mineral Meposits Using the Magnetic Method: The Case of the Aïn Beida Mine in Bouarfa, Morocco. Civil Environmental Engineering 20 , 571-579.https://doi.org/10.2478/cee-2024-0043 (2024). Oladejo, O. P., Akinlabi, I. A. & Ogunkoya, C. O. Subsurface Qualitative Investigation for Mineral Exploration using Aeromagnetic Data. Dutse Journal of Pure and Applied Sciences 9 , 192-203.https://dx.doi.org/10.4314/dujopas.v9i4a.18 (2024). Doyle, H. A. Geophysical exploration for gold—a review. Geophysics 55 , 134-146.https://doi.org/10.1190/1.1442820 (1990). Nabighian, M. N. et al. Historical development of the gravity method in exploration. Geophysics 70 , 63ND-89ND.https://doi.org/10.1190/1.2133785 (2005). Li, H. et al. Prospecting for ophiolite-type chromite deposit in Sartohay, West Junggar (NW China): Constraints from geological and geophysical data. Ore Geology Reviews 156 , 105379.https://doi.org/10.1016/j.oregeorev.2023.105379 (2023). Hornicka, E., Targosz, P., Loska, M. & Wojdyła, M. in NSG2020 3rd Conference on Geophysics for Mineral Exploration and Mining. 1-5 (European Association of Geoscientists & Engineers). Shirazy, A., Shirazi, A., Nazerian, H., Khayer, K. & Hezarkhani, A. Geophysical study: Estimation of deposit depth using gravimetric data and Euler method (Jalalabad iron mine, kerman province of IRAN). Open Journal of Geology 11 , 340-355. https://doi.org/10.4236/ojg.2021.118018 (2021). Union, J. I. G. Geophysical exploration for manganese-some first hand examples from Keonjhar district, Orissa. J. Ind. Geophys. Union 13 , 149-161 (2009). Zhang, J. et al. Deep mineral exploration of the Jinchuan Cu–Ni sulfide deposit based on aeromagnetic, gravity, and CSAMT methods. Minerals Engineering 10 , 168 https://doi.org/10.3390/min10020168 (2020). Sun, J., Dong, L., Zhang, T., Shen, P. & Liu, D. J. C. E. J. Efficient recovery of copper from copper smelting slag by gravity separation combined with flotation. Chemical Engineering Journal , 153159.https://doi.org/10.1016/j.cej.2024.153159 (2024). Hasbrouck, W. & Hadsell, F. A. in Second Symposium on the Geology of Rocky Mountain Coal, Proceedings: Colorado Geological Survey Resource Series. 187-218. Xue, G. et al. Delineation of sedimentary bauxite deposits in Shaanxi Province using the gravity and transient electromagnetic methods. Ore Geology Reviews 144 , 104865. https://doi.org/10.1016/j.oregeorev.2022.104865 (2022). Ali, M. et al. Geoelectrical tomography data processing and interpretation for Pb-Zn-Ag mineral exploration in Nash Creek, Canada , in E3S Web of Conferences. p.00003 EDP Sciences (2020). Ali, M. A. H. et al. Integration of electrical resistivity tomography and induced polarization for characterization and mapping of (Pb-Zn-Ag) sulfide deposits. Minerals Engineering 13 , 986.https://doi.org/10.3390/min13070986 (2023). Eldosouky, A. M. et al. in Geospatial Analysis Applied to Mineral Exploration 189-231 (Elsevier, 2023). Glenn, C. R. & Arthur, M. A. Anatomy and origin of a Cretaceous phosphorite‐greensand giant, Egypt. Sedimentology 37 , 123-154.https://doi.org/10.1111/j.1365-3091.1990.tb01986.x (1990). Zidan, I. J. Evaluation of phosphorite and Uranium in Lower phosphorite Member, Duwi Formation at Kummer area, South Esna, West Nile Valley, Egypt. J ournal of Sedimentological society of Egypt 21 , 143-154 (2013). Zidan, I. Geological and Mineralogical Studies of Abu Tartur Phosphates, Western Desert-Egypt, M. Sc. Thesis , Fac. of Sci. Geology Dept., Al-Azhar University, (1998). Baioumy, H. & Tada, R. Origin of late Cretaceous phosphorites in Egypt. Cretaceous Research 26 , 261-275.https://doi.org/10.1016/j.cretres.2004.12.004 (2005). Hendriks, F., Luger, P., Bowitz, J. & Kallenbach, H. Evolution of depositional environments of SE-Egypt during the Cretaceous and lower Tertiary. (1987). Said, R. The geology of Egypt: balkema. Rotterdam, Brookfield 734 (1990). Coral, C. Geological map of Egypt, scale1:500,000. The Egyptian General Petroleum Corporation (EGPC), Egypt (1987). Spector, A. & Grant, F. Statistical models for interpreting aeromagnetic data. Geophysics 35 , 293-302.https://doi.org/10.1190/1.1440092 (1970). Blakely, R. J. Potential theory in gravity and magnetic applications . (Cambridge university press, 1996). Telford, W. M., Geldart, L. P. & Sheriff, R. E. Applied geophysics . (Cambridge university press, 1990). Nabighian, M. N. Toward a three-dimensional automatic interpretation of potential field data via generalized Hilbert transforms: Fundamental relations. Geophysics 49 , 780-786.https://doi.org/10.1190/1.1441706 (1984). Verduzco, B., Fairhead, J. D., Green, C. M. & MacKenzie, C. New insights into magnetic derivatives for structural mapping. The leading edge 23 , 116-119. https://doi.org/10.1190/1.1651454 (2004). Miller, H. G. & Singh, V. Potential field tilt—a new concept for location of potential field sources. Journal of applied Geophysics 32 , 213-217. https://doi.org/10.1016/0926-9851(94)90022-1 (1994). Mohamed, H. S., Senosy, M. M. & Abdel Zaher, M. Interactive interpretation of airborne gravity, magnetic, and drill-hole data within the crustal framework of the northern Western Desert, Egypt. Journal of Applied Geophysics 134 , 291-302. https://doi.org/10.1016/j.jappgeo.2016.09.002 (2016). Roest, W. R., Verhoef, J. & Pilkington, M. Magnetic interpretation using the 3-D analytic signal. Geophysics 57 , 116-125.https://doi.org/10.1190/1.1443174 (1992). MacLeod, I. N., Jones, K. & Dai, T. F. 3-D analytic signal in the interpretation of total magnetic field data at low magnetic latitudes. Exploration geophysics 24 , 679-688. https://doi.org/10.1071/EG993679 (1993). Geosoft, I. OASIS Montaj. version 8.4 user guide. Toronto, Canada: Geosoft Incorporated (2015). Software, G. Surfer®: Contouring and 3D mapping for scientists and engineers (Version 15) [Computer software]. Golden Software (2017). Senosy, M. Application of density contrast stripping in studying subsurface geologic structures: a case study El-Kharga Oasis, western Desert, Egypt. Egyptian J. Geol. 47 , 387-404 (2003). Rizk, S. A. M. Highlights on the beneficiation trials of the Egyptian phosphate ores. JES. Journal of Engineering Sciences 50 , 1-21. https://dx.doi.org/10.21608/jesaun.2021.100795.1083 (2022). Elmaadawy, K. G., Ezz El Din, M., Khalid, A. & Abouzeid, A. Mineral industry in Egypt–part II non metallic commodities–phosphate rocks. J Min World Express 4 , 1-18. http://dx.doi.org/10.14355/mwe.2015.04.001 (2015). Mahmoud, M. S. Palynology and palaeoenvironment of the Quseir Formation (Campanian) from central Egypt. Journal of African Earth Sciences 36 , 135-148. https://doi.org/10.1016/S0899-5362(03)00047-2 (2003). Senosy, M., Youssef, M. & Zaher, M. A. Sedimentary cover in the South Western Desert of Egypt as deduced from Bouguer gravity and drill-hole data. Journal of African Earth Sciences 82 , 1-14.https://doi.org/10.1016/j.jafrearsci.2013.02.001 (2013). Ibrahim, S., El Kammar, A. & Guda, A. Characterization and separation of pyrite from Abu Tartur black shale. International Journal of Mining Science Technology 25 , 565-571.https://doi.org/10.1016/j.ijmst.2015.05.008 (2015). Zaher, M. A., Senosy, M., Youssef, M. & Ehara, S. Thickness variation of the sedimentary cover in the South Western Desert of Egypt as deduced from Bouguer gravity and drill-hole data using neural network method. Earth planets space 61 , 659-674. https://doi.org/10.1186/BF03353175 (2009). El Maghraby, A. Phosphate mining wastes at Abu Tartur mine area, Western Desert of Egypt. Australian Journal of basic and Applied Sciences 10 , 231-248 (2012). Telford, W., Geldart, L., Sheriff, R. & Keys, D. J. L. p. Applied geophysics cambridge university press. (1976). Sharma, P. V. Environmental and engineering geophysics . (Cambridge university press, 1997). Kearey, P., Brooks, M. & Hill, I. An introduction to geophysical exploration . Vol. 4 (John Wiley & Sons, 2002). El-Sirafe, A. M., El-Gamili, M. M., El-Manawy, M. E. & El-Mdiegy, M. A. Structural Interpretation of the Airborne Magnetic Survey Data of Kharga-Dakhla Oases Area, Southern Western Desert, Egypt Sci. J. Fac Sci Minufiya University 14 , 233-257 (2000). RockWare. RockWorks15: Geological data management, mapping, and visualization software. RockWare, Inc., Golden, Colorado, USA (2013) . Saada, S. & El-Khadragy, A. An integrated study of gravity and magnetic data on west El-Minya area, Western Desert, Egypt. Journal of American Science 11 , 169-184. https://doi.org/10.7537/marsjas111215.23 (2015). Saada, S. A. et al. Understanding the structural framework controlling the sedimentary basins from the integration of gravity and magnetic data: A case study from the east of the Qattara Depression area, Egypt. Journal of King Saud University-Science 34 , 101808. https://doi.org/10.1016/j.jksus.2021.101808 (2022). Mohamed, A., Alarifi, S. S. & Abdelrady, A. Sedimentary cover and structural trends affecting the groundwater flow in the Nubian Sandstone Aquifer System: Inferences from geophysical, field and geochemical data. Frontiers in earth science 11 , 1173569. https://doi.org/10.3389/feart.2023.1173569 (2023). Elmasry, A., Abdel Zaher, M., Madani, A. & Nassar, T. Exploration of Geothermal Resources Utilizing Geophysical and Borehole Data in the Abu Gharadig Basin of Egypt’s Northern Western Desert. Pure and Applied Geophysics 179 , 4503-4520. https://doi.org/10.1007/s00024-022-03180-z (2022). Kamal, M. et al. Integrated geophysical techniques applied for petroleum basins structural characterization in the central part of the Western Desert, Egypt. Open Chemistry 21 , 20220293.https://doi.org/10.1515/chem-2022-0293 (2023). Abdelhamed, B. M., Awad Sultan Araffa, S. & Abdelhafeez, T. Geophysical studies around abu gharadig basin, North Western desert, Egypt. Exploration Geophysics 54 , 329-351.https://doi.org/10.1080/08123985.2022.2123736 (2023). Mohamed, W. H., Elyaseer, M. H. & Sabra, M. E. M. Structural lineament analysis of the Bir El-Qash area, Central Eastern Desert, Egypt, using integrated remote sensing and aeromagnetic data. Scientific Reports 13 , 21569.https://doi.org/10.1038/s41598-023-48660-x (2023). Araffa, S. et al. Geophysical and Remote Sensing Data for Delineating Structural Elements at El Hammam Area, Northern Part of Western Desert, Egypt. Geotectonics 58 , 218-233. https://doi.org/10.1134/S0016852124700146 (2024). Youssef, M. I. Structural pattern of Egypt and its interpretation. AAPG Bulletin 52 , 601-614. https://doi.org/10.1306/5D25C44D-16C1-11D7-8645000102C1865D (1968). Abdel Zaher, M. et al. Origin of mysterious geothermal gas emissions in the middle of the Western Desert, stable shelf area, Dakhla Oasis, Egypt. Scientific Reports 13 , 16466. https://doi.org/10.1038/s41598-023-43492-1 (2023). Saad, M., El-Khadragy, A., Shabaan, M. & Azab, A. An integrated study of gravity and magnetic data on South Sitra area, Western Desert, Egypt. J Appl Sci Res 6 , 616-636 (2010). Saada, S., Zahra, H. & El-Khadragy, A. Structural pattern and crustal modeling of the central northern part of Egypt, using Bouguer gravity data. Journal. Applied sciences research 9 (2013). Khalil, A., Hafeez, T. H. A., Saleh, H. S., Mohamed, W. H. & Geophysics. Inferring the subsurface basement depth and the structural trends as deduced from aeromagnetic data at West Beni Suef area, Western Desert, Egypt. NRIAG Journal of Astronomy 5 , 380-392. https://doi.org/10.1016/j.nrjag.2016.08.001 (2016). Elmaadawy, K. G. & El-Ashmony, M. R. Tectonostratigraphic evolution of the new frontier Foram Basin and implications for hydrocarbon potential, Western Desert, Egypt. Journal of African Earth Sciences 177 , 104142.https://doi.org/10.1016/j.jafrearsci.2021.104142 (2021). Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6981993","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":482912558,"identity":"08d4fba5-7991-4bb2-8d97-921a6a30148a","order_by":0,"name":"Gehad Ahmed","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIiWNgGAWjYFACHjACgw8MFRCGBHFa2BgYZzCcIVkLYxsRWuTdew9+eMOwTU5+fvPDhp/z7BK3MzAfvM3DYGPXgEOL4ZlzyZJzGG4bGxxjM2zs3ZacuLOBLdmahyEtGaeWGTkG0jwMtxM3sDGYP+Ddxpy44QCPGVDkcDIuhxnOf2P8G6Rlfhv7x8a/c+qBWvi/AbX8x6lFXgJs5u3EhmM8hs28DYdBtrABRQ7Y4dJiwJNjZjnHAOSXnMJmmWPHjTccZjMGiiQn4LSl/YzxjTcVt+Xkm49vbHxTUy274XjzQ6CInT1OWw6ASWQhZohIYgMuW3BJMOC0ZRSMglEwCkYcAABx6Vbo1pMwQAAAAABJRU5ErkJggg==","orcid":"","institution":"Assiut University","correspondingAuthor":true,"prefix":"","firstName":"Gehad","middleName":"","lastName":"Ahmed","suffix":""},{"id":482912559,"identity":"b03c5abe-a25e-46b3-81d1-9dd2fe2dc178","order_by":1,"name":"Mahmoud Senosy","email":"","orcid":"","institution":"Assiut University","correspondingAuthor":false,"prefix":"","firstName":"Mahmoud","middleName":"","lastName":"Senosy","suffix":""},{"id":482912560,"identity":"be916d07-4949-47e6-bb27-89676031adeb","order_by":2,"name":"Gamal Boghdady","email":"","orcid":"","institution":"Assiut University","correspondingAuthor":false,"prefix":"","firstName":"Gamal","middleName":"","lastName":"Boghdady","suffix":""},{"id":482912561,"identity":"625331c2-b26c-44d6-baf6-e9e2a8c4f55b","order_by":3,"name":"Mosaad Ali","email":"","orcid":"","institution":"Assiut University","correspondingAuthor":false,"prefix":"","firstName":"Mosaad","middleName":"","lastName":"Ali","suffix":""}],"badges":[],"createdAt":"2025-06-26 09:38:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6981993/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6981993/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-026-48186-y","type":"published","date":"2026-04-21T15:56:55+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":86496542,"identity":"c3b0fa5b-587e-4faf-8537-4be1f8800cf0","added_by":"auto","created_at":"2025-07-11 10:10:51","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":8255433,"visible":true,"origin":"","legend":"\u003cp\u003eLocation map of the study area (generated using ArcMap version 10.8 https://desktop.arcgis.com/en/arcmap/latest/get-started/setup/arcgis-desktop-system-requirements.htm ).\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/bbb1cbb9aa82727fd99f6bf0.png"},{"id":86496543,"identity":"2af42c84-93f7-4ded-b003-a5da49ba3a08","added_by":"auto","created_at":"2025-07-11 10:10:51","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":7833884,"visible":true,"origin":"","legend":"\u003cp\u003eGeological map of the study area (modified after EGPC and Conoco Coral49) (generated using ArcMap version 10.8 https://desktop.arcgis.com/en/arcmap/latest/get-started/setup/arcgis-desktop-system-requirements.htm ).\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/12f06fd19191f183adac9a04.png"},{"id":86495744,"identity":"0221a5f7-1a74-4ff0-a5f3-12eae09f468b","added_by":"auto","created_at":"2025-07-11 10:02:51","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":263477,"visible":true,"origin":"","legend":"\u003cp\u003eRTP aeromagnetic map of the study area (a) Bouguer gravity map (b) (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/). \u0026nbsp;\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/0cd2954df2e909f438cc4500.png"},{"id":86495742,"identity":"72ab4669-2806-4421-8eea-2df8f9a48a88","added_by":"auto","created_at":"2025-07-11 10:02:51","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":92856,"visible":true,"origin":"","legend":"\u003cp\u003eSubsurface lithology of\u003cstrong\u003e \u003c/strong\u003eborehole G-028a as an example of boreholes in the study area\u003c/p\u003e\n\u003cp\u003e(compiled from Egypt phosphate company) (generated using Strater version 5).\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/e86b51808c59714a1dd4c53f.png"},{"id":86495749,"identity":"fd8a5535-66a1-4c98-bef1-723b4256a6f1","added_by":"auto","created_at":"2025-07-11 10:02:51","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":565631,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart illustrating the main processes of analysis that will be performed on the RTP aeromagnetic and Bouguer gravity data of the study area.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/f5000892fe4e7455f17f84c0.png"},{"id":86495753,"identity":"7c4b82c9-4ce3-4495-a7b1-ee94d587beee","added_by":"auto","created_at":"2025-07-11 10:02:51","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":275486,"visible":true,"origin":"","legend":"\u003cp\u003eLow pass filter of the RTP aeromagnetic map (a) and of the Bouguer gravity map (b) (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/ ). \u0026nbsp;\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/1c5bb980e42b8bc7ea56d527.png"},{"id":86495747,"identity":"5b0092c9-fb24-41bd-af75-a17ae8d006b0","added_by":"auto","created_at":"2025-07-11 10:02:51","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":319244,"visible":true,"origin":"","legend":"\u003cp\u003eHigh pass filter of the RTP aeromagnetic map (a) and of the Bouguer gravity map (b) (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/ ).\u0026nbsp;\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/3228850840a5b4544d571e50.png"},{"id":86495746,"identity":"043cd503-7799-4ea0-991c-33521724ee27","added_by":"auto","created_at":"2025-07-11 10:02:51","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":398315,"visible":true,"origin":"","legend":"\u003cp\u003eFirst vertical derivative of the RTP aeromagnetic map (a) and of the Bouguer gravity map (b), the black lines are the zero contours (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/).\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/62457819a7f006af7779a987.png"},{"id":86496545,"identity":"07d0bba6-8093-4303-8ce6-5372b3416961","added_by":"auto","created_at":"2025-07-11 10:10:51","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":404802,"visible":true,"origin":"","legend":"\u003cp\u003eTilt derivative filter of the RTP aeromagnetic map (a) and of the Bouguer gravity map (b), the black lines are the zero contours (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/).\u0026nbsp;\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/871e11fe77e9c23dcbf4239a.png"},{"id":86497911,"identity":"b1899e5a-ebfb-444a-b0a5-1b54454c1199","added_by":"auto","created_at":"2025-07-11 10:26:51","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":381233,"visible":true,"origin":"","legend":"\u003cp\u003eAnalytical signal of the RTP aeromagnetic map (a) and of the Bouguer gravity map (b) (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/). \u0026nbsp;\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/a15d81fb50e541910a5b1d8f.png"},{"id":86497037,"identity":"42037410-9839-401b-9cf8-d580cffc2932","added_by":"auto","created_at":"2025-07-11 10:18:51","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":506212,"visible":true,"origin":"","legend":"\u003cp\u003eThe five profiles which are selected for 2D gravity and magnetic modeling along the RTP aeromagnetic map (a) and the Bouguer gravity map (b) (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/). \u0026nbsp;\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/eb2ad451dcdac24c1db03e66.png"},{"id":86497038,"identity":"a681e2bf-785f-4ffd-8736-e3ee1fc00fb5","added_by":"auto","created_at":"2025-07-11 10:18:51","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":579464,"visible":true,"origin":"","legend":"\u003cp\u003e2D Gravity and magnetic modelling along A-A` profile (a), 2D Gravity and magnetic modelling along B-B` profile (b), where D= Density of rock (g/cc), S= Magnetic susceptibility (SI) (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/). \u0026nbsp;\u003c/p\u003e","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/0d5c3793dbf60dc07f4d706f.png"},{"id":86495769,"identity":"8c718c42-c175-4cef-9ac5-5bd03586d512","added_by":"auto","created_at":"2025-07-11 10:02:52","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":686093,"visible":true,"origin":"","legend":"\u003cp\u003e2D Gravity and magnetic modelling along C-C` profile (c), 2D Gravity and magnetic modelling along D-D` profile (d), 2D Gravity and magnetic modelling along E-E` profile (e), where D= Density of rock (g/cc), S= Magnetic susceptibility (SI) (generated using Geosoft Oasis Montaj version 8.4 https://community.seequent.com/).\u003c/p\u003e","description":"","filename":"floatimage13.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/3548bca3f01e5050c77c28ef.png"},{"id":86497912,"identity":"9df1b5d8-a574-4df4-8d18-4a107cc4b8fb","added_by":"auto","created_at":"2025-07-11 10:26:51","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":289728,"visible":true,"origin":"","legend":"\u003cp\u003eStructure contour map of the basement surface\u003cstrong\u003e \u003c/strong\u003e(generated using Golden Surfer Software version15).\u003c/p\u003e","description":"","filename":"floatimage14.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/9620f4061c0894b007cb637d.png"},{"id":86496550,"identity":"9a8e6e40-116a-4aa1-b0fa-7f0e8fa9144c","added_by":"auto","created_at":"2025-07-11 10:10:51","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":333213,"visible":true,"origin":"","legend":"\u003cp\u003eStructure contour map of the top Nubian sandstone surface (generated using Golden Surfer Software version 15).\u003c/p\u003e","description":"","filename":"floatimage15.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/e5d09dff3acc53a9f3c2d38f.png"},{"id":86497042,"identity":"0c50b169-f114-4e6c-a12b-cfc77dcc2262","added_by":"auto","created_at":"2025-07-11 10:18:52","extension":"png","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":345185,"visible":true,"origin":"","legend":"\u003cp\u003eIsopach map of phosphatic rocks (generated using Golden Surfer Software version15).\u003c/p\u003e","description":"","filename":"floatimage16.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/c83877750b07abae9bfe559d.png"},{"id":86495800,"identity":"c942ae96-fed4-4eb1-9d2a-0635c6248280","added_by":"auto","created_at":"2025-07-11 10:02:53","extension":"png","order_by":17,"title":"Figure 17","display":"","copyAsset":false,"role":"figure","size":640595,"visible":true,"origin":"","legend":"\u003cp\u003eCombination of structure contour map of the basement surface, structure contour map of the top Nubian sandstone surface and thickness map of the phosphatic rocks with the 3D view of the Abu Tartur plateau (generated using Golden Surfer Software version15).\u003c/p\u003e","description":"","filename":"floatimage17.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/164e8b36be9673ed5b828071.png"},{"id":86495798,"identity":"3c9933a0-eb28-4a08-8c0d-7f37fafea489","added_by":"auto","created_at":"2025-07-11 10:02:53","extension":"png","order_by":18,"title":"Figure 18","display":"","copyAsset":false,"role":"figure","size":316180,"visible":true,"origin":"","legend":"\u003cp\u003eStructure lineaments traced from: the RTP aeromagnetic map (a), the Bouguer gravity map (b), the regional map of RTP aeromagnetic data (c) and the regional map of Bouguer gravity data (d) (generated using Rockware Software version 15 https://www.rockware.com/).\u003c/p\u003e","description":"","filename":"floatimage18.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/ac552f79ad18c6b17b21df63.png"},{"id":86495773,"identity":"fb770cbb-7f4b-4a51-87af-f1c21e79a4cc","added_by":"auto","created_at":"2025-07-11 10:02:52","extension":"png","order_by":19,"title":"Figure 19","display":"","copyAsset":false,"role":"figure","size":497191,"visible":true,"origin":"","legend":"\u003cp\u003eStructure lineaments traced from: the residual map of RTP aeromagnetic data (a), the residual map of Bouguer gravity data (b), the FVD map of RTP aeromagnetic data (c), the FVD map of Bouguer gravity data (d), the TDR map of RTP aeromagnetic data (e) and the TDR map of Bouguer gravity data (f) (generated using Rockware Software version15 https://www.rockware.com/).\u003c/p\u003e","description":"","filename":"floatimage19.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/a02013f1d237a08bb6c977db.png"},{"id":86496566,"identity":"6e96f5e4-a0a0-4898-9b31-48aaf5277d3d","added_by":"auto","created_at":"2025-07-11 10:10:52","extension":"png","order_by":20,"title":"Figure 20","display":"","copyAsset":false,"role":"figure","size":161024,"visible":true,"origin":"","legend":"\u003cp\u003eStructure lineaments traced from the AS map of RTP aeromagnetic data (a) and from the AS map of Bouguer gravity data (b) (generated using Rockware Software version15 https://www.rockware.com/).\u003c/p\u003e","description":"","filename":"floatimage20.png","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/8a1657ed1fd56c416f76c987.png"},{"id":107927660,"identity":"ce7d2350-1757-4572-b179-b4d822675fe9","added_by":"auto","created_at":"2026-04-27 16:00:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":23665327,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6981993/v1/d3b5b801-f5c4-494f-b40f-36aa52b82478.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Geophysical Characterization of Subsurface Structures for Optimal Planning in the Abu Tartur Phosphate Mine","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eOptimal mine planning is essential for sustainable mining practices, as it mitigates the environmental and economic impacts of resource extraction \u003csup\u003e\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Through advanced subsurface characterization and strategic operational design, mine planning minimizes costs and waste, reduces environmental damage, and extends the lifespan of mineral reserves \u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. This approach conserves resources and promotes the long-term viability of mining, aligning with sustainable development principles \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. Phosphate ore, a non-renewable but essential resource for agriculture and industry, exemplifies this need \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. As the primary component of phosphate fertilizers, it plays a vital role in global food production by enriching soil and increasing crop yields \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e,\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e Phosphate is also critical for animal feed, detergents, and various industrial chemicals \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. Therefore, extracting and utilizing phosphate more efficiently is essential for addressing global food security while minimizing the environmental impact of mining \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eAs one of the world's significant phosphate reserves, the Abu Tartur Phosphate Mine (ATPM) in Egypt represents a vital resource for the nation's economic and industrial development \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. However, the ATPM has faced significant operational challenges, culminating in the recent closure of its subsurface mining operations \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. These challenges, primarily due to insufficient geological understanding and unrecognized subsurface structures, underscore the urgent need for improved methods for subsurface characterization to support effective mine planning and sustainable resource extraction \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. The geological complexity of the ATPM region, characterized by concealed faults and variable thickness of phosphate layers, has historically hindered efficient mining operations \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. Earlier efforts to map the subsurface geology relied on incomplete or imprecise datasets, leading to suboptimal placement of mining operations \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. For example, the closure of the subsurface ATPM has been linked to an inadequate understanding of the fault systems and stratigraphic variations, which obscured the distribution of economically viable phosphate beds. This misallocation of mining resources not only increased operational costs but also contributed to the premature abandonment of potentially productive areas.\u003c/p\u003e\u003cp\u003ePrevious studies addressing the challenges of underground mine closures have predominantly focused on geotechnical aspects, such as optimizing extraction panel widths \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e, designing support systems \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e, and calculating suitable reinforcement strategies \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. While these approaches provide valuable insights into the structural stability of underground mines, they often overlook the critical role of comprehensive geological assessments in addressing operational failures. At the ATPM, the decision to abandon underground mining in Favor of surface mining behind the plateau has left substantial phosphate reserves untapped, raising concerns about resource wastage and economic inefficiency. This highlights a significant gap in the literature: the lack of comprehensive geological analyses to identify and characterize subsurface structures that may offer viable solutions to sustain mining operations. Addressing this gap is essential to exploring alternative strategies that optimize resource utilization while ensuring economic and environmental sustainability.\u003c/p\u003e\u003cp\u003eGeophysical methods have proven to be powerful tools for subsurface exploration, offering non-invasive means to delineate geological structures and characterize mineral deposits \u003csup\u003e\u003cspan additionalcitationids=\"CR19 CR20\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. These techniques leverage the physical properties of rocks and their constituent minerals to investigate features of subsurface, playing a crucial role in mineral exploration by identifying and delineating the extent, boundaries, quantity, and quality of deposits before mining operations commence \u003csup\u003e\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Among these methods, the magnetic technique is widely used due to its effectiveness in detecting and mapping subsurface anomalies \u003csup\u003e\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. For example, in Morocco's A\u0026iuml;n Beida mine, magnetic surveys successfully delineated manganese-rich zones associated with ferruginous minerals \u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e, while in Ibadan, Nigeria, high resolution aeromagnetic data revealed potential mineral deposits using advanced processing techniques particularly, Derivative and Analytic Signal Amplitude \u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. Similarly, gravity methods have been employed in gold exploration in South Africa \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e, \u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e and in the identification of chromite\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e, \u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e, iron \u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e, manganese\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e, copper sulphide ores \u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e,\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e, and coal deposits \u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e,\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e, further highlighting their versatility. While single geophysical methods have yielded significant insights, the complexity of ore-bearing formations often requires a multi-disciplinary approach \u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e. Combining magnetic data with other geophysical methods, such as seismic and gravity techniques, enhances the understanding of underground geological structures and provides a more comprehensive view of potential zones of mineral accumulation. For instance, in Sefwi Belt of Ghana, integration of gravity and magnetic data were successfully delineated zones of gold mineralization, mapping lithological units and structural features with high precision \u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. Such integrations not only improve exploration accuracy but also reduce the risks and costs associated with drilling and direct exploration methods. Despite their proven success, the integration of Bouguer gravity and aeromagnetic data for systematic subsurface characterization had not been extensively studied in ATPM region. This lack of exploration leaves critical knowledge gaps regarding subsurface structures, limiting the potential for optimizing phosphate resource extraction. Addressing this gap through integrated geophysical techniques offers an opportunity to develop a more comprehensive understanding of the region\u0026rsquo;s geology, guiding future mining operations towards sustainability and economic feasibility.\u003c/p\u003e\u003cp\u003eThe present study aims to address these gaps by employing a comprehensive geophysical approach to characterize the subsurface structures of the ATPM region. Using Reduced to the Pole (RTP) aeromagnetic and Bouguer gravity anomaly data, along with advanced filtering techniques, this research identifies and models the key geological features controlling phosphate layer distribution. Structure contour maps and thickness maps generated from 2D modelling provide a detailed understanding of the subsurface environment, enabling the identification of optimal zones for future mining operations. This research contributes to the field by combining geophysical techniques to provide a holistic understanding of the ATPM region's geology. By pinpointing the structural controls on phosphate bed distribution, it highlights areas with higher economic potential and underscores the limitations of previous mine placement strategies. The results of this study not only have been helpful for ATPM but also offer a methodological framework for similar mining challenges worldwide, where subsurface geological complexities hinder resource extraction.\u003c/p\u003e"},{"header":"2. Location and Geological setting of the study area","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Location of study area\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003ePhosphate deposits are distributed in several locations in Egypt along the phosphate belt. The investigated area is part of the Western Desert in Egypt, including the Abu Tartur Plateau that occurs at the western escarpment of the El-Kharga Oasis (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). It lies between latitudes 25˚10 ̀and 25˚50 ̀ N and longitudes 29˚25 ̀and 30˚20 ̀ E.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 General geology\u003c/h2\u003e\u003cp\u003eAccording to a geological map covering Egypt's middle latitudes, the phosphorite deposits are primarily found in Hanmraween area (Eastern Desert), in Sebaiya area (along the Nile Valley), and in the Western Desert in the Abu Tartur area \u003csup\u003e\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. Abu Tartur phosphate deposit, which is thought to be the thickest deposit in Egypt, covers an area of roughly 1200 km\u0026sup2;. The main region is located between El-Kharga Oasis in the east and El-Dakhla Oasis in the west includes Abu Tartur plateau \u003csup\u003e\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e. Most of the sedimentary rocks of the Abu Tartur Plateau region are Pre-Maastrichtian to Quaternary in origin. From oldest to youngest, the Upper Cretaceous Lower Tertiary formations that make up the plateau's sedimentary sequence, especially on the eastern side (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), are Taref Nubia sandstone formation, Quseir shale formation, Duwi formation (phosphorite), Dakhla shale formation, and Kurkur limestone formation \u003csup\u003e\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e. In Egypt, the Duwi Formation which is constitutes the phosphatic rocks are of Late Cretaceous marine transgression that is overlain conformably by the deep marine shales and marls of the mid-Maastrichtian Dakhla Formation and unconformably overlies the fluvial shale sequence of the mid-Campanian Quseir Formation. The phosphate beds are interbedded with glauconites, argillaceous limestone, and black shale. The economic phosphate bed is at the base of the Duwi formation \u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Structural setting\u003c/h2\u003e\u003cp\u003eThe Cretaceous and Lower Tertiary depositional environments in southern Egypt, especially Abu Tartur Plateau, is studied and discussed, based on a combination of paleontological and sedimentological studies, that repeated sea level fluctuations and large scale rejuvenation of pre-existing fault systems determined the Cretaceous to Early Tertiary evolutionary history of the depositional environments of southern Egypt \u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e. The Dakhla (quite near Abu Tartur) and Assiut Basins formed in Central Egypt in the Late Jurassic or Early Cretaceous, marking the beginning of the progressive subsidence of large intracratonic depressions caused by these fault systems. Sea level variations and synsedimentary tectonism governed the transgressions and regressions that filled these depressions with sediments of continental and marine origin. Typical stable shelf tectonics is responsible for the structural components of El-Kharga-Dakhla stretch. The block movements in the basement are indicated by faults and, to a lesser extent, large gentle folds that are reflected on the surface. The thickness and lithology of the sedimentary cover, especially in its southern regions, most likely determine the kind and severity of the tectonics and deformations. The predominant tectonic characteristic is faults, which are more persistent and denser. The only area in the El-Kharga-Dakhla stretch in which crystalline basement outcrops with a thin sedimentary layer and noticeable basement rock up-arching can be observed is the southern portion of the Kharga Oasis. However, the broad warping and undulations is more noticeable in the west and northwest of El-Kharga, as Abu Tartur and El-Dakhla areas \u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Methodology and data processing","content":"\u003cp\u003eIntegration between gravity and magnetic methods is the most effective geophysical technique, which can disturbances in the Earth's gravity and magnetic fields to determine the density and magnetic susceptibility of rocks which reflecting the subsurface structures. In the present study the gravity and magnetic data were used to study the general picture of the predominant subsurface structures of the study area. The data were available in the form of reduced to the pole (RTP) aeromagnetic data compiled by the Egyptian General Petroleum Corporation EGPC (1989), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea and in form of Bouguer gravity data downloaded from the website, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://bgi.obs-mip.fr/\u003c/span\u003e\u003cspan address=\"https://bgi.obs-mip.fr/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. The data was prepared in a contour map as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb. The subsurface real lithology was recognised from the deep wells in or close to the study area as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eAnalysis and interpretation of RTP aeromagnetic and Bouguer gravity data were carried out through the following flowchart (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Data processing\u003c/h2\u003e\u003cp\u003eBoth RTP aeromagnetic and Bouguer gravity data should be filtered to condition the data set which making it easier to interpret the significance of gravity and magnetic anomalies in terms of geological features. In the present study, different filters will be applied on the Bouguer gravity and RTP aeromagnetic data. These filters can summarize as follows:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eThe Fast Fourier Transform (FFT) was applied to the data for producing the energy spectrum curve. From the resulted curve, the depths to the shallow and deep sources \u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe (regional) low pass filter highlights deep, high amplitude sources by suppressing small anomalies and high frequency noise. As a result, the anomalies appear broader and less sharp than those on the Bouguer anomaly and RTP aeromagnetic maps, while the regional field itself exhibits an overall smooth trend pattern. The (residual) high pass filter shows the high frequency and short wavelength anomalies of limited aerial extension that emphasize the shallow seated causative bodies \u003csup\u003e\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e,\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe first vertical derivative filter measures the rate of change in the vertical direction of the gravity/magnetic field. The first vertical derivative also be positive over the source, zero over the edge, and negative outside of a vertical sided source \u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe tilt derivative filter is the generalized local phase; it was applied to determine the vertical and inclined contacts and/or structure lines and used for mapping shallow basement structures and mineral exploration targets. On the other hand, tilt derivative has anomaly zero crossings located close to the edges of structures. TDR was estimated by dividing the vertical derivative by the total horizontal derivative as given in Eq.\u0026nbsp;1 \u003csup\u003e54,55\u003c/sup\u003e.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:TDR=arctan\\left(\\frac{VDr}{THDR}\\right)\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(1\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eThe analytic signal (AS) method or, total gradient method used for defining the edges (boundaries) of geologically anomalous magnetization or density distributions \u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e. The analytic signal technique was discussed elsewhere by \u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e,\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e,\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e\u003c/sup\u003e as the square root of the squared sum of the vertical and horizontal derivatives of the magnetic field as given in Eq.\u0026nbsp;2.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\:Asig=\\sqrt{d{x}^{2}+d{y}^{2}+d{z}^{2}}\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(2\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eAll applied filters were carried out by using Geosoft Oasis Montaj version 8.4 \u003csup\u003e59\u003c/sup\u003e. In addition to the filters that were applied to the gravity and RTP aeromagnetic data, 2D gravity and magnetic modelling were applied. These models were applied to show the subsurface geologic sequence in the study area along definite directions. The sequence shows the subsurface geologic layers from the surface to the basement rocks. The subsurface structures prevailing in the study area also can be outlined from the model. The modelling process was carried out by applying an interactive modelling package running on GM-SYS through Geosoft Oasis Montaj version 8.4 \u003csup\u003e59\u003c/sup\u003e.\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Results and discussion","content":"\u003cp\u003eThe qualitative and quantitative interpretation of the Bouguer gravity and Aeromagnetic (RTP) data covering the study area are discussed below\u003c/p\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e4.1 Qualitative interpretation\u003c/h2\u003e\u003cp\u003eThe qualitative interpretation of both gravity and magnetic data includes inspection of the shape, magnitude, amplitude and linearity of both gravity and magnetic anomalies in Bouguer gravity and RTP aeromagnetic maps, first vertical derivative, analytical signal, and tilt derivative maps. The gravity and magnetic lineaments that are corresponding to linear structures are also traced from all mentioned maps and presented on rose diagrams.\u003c/p\u003e\u003cdiv id=\"Sec10\" class=\"Section3\"\u003e\u003ch2\u003e4.1.1 RTP aeromagnetic and Bouguer gravity maps\u003c/h2\u003e\u003cp\u003eThe RTP aeromagnetic map of the study area (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea) shows the magnitudes of the magnetic anomalies vary from- 152.9 to +\u0026thinsp;103.7 nT. This great variation in the magnitude of magnetic anomalies is pointing to the area is highly affected by different structure sets. The central and southeastern parts of the area show lower magnitudes ranging from \u0026minus;\u0026thinsp;19.9 to -152.9 nT, which indicates that this area is uplifted with occurrence of granite basement rocks, which have low magnetic susceptibility in compared with the surrounding rocks. Whereas the northern part shows a high magnitude magnetic anomaly pointing to a magnetic source of high magnetic susceptibility in compared with other areas.\u003c/p\u003e\u003cp\u003eThe Bouguer gravity map of the study area (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb) shows major parts of the area are covered by positive gravity anomalies with values changing from 3.22 to 34.46 mGal. The central part of the study area, which includes Abu Tartur plateau, has maximum positive gravity values. This indicates that Abu Tartur plateau is an uplifted plateau, whereas the southwestern part, which has negative gravity values ranging from \u0026minus;\u0026thinsp;6.28 to -19.18 mGal, is downfaulted blocks.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section3\"\u003e\u003ch2\u003e4.1.2 Reginal and residual maps of both RTP and Bouguer data\u003c/h2\u003e\u003cp\u003eThe high (residual) and low (regional) pass filters were carried out with a cutoff of 0.025 cycle/km. The regional magnetic and gravity anomalies are given in Figs.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb. from these figures, it can see most of the magnetic and gravity anomalies are circular to oval, pointing circular to subcircular geologic features. The linear regional magnetic and gravity anomalies in W-E and NW-SE directions, indicating deep seated regional subsurface structures prevailing in both northern and central parts of the area.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe residual anomaly maps of RTP aeromagnetic and Bouguer gravity are given in Figs.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea and \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb. The residual RTP anomalies are of positive and negative magnitudes with circular to semi-circular shapes (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea). These anomalies are aligned mostly in W-E and NW-SE directions, indicating shallow geologic features and/or structures extending in the same directions. These two structure directions were recorded by different authors on the surface. The Bouguer gravity anomalies (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb) show well defined W-E and WNW-ESE extensions. The W-E extension pointing to predominant structure lineaments that were recorded by different authors as W-E strike slip faults. This fault trends are originated from the basement rocks and extended upward in the sedimentary cover.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section3\"\u003e\u003ch2\u003e4.1.3 FVD, TDR and AS of both RTP aeromagnetic and Bouguer gravity data\u003c/h2\u003e\u003cp\u003eThe FVD is an effective tool to enhance the small and weak anomalies that reflect near surface geologic features and/or structures. Also, it is used to delineate lithologic contacts due to contrasts in susceptibility and density (Figs.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea and \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb). The first vertical derivative map of the RTP aeromagnetic map (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea) shows that, the magnitudes of the magnetic anomalies are generally vary from \u0026minus;\u0026thinsp;0.028 to +\u0026thinsp;0.024 nT/m. Local anomalies of short wavelengths indicating shallow sources; however, zero contours are reflecting contacts or faults. From the map the main directions of the magnetized sources and lithologic as well as structure contacts are extending in the NNE-SSW, ENE-WSW, and W-E directions. The first vertical derivative map of the Bouguer gravity data (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb) reveals that the magnitudes of the anomalies are alternating positive and negative with values reach up to +\u0026thinsp;0.003 mGal/m and \u0026minus;\u0026thinsp;0.003 mGal/m, respectively. From the distribution of zero contour lines, the major lithologic contacts and/or structure lines are extending mainly in the ENE-WSW and W-E directions.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe tilt derivative filter (TDR) was applied on both RTP aeromagnetic and Bouguer gravity data to determine the vertical and inclined contacts and/or structure lines. The zero contours are indicating the edges of the causative bodies which may be structure or lithologic contacts. The resulting maps are shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ea and \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003eb, respectively. The TDR map of the RTP aeromagnetic data (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ea) shows that the radians of the anomalies vary from \u0026minus;\u0026thinsp;1.5 to +\u0026thinsp;1.3 radians. The tilt derivative anomalies are similar to the first vertical derivative anomalies in the shape and trends of the major structure. The TDR map of the Bouguer gravity data (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003eb), shows that the TDR values range between \u0026minus;\u0026thinsp;1.3 and +\u0026thinsp;1.3 radians. The TDR anomalies of the RTP aeromagnetic data are generally local anomalies with W-E extensions; however, the TDR of the Bouguer gravity data are three major anomalies extending nearly W-E. The local TDR anomalies of the RTP aeromagnetic data are pointing to local variation in the magnetic susceptibility within the basement rocks; however, the major anomalies on the TDR of the Bouguer gravity data are mainly extending in W-E direction pointing to major structure may originated from basement rocks and extended upward within the sedimentary cover.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe analytical signal (AS) maps of both RTP aeromagnetic and Bouguer gravity data are shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ea and \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eb. Generally, analytical signal maxima occur directly over faults and contacts. The analytical signal technique was applied to define the edges (boundaries) of bodies that are considered as basins or uplifts in the study area. From the AS map of the RTP aeromagnetic data (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003ea), the analytical signal values range from 0.0037 to 0.0377 nT. The maximum values are observed at the central and northern parts, which indicate that these parts of study area suffer from complicated structures; however, the minimum values are noticed at the western and southern parts, indicating to structure\u0026rsquo;s simplicity in those parts. The AS map of the Bouguer gravity data map (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003eb) shows that the analytical signal values range from 0.0005 to 0.0041 mGal. The northern part of the study area is characterized by low analytical signal anomalies indicating structural simplicity. However, the southern and central parts show high AS anomalies indicating complex structures.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e4.2 Quantitative interpretation\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe quantitative interpretation in the present study was emphasized on 2D gravity and magnetic modelling utilizing the GM-SYS software. From the modelling results, the top surface of the Nubian sandstone layer and the basement surface were well defined and continues all over all models. These surfaces were marked and their depth related to the main sea level was exported as data XYZ files via the software. Furthermore, the top and bottom surfaces of the phosphatic rocks were also marked and exported in data XYZ files. From these files, the true thickness of the phosphatic rocks was estimated. Accordingly, a) depth or structure contour maps were prepared for the top surface of the Nubian Sandstone and basement surface, and b) an isopach map for phosphatic rocks. These maps were generated by utilizing Golden Surfer Software version15 \u003csup\u003e60\u003c/sup\u003e.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec14\" class=\"Section3\"\u003e\u003ch2\u003e4.2.1 2D gravity and magnetic modelling\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe 2D modelling was started by outlining the most important anomalies on the Bouguer gravity and RTP aeromagnetic maps. Such anomalies are corresponding to the predominant subsurface geologic features. About five profiles along definite lines crossing the main anomalies and extending in different directions to cover most of the study area. The technical steps of the modelling through GM-SYS of Oasis Montaj version 8.4 were as follows:\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eImporting the data files, which include the coordinates and gravity or RTP aeromagnetic values from the gridded maps. The data was in XYZ format; X is the longitude, Y is the latitude, and Z is the Bouguer gravity or RTP aeromagnetic values in mGal and nT, respectively. The XY long/lat coordinates were converted into the UTM system by applying UTM projection Datum WGS1984, ellipsoid WGS 84, and Zone 35 N.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eGridding data using Oasis Montaj, which provides seven different gridding algorithms to produce a grid. The gridded data is taken as input for producing a contour map. This map represents the aerial distribution of both Bouguer and RTP aeromagnetic anomalies, which are reflecting the subsurface geologic features and structures.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eThe forward modelling was started by entering initial parameters of the subsurface sequence including density and magnetic susceptibility as well as depths to the boundaries which separate the expected subsurface layers or rock formations. Based on the entered initial parameters the program calculates the theoretical Bouguer gravity and RTP aeromagnetic values. After performing the calculation, the calculated values are compared to the observed one. Different adjustments through several iterations were carried out on the initial parameters to get the best fit between the observed and the calculated values. The adjustments and iterations were continued until get low RMS values and logic subsurface model.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cdiv id=\"Sec15\" class=\"Section4\"\u003e\u003ch2\u003e4.2.1.1 Initial parameters for the 2D modelling\u003c/h2\u003e\u003cp\u003eFor 2D gravity modelling, the initial parameters were the expected subsurface sedimentary sequences over the basement rocks. The expected subsurface sequence was collected from the published literature and the deep wells in the study area. For example, the Malab El-kheil well with depth to the basement rocks of 598 below sea level and the Ph2 well with a depth to the basement rocks of 755 m below sea level (Wells No. 8 and 10 respectively, in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e). The wells which not reached to the basement rocks such as those obtained from phosphate Egypt company, the depth to the basement was extrapolated based on the published work such as \u003csup\u003e\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e\u003c/sup\u003e. The sequence over the basement rocks is started by Nubian sandstone (Nubian formation) with thickness more than 300 m \u003csup\u003e\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e,\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e\u003c/sup\u003e, followed by variegated shale (Quseir formation) with thickness ranging from 100 to 225 m \u003csup\u003e\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e\u003c/sup\u003e, followed by Duwi formation which composed from phosphatic rocks and black shale with thickness varying from 20 to 30 m, the Duwi formation is followed by Dakhla shale (Dakhla formation) with thickness ranging from 100 to 135 m, followed by Limestone belonging to (KurKur formation) with thickness varying from 25 to 100 m \u003csup\u003e\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e,\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e\u003c/sup\u003e. The average density of the mentioned rock types was obtained from published literatures such as \u003csup\u003e\u003cspan additionalcitationids=\"CR66 CR67\" citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e\u003c/sup\u003e and textbooks \u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e,\u003cspan additionalcitationids=\"CR70\" citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e\u003c/sup\u003e. Accordingly, the average densities of the subsurface sequence in the study area can be summarized as follows: Limestone (2.5\u0026ndash;2.7 g/cm\u0026sup3;), Dakhla shale (1.77\u0026ndash;2.6 g/cm\u0026sup3;), Phosphatic rocks (1.52\u0026ndash;2.97 g/cm\u0026sup3;), Variegated shale (2.63\u0026ndash;2.65 g/cm\u0026sup3;), Nubian sandstone (2.65\u0026ndash;2.67 g/cm\u0026sup3;) and Basement rocks with density ranging from 2.52 to 3.45 g/cm\u0026sup3;.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eFor 2D magnetic modelling, the initial parameters were the magnetic susceptibility of the basement rocks and the overlying sedimentary cover. The magnetic susceptibility of the basement rocks in and around the study area is ranging from 0.001 to 0.0058 cgs units \u003csup\u003e\u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e72\u003c/span\u003e\u003c/sup\u003e which is equivalent to 0.013\u0026ndash;0.073 in SI units and the magnetic susceptibility of the sedimentary cover is negligible.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe five profiles which were selected for 2D modelling are shown on both RTP aeromagnetic and Bouguer maps (Figs.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003ea and \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003eb). The profiles were nominated, A-\u0026Agrave;, B-B ̀, C-C ̀, D-D ̀ and E-E ̀. The Profile A-\u0026Agrave; is with length 64.006 km, Profile B-B ̀ is with length 85.041 km, Profile C-C ̀ is with length 85.714 km, Profile D-D ̀ is with length 84.936 km, and Profile E-E ̀ is with length 776.1624 km.\u003c/p\u003e\u003cp\u003eFigures \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e and \u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e show the 2D gravity and magnetic modeling and the obtained subsurface geologic models. The best fit between the calculated and observed gravity and magnetic values were obtained by following the RMS values through the GM-SYS of Oasis Montaj version 8.4. The accepted RMS values for all modeled profiles ranged between 3.549 and 8.014%. This range of RMS values falls within the commonly accepted range for RMS values, which is generally below 15%. The acceptance of the models beside the RMS values was the correspondence of the obtained models with the real subsurface sequence in the study area. Furthermore, the obtained models were controlled by the subsurface data of deep wells drilled in the study area.\u003c/p\u003e\u003cp\u003eFrom the interpretation of five profiles and the corresponding 2D gravity and magnetic modelling, A-A`, B-B`, C-C`, D-D`, and E-E` Which extend SW to NE, SE to NW, WNW to ESE, SE to NW, and SSW to NNE, respectively, and pass through the available wells in the study area, the subsurface sequence can be summarized as follows:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eThe basement rocks are situated at depths range from 138 to 798 m below sea level with average density ranges from 2.6 to 3.5 g/cm\u0026sup3; and magnetic susceptibility vary from 0.048 to 0.07 SI units. These remarkable variations in both density and magnetic susceptibility indicate lateral variations in mineral composition of the basement rocks that may reflect also lithologic contacts between different basement rock types.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe Nubian sandstone layer, which is defined as Nubian Sandstone Formation in literatures has an average thickness ranges from 90 to 525.53 m with average density of 2.66 g/cm\u0026sup3;. This great variation in the thickness may indicate that this formation is highly affected by faulting.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe variegated shale layer, which is defined as Quseir Formation in literatures, has an average thickness ranges from 58.76 to 374.13 m with average density of 2.1 g/cm\u0026sup3;. This formation appeared on the models as continuous shale layer and silty shale lenses with density 2.13 g/cm\u0026sup3; in some places. The lenses have average thickness range from 498.86 to 765.524m. These high values of thickness may be due to that the silty shale lenses deposited in deep lagoon or lakes environment, and with density 2.13 g/cm\u0026sup3;.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe Dakhla shale layer, which is defined as Dakhla Formation in the literatures, is observed with average density 1.8 g/cm\u0026sup3; as a continuous layer along the D-D` model by thickness ranges from 30.61 to 510.20 m. Whereas, appeared as separated blocks along A-A`, B-B`, C-C`, and E-E` models with average thickness varies from 201.5 to 396.15 m. The blocks are predominant at the parts which may be affected by faulting and weathering.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe limestone layer, which is defined as Kurkur Formation in the literatures, with average density 2.7 g/cm\u0026sup3; has appeared as capping the sedimentary sequence, and hence its actual thickness is not estimated.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe main objective of the present study was targeted to the mode of occurrence of the phosphatic rocks, the parts of the models which have the phosphatic rocks are zoomed out and plotted below the models. The phosphatic rocks are defined as Duwi Formation in the literatures. From the zoom out parts, the phosphatic rocks with average density 2 g/cm\u0026sup3; are observed as a continuous layer along A-A` and D-D` models with average thickness ranges from 1.75 to 19.9 m and as a disconnected layer along B-B`, C-C`, and E-E` models with average thickness varies from 1.9 to 23.46 m. This great thickness variations and disconnection in the phosphatic rocks may be due faults that are predominant in the study area.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eLateral thickness variation of subsurface sequence from the Nubian sandstone at the bottom to the Kurkur Formation at the top may indicate that all the sequence is affected by structures originating from the basement rocks and extending upward in the sedimentary cover.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section4\"\u003e\u003ch2\u003e4.2.1.2 Depth or structure contour map of the basement surface\u003c/h2\u003e\u003cp\u003eFrom the prepared map of the basement surface in the study area (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e), the main structures are two syncline folds located at the northern and eastern parts of the study area. These syncline folds are of asymmetrical double plunging with an axis extending NE-SW direction. Another symmetrical plunging syncline fold with an axis extending NE-SW is observed at the northwest part of the study area. At the western part, the contours show a basin structure. There are four anticlines located in the northern, eastern, western, and southern parts of the study area. The anticline fold in the northern part is asymmetrical, plunging with an axis extending NE-SW direction. The anticline fold in the eastern part is symmetrical plunging with an axis extending WNW-ESE. The anticline fold in the southeastern part is asymmetrical plunging with an axis extending WNW-ESE. The anticline fold in the western part is symmetrical plunging with an axis extending NNE-SSW. Two dextral strike slip faults are also noticed; the first one is in the northern part of the study area extending WNW-ESE and another one is in the southern part extending W-E.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section4\"\u003e\u003ch2\u003e4.2.1.3 Depth or Structure contour map of the top Nubian sandstone layer\u003c/h2\u003e\u003cp\u003eFrom the structure contour map of the top Nubian sand surface in the study area (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e), the main structures are five synclines located in the northern, eastern, western, southeastern, and southern parts of the study area. The syncline fold at the northern part is asymmetrical double plunging with an axis extending NE-SW. The syncline fold at the western part of the study is asymmetrical double plunging with an axis extending NNW-SSE. The syncline fold at the eastern part is symmetrical double plunging with an axis extending NNW-SSE. The syncline fold at the southeastern part is asymmetrical double plunging with an axis extending W-E. The syncline fold at the southern part of the study area is asymmetrical plunging with an axis extending WNW-ESE. Two anticline folds are defined in the northern and southern parts of the study area. The anticline fold at the northern part is asymmetrical plunging with an axis extending NE-SW. The anticline fold at the southeastern part is asymmetrical plunging with an axis extending NW-SE. Six normal faults are observed at the middle part of the study area, bounding Abu Tartur plateau and extending NNW-SSE, NE-SW, and NW-SE. The downthrows of these faults are due to the lowlands outside of the plateau. Two dextral strike slip faults, one of them in the northern part of the study area extending WNW-ESE direction and the other one in the southern part extending W-E direction.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section4\"\u003e\u003ch2\u003e4.2.1.4 Thickness or Isopach map of the phosphatic rocks\u003c/h2\u003e\u003cp\u003eThe prepared thickness map of the phosphatic rock (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e) show that:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eThe subsurface thickness of the phosphatic rocks ranges between 0.8 to 32 m. This great lateral variation in the thickness is related to the predominant structures.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe maximum thickness is recorded in northeast and southwest parts of Abu Tartur plateau.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e17\u003c/span\u003e illustrates the combination of the structure contour map of the basement surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e), the structure contour map of the top Nubian sandstone surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e), and the thickness map of phosphatic rocks (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e). From the cumulative figure (Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e17\u003c/span\u003e), It can be noticed that the maximum thickness of the phosphatic rocks is observed at the troughs of the syncline folds, which are located northeast and southwest of Abu Tartur plateau. Abu Tartur plateau is bounded by several faults with downthrow outward from the plateau. So, the present location of the Abu Tartur mine was mostly not the best location for underground mining and, accordingly, not economic.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003e4.3 Structure trends analysis of lineaments detected from Bouguer gravity and RTP aeromagnetic maps\u003c/h2\u003e\u003cp\u003eThe most important step in interpreting Bouguer gravity and RTP aeromagnetic data is turning them into tectonic information. Tectonic interpretation of a particular area is greatly influenced by the main structural characteristics on the basement surface that affect the sedimentary cover above. Main tectonic trends influencing the study region are visualized in the current work using trend analysis of the gravitational and magnetic fields as well as their derivatives. The digitizing techniques available in Rockware Software version15 \u003csup\u003e73\u003c/sup\u003e were used in tracing and measuring the structural lineaments. The main structural trends prevailing in the study area can be detected as follows: N-S trend, which azimuths from 0˚to 5˚ to the west or the east, NNE trend from 5˚ to 30˚ to the east, NNW trend from 5˚to 30˚ to the west, NE trend from 30˚to 60˚ to the east, NW trend from 30˚to 60˚ to the west, ENE trend from 60˚to 85˚ to the east, WNW trend from 60˚to 85˚ to the west and W-E trend from 85˚to 90˚ to the west or east. (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) summarizes the structural trends extracted from the gravity and magnetic data across different processing stages, including RTP, Bouguer, regional, residual, FVD, TDR, and AS maps.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary of the trends detected from different maps of the study area.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eDirections\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eCorresponding maps\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c8\" namest=\"c5\"\u003e\u003cp\u003eDomain Type\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e1st Trends\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e2nd Trends\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e3rd Trends\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003eMajor Trends\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003eMinor Trends\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRegional RTP\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRegional Bouguer\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eLocal RTP\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eLocal Bouguer\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eW-E\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eAS gravity, FVD RTP, FVD gravity, residual RTP, residual gravity, TDR RTP, TDR gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eRTP, regional gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eAS RTP, Bouguer gravity, regional RTP\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eENE\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eAS RTP, RTP, TDR RTP\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eFVD RTP, FVD gravity, regional RTP, regional gravity, residual RTP, residual gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eBouguer gravity, TDR gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNNE\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eBouguer gravity, FVD RTP\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eAS gravity, FVD gravity, regional gravity, TDR RTP\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eRegional RTP, Residual RTP, TDR gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e\u0026times;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNW\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eRegional RTP\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eAS RTP, Bouguer gravity, FVD gravity, regional gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eResidual RTP\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e\u0026times;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNNW\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eRegional gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eAS RTP, Bouguer gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eFVD gravity, RTP, regional RTP, TDR RTP\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e\u0026times;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e\u0026times;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWNW\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eRegional gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eAS RTP, RTP, regional RTP, TDR gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eBouguer gravity, FVD RTP, FVD gravity, residual gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e\u0026times;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNE\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003eBouguer gravity, regional gravity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003eAS RTP, AS gravity, RTP, regional RTP\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e\u0026radic;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e\u0026times;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e\u0026times;\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003ea)\u0026nbsp; \u0026nbsp;W-E Trend\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis is the most prominent trend recorded in the study area, it was found as first order in residual RTP, residual gravity, FVD RTP, FVD gravity, TDR RTP, TDR gravity and AS gravity (Figs. 19a, 19b, 19c, 19d, 19e, 19f and 20b), recorded as second order in RTP and regional gravity (Figs. 18a and 18d), and as third order in Bouguer gravity, regional RTP, and AS RTP (Figs. 18b, 18c and 20a). This trend has been recorded by several recent studies \u003csup\u003e56,74-76\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb)\u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;ENE-WSW Trend\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis trend has been verified through several recent studies \u003csup\u003e77,78\u003c/sup\u003e. In RTP, TDR RTP, and AS RTP (Figs. 18a, 19e and 20a) this trend is recorded as first order, observed as second order in regional RTP, regional gravity, residual RTP, and residual gravity, FVD RTP, and FVD gravity (Figs. 18c, 18d, 19a, 19b, 19c and 19d), and in the Bouguer gravity and TDR gravity (Figs. 18b and 19f), this trend is characterized as third order\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ec)\u0026nbsp; \u0026nbsp; NNE-SSW Trend\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis trend is observed as the first order in Bouguer gravity and FVD RTP (Figs. 18b and 19f), as second order in regional gravity, FVD gravity, TDR RTP, and AS gravity (Figs. 18d, 19d, 19e and 20b), and as third order in regional RTP, residual RTP and TDR gravity (Figs. 18c, 19a and 19f). This trend has been identified by many authors \u003csup\u003e79-81\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ed)\u0026nbsp; \u0026nbsp; NW-SE Trend\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis trend manifests as a first order in the regional RTP map (Fig. 18c), as a second order in Bouguer gravity, regional gravity, FVD gravity, and AS RTP (18b, 18d, 19d and 20a), and as a third order in residual RTP (Fig. 19a). This trend has been recorded by \u003csup\u003e67,76,82,83\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ee)\u0026nbsp; \u0026nbsp;NNW-SSE Trend\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOn the regional gravity (Fig. 18d), this trend appears as first order. Second order signature in Bouguer gravity and AS RTP (Figs. 18b and 20a), whereas third order expression in RTP, Regional RTP, FVD gravity and TDR RTP (Figs. 18a, 18c, 19d and 19e) This trend has been confirmed by several studies \u003csup\u003e74,84,85\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ef)\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eWNW-ESE Trend\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis trend is delineated as the first order in regional gravity (Fig. 18d), recorded as the second order in RTP, regional RTP, TDR gravity, and AS RTP (Figs. 18a, 18c, 19e and 20a), and in the Bouguer gravity, residual gravity, FVD RTP, and FVD gravity (Figs. 18b, 19b, 19c and 19d), this trend is characterized as the third order. This trend has been identified by \u003csup\u003e67,74,86,87\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eg)\u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eNE-SE Trend\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis trend has been verified through \u003csup\u003e74,75,84\u003c/sup\u003e. This trend is observed as second order in Bouguer gravity and regional gravity (Figs. 18b and 18d). It has appeared as a third order in RTP, regional RTP, AS RTP, and AS gravity (Figs. 18a, 18c, 20a and 20b).\u0026nbsp;\u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eThis study applied an integrated geophysical approach, combining aeromagnetic (RTP) and Bouguer gravity data, to characterize the subsurface structural framework of Abu Tartur Phosphate Mine (ATPM). The results provide critical insights into the geological controls on phosphate distribution, which are essential for optimal mine planning and sustainable resource utilization.\u003c/p\u003e\u003cp\u003eQualitative interpretation of the gravity and magnetic data revealed several dominant structural trends in the region, including W-E, ENE, NNE, NW, NNW, WNW, and NE directions. These trends are associated with both deep seated basement structures and shallower features observable near the surface. Quantitative analysis through 2D modelling confirmed the presence of complex subsurface structures, mainly comprising normal and strike slip faults as well as plunging and double plunging folds with axes trending NE-SW, NNW-SSE, and NW-SE.\u003c/p\u003e\u003cp\u003eThe remarkable feature of this study is the significant lateral variation in the thickness of the phosphatic rocks, ranging from 0.8 to 32 meters. The thinnest layers were identified in the currently exploited central plateau area, which likely contributed to the subeconomic performance and eventual closure of the underground mine. Conversely, the thickest phosphate deposits were found at the troughs of synclinal folds located northeast and southwest of the plateau zones that offer substantially greater mining potential.\u003c/p\u003e\u003cp\u003eThese results clearly demonstrate that the current ATPM site was suboptimal for underground mining and that better informed geophysical analysis could have prevented misallocation of resources. The integration of gravity and magnetic data, supported by borehole data and geological modelling, proved essential for delineating structurally controlled phosphate rich zones. This approach not only enhances the economic feasibility of future mining operations at ATPM but also provides a replicable framework for mineral exploration in structurally complex terrains elsewhere.\u003c/p\u003e\u003cp\u003eUltimately, this research underscores the importance of multidisciplinary geophysical characterization in guiding resource extraction, reducing risk and supporting long term sustainability in the mining sector.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eThe funding was provided by Science and Technology Development Fund through the Open Access agreement.\u003c/p\u003e\u003cp\u003eData availability\u003c/p\u003e\u003cp\u003eNo additional data to declare. All data generated or analyzed during this study are included within this manuscript\u003c/p\u003e\u003cp\u003eCompeting interests\u003c/p\u003e\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eG.MK.A conceptualized the study, performed geophysical data processing and interpretation, and led the manuscript writing. M.M.S contributed to the geological framework, structural analysis, and validation of results. G.Y.B. assisted in data visualization, map generation, and modeling. M.H.A. contributed to literature review, field data collection, and manuscript editing. All authors reviewed and approved the final version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGorman, M. R. \u0026amp; Dzombak, D. A. A review of sustainable mining and resource management: Transitioning from the life cycle of the mine to the life cycle of the mineral.\u003cem\u003e Resources Conservation Recycling\u003c/em\u003e \u003cstrong\u003e137\u003c/strong\u003e, 281-291.https://doi.org/10.1016/j.resconrec.2018.06.001 (2018).\u003c/li\u003e\n\u003cli\u003eLamghari, K.\u003cem\u003e et al.\u003c/em\u003e Sustainable phosphate mining: Enhancing efficiency in mining and pre-beneficiation processes. \u003cem\u003eJournal of Environmental Management\u003c/em\u003e \u003cstrong\u003e358\u003c/strong\u003e, 120833. https://doi.org/10.1016/j.jenvman.2024.120833 (2024).\u003c/li\u003e\n\u003cli\u003eMirzehi, M. \u0026amp; Afrapoli, A. M. Sustainable long-term production planning of open pit mines: An integrated framework for concurrent economical and environmental optimization. \u003cem\u003eResources Policy\u003c/em\u003e \u003cstrong\u003e94\u003c/strong\u003e, 105131.https://doi.org/10.1016/j.resourpol.2024.105131 (2024).\u003c/li\u003e\n\u003cli\u003ePavloudakis, F., Roumpos, C. \u0026amp; Spanidis, P.-M. Vol. 16 8393 (Sustainability 2024).\u003c/li\u003e\n\u003cli\u003eBatterham, R. The mine of the future\u0026ndash;even more sustainable. \u003cem\u003eMinerals Engineering\u003c/em\u003e \u003cstrong\u003e107\u003c/strong\u003e, 2-7.https://doi.org/10.1016/j.mineng.2016.11.001 (2017).\u003c/li\u003e\n\u003cli\u003eLittleboy, A.\u003cem\u003e et al.\u003c/em\u003e A sustainable future for mining by 2030 Insights from an expert focus group. \u003cem\u003eThe extractive industries society\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, 1086-1090. https://doi.org/10.1016/j.exis.2019.11.005 (2019).\u003c/li\u003e\n\u003cli\u003eMonteiro, N. B. R., da Silva, E. A. \u0026amp; Neto, J. M. M. Sustainable development goals in mining. \u003cem\u003eJournal of Cleaner Production\u003c/em\u003e \u003cstrong\u003e228\u003c/strong\u003e, 509-520. https://doi.org/10.1016/j.jclepro.2019.04.332 (2019).\u003c/li\u003e\n\u003cli\u003eHellal, F., El-Sayed, S., Zewainy, R. \u0026amp; Amer, A. Importance of phosphate pock application for sustaining agricultural production in Egypt. \u003cem\u003eBulletin of the National Research Centre\u003c/em\u003e \u003cstrong\u003e43\u003c/strong\u003e, 1-11.https://doi.org/10.1186/s42269-019-0050-9 (2019).\u003c/li\u003e\n\u003cli\u003eLyon, C.\u003cem\u003e et al.\u003c/em\u003e Five pillars for stakeholder analyses in sustainability transformations: The global case of phosphorus. \u003cem\u003eEnvironmental science policy\u003c/em\u003e \u003cstrong\u003e107\u003c/strong\u003e, 80-89. https://doi.org/10.1016/j.envsci.2020.02.019 (2020).\u003c/li\u003e\n\u003cli\u003eGupta, D., Chatterjee, S., Datta, S., Veer, V. \u0026amp; Walther, C. Role of phosphate fertilizers in heavy metal uptake and detoxification of toxic metals. \u003cem\u003eChemosphere\u003c/em\u003e \u003cstrong\u003e108\u003c/strong\u003e, 134-144.https://doi.org/10.1016/j.chemosphere.2014.01.030 (2014).\u003c/li\u003e\n\u003cli\u003eBindraban, P. S., Dimkpa, C. O., Pandey, R. \u0026amp; Soils, F. o. Exploring phosphorus fertilizers and fertilization strategies for improved human and environmental health. \u003cem\u003eBiology\u003c/em\u003e \u003cstrong\u003e56\u003c/strong\u003e, 299-317.https://doi.org/10.1007/s00374-019-01430-2 (2020).\u003c/li\u003e\n\u003cli\u003eCordell, D., Drangert, J.-O. \u0026amp; White, S. The story of phosphorus: global food security and food for thought. \u003cem\u003eGlobal environmental change\u003c/em\u003e \u003cstrong\u003e19\u003c/strong\u003e, 292-305. https://doi.org/10.1016/j.gloenvcha.2008.10.009 (2009).\u003c/li\u003e\n\u003cli\u003eHussein, M., Ibrahim, A. \u0026amp; Imbaby, S. Application of the rock mass classification systems to pillar design in longwall mining for Abu-Tartur longwall phosphate mining conditions.\u003cem\u003e JES. Journal of Engineering Sciences\u003c/em\u003e \u003cstrong\u003e41\u003c/strong\u003e, 2012-2020. https://dx.doi.org/10.21608/jesaun.2013.114931 (2013).\u003c/li\u003e\n\u003cli\u003eAl-Wakeel, M. I. Effect of mechanical treatment on the mineralogical constituents of Abu-Tartour phosphate ore, Egypt. \u003cem\u003eInternational Journal of Mineral Processing\u003c/em\u003e \u003cstrong\u003e75\u003c/strong\u003e, 101-112.https://doi.org/10.1016/j.minpro.2004.05.004 (2005).\u003c/li\u003e\n\u003cli\u003eOrabi, A.\u003cem\u003e et al.\u003c/em\u003e Extraction of rare earth elements from Abu\u0026ndash;Tartour wet process phosphoric acid using synthesized salicylaldehyde azine. \u003cem\u003eMinerals Engineering\u003c/em\u003e \u003cstrong\u003e122\u003c/strong\u003e, 113-121.https://doi.org/10.1016/j.mineng.2018.03.037 (2018).\u003c/li\u003e\n\u003cli\u003eHussein, M., Ibrahim, A. \u0026amp; Imbaby, S. Load calculations and selection of the powered supports based on rock mass classification and other formulae for Abu-Tartur longwall phosphate mining conditions. \u003cem\u003eJES. Journal of Engineering Sciences\u003c/em\u003e \u003cstrong\u003e41\u003c/strong\u003e, 1728-1742.https://dx.doi.org/10.21608/jesaun.2013.114900 (2013).\u003c/li\u003e\n\u003cli\u003eHussein, M., Imbaby, S. \u0026amp; Ibrahim, A. Panel width affected by rock mass classifications (Abu-Tartur Phosphate Mines). \u003cem\u003eJES. Journal of Engineering Sciences\u003c/em\u003e \u003cstrong\u003e41\u003c/strong\u003e, 1364-1379.https://dx.doi.org/10.21608/jesaun.2013.114796 (2013).\u003c/li\u003e\n\u003cli\u003eReedman, J. \u003cem\u003eTechniques in mineral exploration\u003c/em\u003e. (Springer Science \u0026amp; Business Media, 2012).\u003c/li\u003e\n\u003cli\u003eBhadra, B.\u003cem\u003e et al.\u003c/em\u003e Integrated remote sensing and geophysical techniques for shallow base metal deposits (Zn, Pb, Cu) below the gossan zone at Kalabar, Western Aravalli Belt, India. \u003cem\u003eJournal of Applied Geophysics\u003c/em\u003e \u003cstrong\u003e191\u003c/strong\u003e, 104365.https://doi.org/10.1016/j.jappgeo.2021.104365 (2021).\u003c/li\u003e\n\u003cli\u003eFaruwa, A. R.\u003cem\u003e et al.\u003c/em\u003e Airborne magnetic and radiometric mapping for litho-structural settings and its significance for bitumen mineralization over Agbabu bitumen-belt southwestern Nigeria. \u003cem\u003eJournal of African Earth Sciences\u003c/em\u003e \u003cstrong\u003e180\u003c/strong\u003e, 104222. https://doi.org/10.1016/j.jafrearsci.2021.104222 (2021).\u003c/li\u003e\n\u003cli\u003eEldougdoug, A.\u003cem\u003e et al.\u003c/em\u003e Exploring gold mineralization in altered ultramafic rocks in south Abu Marawat, Eastern Desert, Egypt. \u003cem\u003eScientific Reports\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 7293.https://doi.org/10.1038/s41598-023-33947-w (2023).\u003c/li\u003e\n\u003cli\u003ePelton, W. H., Ward, S. H., Hallof, P., Sill, W. \u0026amp; Nelson, P. H. Mineral discrimination and removal of inductive coupling with multifrequency IP. \u003cem\u003eGeophysics\u003c/em\u003e \u003cstrong\u003e43\u003c/strong\u003e, 588-609. https://doi.org/10.1190/1.1440839 (1978).\u003c/li\u003e\n\u003cli\u003eNelson, P. \u0026amp; Van Voorhis, G. Estimation of sulfide content from induced polarization data. \u003cem\u003eGeophysics\u003c/em\u003e \u003cstrong\u003e48\u003c/strong\u003e, 62-75.https://doi.org/10.1190/1.1441408 (1983).\u003c/li\u003e\n\u003cli\u003eGurin, G., Titov, K. \u0026amp; Ilyin, Y. Induced polarization of rocks containing metallic particles: Evidence of passivation effect. \u003cem\u003eGeophysical Research Letters\u003c/em\u003e \u003cstrong\u003e46\u003c/strong\u003e, 670-677. https://doi.org/10.1029/2018GL080107 (2019).\u003c/li\u003e\n\u003cli\u003eAlao, J. O., Lawal, K. M., Dewu, B. B. M. \u0026amp; Raimi, J. The studying of magnetic anomalies due to shallow underground targets and the environmental applications. \u003cem\u003eResults in Earth Sciences\u003c/em\u003e \u003cstrong\u003e2\u003c/strong\u003e, 100016.https://doi.org/10.1016/j.rines.2024.100016 (2024).\u003c/li\u003e\n\u003cli\u003eLi, K.\u003cem\u003e et al.\u003c/em\u003e Non-invasive geophysical methods for monitoring the shallow aquifer based on time-lapse electrical resistivity tomography, magnetic resonance sounding, and spontaneous potential methods. \u003cem\u003eScientific Reports\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, 7320.https://doi.org/10.1038/s41598-024-58062-2 (2024).\u003c/li\u003e\n\u003cli\u003eSaleh, A. \u0026amp; Gabr, S. S. Application of magnetic data and satellite spectral imaging in identifying gold mineralization zones and its associated subsurface structures at Fawakheir-Attala area, Central Eastern Desert, Egypt. \u003cem\u003eEnvironmental Earth Sciences\u003c/em\u003e \u003cstrong\u003e83\u003c/strong\u003e, 500.https://doi.org/10.1007/s12665-024-11776-y (2024).\u003c/li\u003e\n\u003cli\u003eBahi, A.\u003cem\u003e et al.\u003c/em\u003e Characterization of Mineral Meposits Using the Magnetic Method: The Case of the A\u0026iuml;n Beida Mine in Bouarfa, Morocco. \u003cem\u003eCivil Environmental Engineering\u003c/em\u003e \u003cstrong\u003e20\u003c/strong\u003e, 571-579.https://doi.org/10.2478/cee-2024-0043 (2024).\u003c/li\u003e\n\u003cli\u003eOladejo, O. P., Akinlabi, I. A. \u0026amp; Ogunkoya, C. O. Subsurface Qualitative Investigation for Mineral Exploration using Aeromagnetic Data. \u003cem\u003eDutse Journal of Pure and Applied Sciences\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e, 192-203.https://dx.doi.org/10.4314/dujopas.v9i4a.18 (2024).\u003c/li\u003e\n\u003cli\u003eDoyle, H. A. Geophysical exploration for gold\u0026mdash;a review. \u003cem\u003eGeophysics\u003c/em\u003e \u003cstrong\u003e55\u003c/strong\u003e, 134-146.https://doi.org/10.1190/1.1442820 (1990).\u003c/li\u003e\n\u003cli\u003eNabighian, M. N.\u003cem\u003e et al.\u003c/em\u003e Historical development of the gravity method in exploration. \u003cem\u003eGeophysics\u003c/em\u003e \u003cstrong\u003e70\u003c/strong\u003e, 63ND-89ND.https://doi.org/10.1190/1.2133785 (2005).\u003c/li\u003e\n\u003cli\u003eLi, H.\u003cem\u003e et al.\u003c/em\u003e Prospecting for ophiolite-type chromite deposit in Sartohay, West Junggar (NW China): Constraints from geological and geophysical data. \u003cem\u003eOre Geology Reviews\u003c/em\u003e \u003cstrong\u003e156\u003c/strong\u003e, 105379.https://doi.org/10.1016/j.oregeorev.2023.105379 (2023).\u003c/li\u003e\n\u003cli\u003eHornicka, E., Targosz, P., Loska, M. \u0026amp; Wojdyła, M. in \u003cem\u003eNSG2020 3rd Conference on Geophysics for Mineral Exploration and Mining.\u003c/em\u003e 1-5 (European Association of Geoscientists \u0026amp; Engineers).\u003c/li\u003e\n\u003cli\u003eShirazy, A., Shirazi, A., Nazerian, H., Khayer, K. \u0026amp; Hezarkhani, A. Geophysical study: Estimation of deposit depth using gravimetric data and Euler method (Jalalabad iron mine, kerman province of IRAN). \u003cem\u003eOpen Journal of Geology\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 340-355. https://doi.org/10.4236/ojg.2021.118018 (2021).\u003c/li\u003e\n\u003cli\u003eUnion, J. I. G. Geophysical exploration for manganese-some first hand examples from Keonjhar district, Orissa.\u003cem\u003e J. Ind. Geophys. Union\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 149-161 (2009).\u003c/li\u003e\n\u003cli\u003eZhang, J.\u003cem\u003e et al.\u003c/em\u003e Deep mineral exploration of the Jinchuan Cu\u0026ndash;Ni sulfide deposit based on aeromagnetic, gravity, and CSAMT methods. \u003cem\u003eMinerals Engineering\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e, 168 https://doi.org/10.3390/min10020168 (2020).\u003c/li\u003e\n\u003cli\u003eSun, J., Dong, L., Zhang, T., Shen, P. \u0026amp; Liu, D. J. C. E. J. Efficient recovery of copper from copper smelting slag by gravity separation combined with flotation. \u003cem\u003eChemical Engineering Journal\u003c/em\u003e, 153159.https://doi.org/10.1016/j.cej.2024.153159 (2024).\u003c/li\u003e\n\u003cli\u003eHasbrouck, W. \u0026amp; Hadsell, F. A. in \u003cem\u003eSecond Symposium on the Geology of Rocky Mountain Coal, Proceedings: Colorado Geological Survey Resource Series.\u003c/em\u003e 187-218.\u003c/li\u003e\n\u003cli\u003eXue, G.\u003cem\u003e et al.\u003c/em\u003e Delineation of sedimentary bauxite deposits in Shaanxi Province using the gravity and transient electromagnetic methods. \u003cem\u003eOre Geology Reviews\u003c/em\u003e \u003cstrong\u003e144\u003c/strong\u003e, 104865. https://doi.org/10.1016/j.oregeorev.2022.104865 (2022).\u003c/li\u003e\n\u003cli\u003eAli, M.\u003cem\u003e et al.\u003c/em\u003e Geoelectrical tomography data processing and interpretation for Pb-Zn-Ag mineral exploration in Nash Creek, Canada\u003cem\u003e,\u003c/em\u003e in \u003cem\u003eE3S Web of Conferences.\u003c/em\u003e p.00003 EDP Sciences (2020).\u003c/li\u003e\n\u003cli\u003eAli, M. A. H.\u003cem\u003e et al.\u003c/em\u003e Integration of electrical resistivity tomography and induced polarization for characterization and mapping of (Pb-Zn-Ag) sulfide deposits. \u003cem\u003eMinerals Engineering\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 986.https://doi.org/10.3390/min13070986 (2023).\u003c/li\u003e\n\u003cli\u003eEldosouky, A. M.\u003cem\u003e et al.\u003c/em\u003e in \u003cem\u003eGeospatial Analysis Applied to Mineral Exploration\u003c/em\u003e 189-231 (Elsevier, 2023).\u003c/li\u003e\n\u003cli\u003eGlenn, C. R. \u0026amp; Arthur, M. A. Anatomy and origin of a Cretaceous phosphorite‐greensand giant, Egypt. \u003cem\u003eSedimentology\u003c/em\u003e \u003cstrong\u003e37\u003c/strong\u003e, 123-154.https://doi.org/10.1111/j.1365-3091.1990.tb01986.x (1990).\u003c/li\u003e\n\u003cli\u003eZidan, I. J. Evaluation of phosphorite and Uranium in Lower phosphorite Member, Duwi Formation at Kummer area, South Esna, West Nile Valley, Egypt. \u003cem\u003eJ\u003c/em\u003e\u003cem\u003eournal of Sedimentological society of Egypt\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 143-154 (2013).\u003c/li\u003e\n\u003cli\u003eZidan, I. Geological and Mineralogical Studies of Abu Tartur Phosphates, Western Desert-Egypt, M. Sc. Thesis\u003cem\u003e, Fac. of Sci. Geology Dept., Al-Azhar University,\u003c/em\u003e (1998).\u003c/li\u003e\n\u003cli\u003eBaioumy, H. \u0026amp; Tada, R. Origin of late Cretaceous phosphorites in Egypt. \u003cem\u003eCretaceous Research\u003c/em\u003e \u003cstrong\u003e26\u003c/strong\u003e, 261-275.https://doi.org/10.1016/j.cretres.2004.12.004 (2005).\u003c/li\u003e\n\u003cli\u003eHendriks, F., Luger, P., Bowitz, J. \u0026amp; Kallenbach, H. Evolution of depositional environments of SE-Egypt during the Cretaceous and lower Tertiary. (1987).\u003c/li\u003e\n\u003cli\u003eSaid, R. The geology of Egypt: balkema. \u003cem\u003eRotterdam, Brookfield\u003c/em\u003e \u003cstrong\u003e734\u003c/strong\u003e (1990).\u003c/li\u003e\n\u003cli\u003eCoral, C. Geological map of Egypt, scale1:500,000. \u003cem\u003eThe Egyptian General Petroleum Corporation (EGPC), Egypt\u003c/em\u003e (1987).\u003c/li\u003e\n\u003cli\u003eSpector, A. \u0026amp; Grant, F. Statistical models for interpreting aeromagnetic data. \u003cem\u003eGeophysics\u003c/em\u003e \u003cstrong\u003e35\u003c/strong\u003e, 293-302.https://doi.org/10.1190/1.1440092 (1970).\u003c/li\u003e\n\u003cli\u003eBlakely, R. J. \u003cem\u003ePotential theory in gravity and magnetic applications\u003c/em\u003e. (Cambridge university press, 1996).\u003c/li\u003e\n\u003cli\u003eTelford, W. M., Geldart, L. P. \u0026amp; Sheriff, R. E. \u003cem\u003eApplied geophysics\u003c/em\u003e. (Cambridge university press, 1990).\u003c/li\u003e\n\u003cli\u003eNabighian, M. N. Toward a three-dimensional automatic interpretation of potential field data via generalized Hilbert transforms: Fundamental relations. \u003cem\u003eGeophysics\u003c/em\u003e \u003cstrong\u003e49\u003c/strong\u003e, 780-786.https://doi.org/10.1190/1.1441706 (1984).\u003c/li\u003e\n\u003cli\u003eVerduzco, B., Fairhead, J. D., Green, C. M. \u0026amp; MacKenzie, C. New insights into magnetic derivatives for structural mapping. \u003cem\u003eThe leading edge\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, 116-119. https://doi.org/10.1190/1.1651454 (2004).\u003c/li\u003e\n\u003cli\u003eMiller, H. G. \u0026amp; Singh, V. Potential field tilt\u0026mdash;a new concept for location of potential field sources. \u003cem\u003eJournal of applied Geophysics\u003c/em\u003e \u003cstrong\u003e32\u003c/strong\u003e, 213-217. https://doi.org/10.1016/0926-9851(94)90022-1 (1994).\u003c/li\u003e\n\u003cli\u003eMohamed, H. S., Senosy, M. M. \u0026amp; Abdel Zaher, M. Interactive interpretation of airborne gravity, magnetic, and drill-hole data within the crustal framework of the northern Western Desert, Egypt. \u003cem\u003eJournal of Applied Geophysics\u003c/em\u003e \u003cstrong\u003e134\u003c/strong\u003e, 291-302. https://doi.org/10.1016/j.jappgeo.2016.09.002 (2016).\u003c/li\u003e\n\u003cli\u003eRoest, W. R., Verhoef, J. \u0026amp; Pilkington, M. Magnetic interpretation using the 3-D analytic signal. \u003cem\u003eGeophysics\u003c/em\u003e \u003cstrong\u003e57\u003c/strong\u003e, 116-125.https://doi.org/10.1190/1.1443174 (1992).\u003c/li\u003e\n\u003cli\u003eMacLeod, I. N., Jones, K. \u0026amp; Dai, T. F. 3-D analytic signal in the interpretation of total magnetic field data at low magnetic latitudes. \u003cem\u003eExploration geophysics\u003c/em\u003e \u003cstrong\u003e24\u003c/strong\u003e, 679-688. https://doi.org/10.1071/EG993679 (1993).\u003c/li\u003e\n\u003cli\u003eGeosoft, I. OASIS Montaj. version 8.4 user guide. \u003cem\u003eToronto, Canada: Geosoft Incorporated\u003c/em\u003e (2015).\u003c/li\u003e\n\u003cli\u003eSoftware, G. Surfer\u0026reg;: Contouring and 3D mapping for scientists and engineers (Version 15) \u003cem\u003e[Computer software]. Golden Software\u003c/em\u003e (2017).\u003c/li\u003e\n\u003cli\u003eSenosy, M. Application of density contrast stripping in studying subsurface geologic structures: a case study El-Kharga Oasis, western Desert, Egypt.\u003cem\u003e Egyptian J. Geol.\u003c/em\u003e \u003cstrong\u003e47\u003c/strong\u003e, 387-404 (2003).\u003c/li\u003e\n\u003cli\u003eRizk, S. A. M. Highlights on the beneficiation trials of the Egyptian phosphate ores. \u003cem\u003eJES. Journal of Engineering Sciences\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 1-21. https://dx.doi.org/10.21608/jesaun.2021.100795.1083 (2022).\u003c/li\u003e\n\u003cli\u003eElmaadawy, K. G., Ezz El Din, M., Khalid, A. \u0026amp; Abouzeid, A. Mineral industry in Egypt\u0026ndash;part II non metallic commodities\u0026ndash;phosphate rocks. \u003cem\u003eJ Min World Express\u003c/em\u003e \u003cstrong\u003e4\u003c/strong\u003e, 1-18. http://dx.doi.org/10.14355/mwe.2015.04.001 (2015).\u003c/li\u003e\n\u003cli\u003eMahmoud, M. S. Palynology and palaeoenvironment of the Quseir Formation (Campanian) from central Egypt. \u003cem\u003eJournal of African Earth Sciences\u003c/em\u003e \u003cstrong\u003e36\u003c/strong\u003e, 135-148. https://doi.org/10.1016/S0899-5362(03)00047-2 (2003).\u003c/li\u003e\n\u003cli\u003eSenosy, M., Youssef, M. \u0026amp; Zaher, M. A. Sedimentary cover in the South Western Desert of Egypt as deduced from Bouguer gravity and drill-hole data. \u003cem\u003eJournal of African Earth Sciences\u003c/em\u003e \u003cstrong\u003e82\u003c/strong\u003e, 1-14.https://doi.org/10.1016/j.jafrearsci.2013.02.001 (2013).\u003c/li\u003e\n\u003cli\u003eIbrahim, S., El Kammar, A. \u0026amp; Guda, A. Characterization and separation of pyrite from Abu Tartur black shale. \u003cem\u003eInternational Journal of Mining Science Technology\u003c/em\u003e \u003cstrong\u003e25\u003c/strong\u003e, 565-571.https://doi.org/10.1016/j.ijmst.2015.05.008 (2015).\u003c/li\u003e\n\u003cli\u003eZaher, M. A., Senosy, M., Youssef, M. \u0026amp; Ehara, S. Thickness variation of the sedimentary cover in the South Western Desert of Egypt as deduced from Bouguer gravity and drill-hole data using neural network method. \u003cem\u003eEarth planets space\u003c/em\u003e \u003cstrong\u003e61\u003c/strong\u003e, 659-674. https://doi.org/10.1186/BF03353175 (2009).\u003c/li\u003e\n\u003cli\u003eEl Maghraby, A. Phosphate mining wastes at Abu Tartur mine area, Western Desert of Egypt. \u003cem\u003eAustralian Journal of basic and Applied Sciences\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e, 231-248 (2012).\u003c/li\u003e\n\u003cli\u003eTelford, W., Geldart, L., Sheriff, R. \u0026amp; Keys, D. J. L. p. Applied geophysics cambridge university press. (1976).\u003c/li\u003e\n\u003cli\u003eSharma, P. V. \u003cem\u003eEnvironmental and engineering geophysics\u003c/em\u003e. (Cambridge university press, 1997).\u003c/li\u003e\n\u003cli\u003eKearey, P., Brooks, M. \u0026amp; Hill, I. \u003cem\u003eAn introduction to geophysical exploration\u003c/em\u003e. Vol. 4 (John Wiley \u0026amp; Sons, 2002).\u003c/li\u003e\n\u003cli\u003eEl-Sirafe, A. M., El-Gamili, M. M., El-Manawy, M. E. \u0026amp; El-Mdiegy, M. A. Structural Interpretation of the Airborne Magnetic Survey Data of Kharga-Dakhla Oases Area, Southern Western Desert, Egypt \u003cem\u003eSci. J. Fac Sci Minufiya University\u003c/em\u003e\u003cstrong\u003e 14\u003c/strong\u003e, 233-257 (2000).\u003c/li\u003e\n\u003cli\u003eRockWare. RockWorks15: Geological data management, mapping, and visualization software. \u003cem\u003eRockWare, Inc., Golden, Colorado, USA (2013)\u003c/em\u003e.\u003c/li\u003e\n\u003cli\u003eSaada, S. \u0026amp; El-Khadragy, A. An integrated study of gravity and magnetic data on west El-Minya area, Western Desert, Egypt. \u003cem\u003eJournal of American Science\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 169-184. https://doi.org/10.7537/marsjas111215.23 (2015).\u003c/li\u003e\n\u003cli\u003eSaada, S. A.\u003cem\u003e et al.\u003c/em\u003e Understanding the structural framework controlling the sedimentary basins from the integration of gravity and magnetic data: A case study from the east of the Qattara Depression area, Egypt. \u003cem\u003eJournal of King Saud University-Science\u003c/em\u003e \u003cstrong\u003e34\u003c/strong\u003e, 101808. https://doi.org/10.1016/j.jksus.2021.101808 (2022).\u003c/li\u003e\n\u003cli\u003eMohamed, A., Alarifi, S. S. \u0026amp; Abdelrady, A. Sedimentary cover and structural trends affecting the groundwater flow in the Nubian Sandstone Aquifer System: Inferences from geophysical, field and geochemical data. \u003cem\u003eFrontiers in earth science\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 1173569. https://doi.org/10.3389/feart.2023.1173569 (2023).\u003c/li\u003e\n\u003cli\u003eElmasry, A., Abdel Zaher, M., Madani, A. \u0026amp; Nassar, T. Exploration of Geothermal Resources Utilizing Geophysical and Borehole Data in the Abu Gharadig Basin of Egypt\u0026rsquo;s Northern Western Desert. \u003cem\u003ePure and Applied Geophysics\u003c/em\u003e \u003cstrong\u003e179\u003c/strong\u003e, 4503-4520. https://doi.org/10.1007/s00024-022-03180-z (2022).\u003c/li\u003e\n\u003cli\u003eKamal, M.\u003cem\u003e et al.\u003c/em\u003e Integrated geophysical techniques applied for petroleum basins structural characterization in the central part of the Western Desert, Egypt. \u003cem\u003eOpen Chemistry\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 20220293.https://doi.org/10.1515/chem-2022-0293 (2023).\u003c/li\u003e\n\u003cli\u003eAbdelhamed, B. M., Awad Sultan Araffa, S. \u0026amp; Abdelhafeez, T. Geophysical studies around abu gharadig basin, North Western desert, Egypt. \u003cem\u003eExploration Geophysics\u003c/em\u003e \u003cstrong\u003e54\u003c/strong\u003e, 329-351.https://doi.org/10.1080/08123985.2022.2123736 (2023).\u003c/li\u003e\n\u003cli\u003eMohamed, W. H., Elyaseer, M. H. \u0026amp; Sabra, M. E. M. Structural lineament analysis of the Bir El-Qash area, Central Eastern Desert, Egypt, using integrated remote sensing and aeromagnetic data. \u003cem\u003eScientific Reports\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 21569.https://doi.org/10.1038/s41598-023-48660-x (2023).\u003c/li\u003e\n\u003cli\u003eAraffa, S.\u003cem\u003e et al.\u003c/em\u003e Geophysical and Remote Sensing Data for Delineating Structural Elements at El Hammam Area, Northern Part of Western Desert, Egypt. \u003cem\u003eGeotectonics\u003c/em\u003e \u003cstrong\u003e58\u003c/strong\u003e, 218-233. https://doi.org/10.1134/S0016852124700146 (2024).\u003c/li\u003e\n\u003cli\u003eYoussef, M. I. Structural pattern of Egypt and its interpretation. \u003cem\u003eAAPG Bulletin\u003c/em\u003e \u003cstrong\u003e52\u003c/strong\u003e, 601-614. https://doi.org/10.1306/5D25C44D-16C1-11D7-8645000102C1865D (1968).\u003c/li\u003e\n\u003cli\u003eAbdel Zaher, M.\u003cem\u003e et al.\u003c/em\u003e Origin of mysterious geothermal gas emissions in the middle of the Western Desert, stable shelf area, Dakhla Oasis, Egypt. \u003cem\u003eScientific Reports\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 16466. https://doi.org/10.1038/s41598-023-43492-1 (2023).\u003c/li\u003e\n\u003cli\u003eSaad, M., El-Khadragy, A., Shabaan, M. \u0026amp; Azab, A. An integrated study of gravity and magnetic data on South Sitra area, Western Desert, Egypt. \u003cem\u003eJ Appl Sci Res\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, 616-636 (2010).\u003c/li\u003e\n\u003cli\u003eSaada, S., Zahra, H. \u0026amp; El-Khadragy, A. Structural pattern and crustal modeling of the central northern part of Egypt, using Bouguer gravity data. \u003cem\u003eJournal. Applied sciences research\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e (2013).\u003c/li\u003e\n\u003cli\u003eKhalil, A., Hafeez, T. H. A., Saleh, H. S., Mohamed, W. H. \u0026amp; Geophysics. Inferring the subsurface basement depth and the structural trends as deduced from aeromagnetic data at West Beni Suef area, Western Desert, Egypt. \u003cem\u003eNRIAG Journal of Astronomy\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 380-392. https://doi.org/10.1016/j.nrjag.2016.08.001 (2016).\u003c/li\u003e\n\u003cli\u003eElmaadawy, K. G. \u0026amp; El-Ashmony, M. R. Tectonostratigraphic evolution of the new frontier Foram Basin and implications for hydrocarbon potential, Western Desert, Egypt. \u003cem\u003eJournal of African Earth Sciences\u003c/em\u003e \u003cstrong\u003e177\u003c/strong\u003e, 104142.https://doi.org/10.1016/j.jafrearsci.2021.104142 (2021).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Abu Tartur Mine, Aeromagnetic, Bouguer gravity, Subsurface structures","lastPublishedDoi":"10.21203/rs.3.rs-6981993/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6981993/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eOptimal planning of Abu Tartur Mine (ATPM), in Egypt, requires comprehensive understanding of the region's phosphate ore geology. The recent closure of the subsurface ATPM was primarily due to insufficient geological data, including unrecognized faults that concealed phosphate beds. The present study is integrating gravity and magnetic geophysical methods to characterize the phosphate beds and identify geological structures. Aeromagnetic Reduced to Pole (RTP) and Bouguer anomaly data were used, with filters (analytical signal, first vertical derivative, high pass and low pass (applied to enhance interpretation. Through 2D gravity and magnetic modelling, the subsurface sedimentary sequence above the basement rocks was defined. The subsea depth to the subsurface rock layer boundaries were determined. Consequently, structure contour maps were created for the basement and the Nubian sandstone surfaces, along with Isopach map of the phosphatic rocks. Maps and filtered data revealed the predominant subsurface structures controlling the phosphate distribution. These structures are folds (plunging and double plunging synclines and anticlines with axes trending NE-SW, NNW-SSE, and NW-SE) and faults (normal and strike slip). Normal faults bound the ATPM plateau with downthrow directions outward. Phosphatic rocks thickness varies from 0.8 to 32 meter. The limited thickness is recorded in the present ATPM location, whereas the maximum thickness is observed at the troughs of the syncline folds located northeast and southwest of the plateau. Therefore, the ATPM location was suboptimal and uneconomical, while the northeast and southwest areas offer more promising targets for phosphate extraction. This misallocation likely contributed to mine failure.\u003c/p\u003e","manuscriptTitle":"Geophysical Characterization of Subsurface Structures for Optimal Planning in the Abu Tartur Phosphate Mine","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-11 10:02:46","doi":"10.21203/rs.3.rs-6981993/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-10T12:45:32+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-28T15:49:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"20423603118877966993211868593430483530","date":"2026-02-08T06:39:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"56617789199182495272305632453515637660","date":"2026-02-07T20:18:01+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-29T11:16:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"269744031371763567438592406957247368736","date":"2025-07-14T03:38:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"248824084735643775331525785607127161388","date":"2025-07-13T18:29:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"282841806432935531459308502416450849143","date":"2025-07-08T19:55:48+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-08T18:26:42+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-08T18:24:28+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-07-08T18:21:56+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-01T13:31:31+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-07-01T13:25:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1e9950bd-dce6-452d-bf73-bb71e5cd804d","owner":[],"postedDate":"July 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":51275761,"name":"Earth and environmental sciences/Solid earth sciences/Geology"},{"id":51275762,"name":"Earth and environmental sciences/Solid earth sciences/Geophysics"}],"tags":[],"updatedAt":"2026-04-27T16:00:23+00:00","versionOfRecord":{"articleIdentity":"rs-6981993","link":"https://doi.org/10.1038/s41598-026-48186-y","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-04-21 15:56:55","publishedOnDateReadable":"April 21st, 2026"},"versionCreatedAt":"2025-07-11 10:02:46","video":"","vorDoi":"10.1038/s41598-026-48186-y","vorDoiUrl":"https://doi.org/10.1038/s41598-026-48186-y","workflowStages":[]},"version":"v1","identity":"rs-6981993","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6981993","identity":"rs-6981993","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}