Gamma-ray Spectrometric Data Research Articles

Radioactive potentiality and uranium migration as assessed from airborne gamma-ray spectrometric data, north Wadi Qena area, Northern Eastern Desert, Egypt

Radioactive potentiality and uranium migration as assessed from airborne gamma-ray spectrometric data, north Wadi Qena area, Northern Eastern Desert, Egypt

A multi-disciplinary approach for uranium exploration using remote sensing and airborne gamma-ray spectrometry data in the Gebel Duwi area, Central Eastern Desert, Egypt

Uranium exploration plays a pivotal role in meeting global energy demands and advancing nuclear technology. This study presents a comprehensive approach to uranium exploration in the Gebel Duwi area of the Central Eastern Desert of Egypt, utilizing remote sensing and airborne gamma-ray spectrometric data. Multispectral remote sensing techniques, including Principal Component Analysis (PCA), Minimum Noise Fraction (MNF), and Band Ratioing (BR), are employed to identify lithological units and hydrothermal alteration zones associated with uranium deposition, such as iron oxides, argillic, propylitic, and phyllic alterations. Additionally, airborne gamma-ray spectrometry data provide insights into the spatial distribution of radioelements, including uranium (eU), thorium (eTh), and potassium (K), as well as radioelement ratios (eU/eTh, eU/K, and eTh/K). The uranium migration index map (eU-(eTh/3.5)) and the F-parameter map (K*(eU/eTh)) have been generated to investigate the movement of uranium within various geological zones and characterize anomalous uranium concentrations. Statistical analyses, including mean (X), standard deviation (S), and coefficient of variability (C.V.), are conducted to identify uranium-rich zones. The integration of these datasets enables the generation of a uranium potential map highlighting areas of elevated concentrations indicative of uranium mineralization. Field observations and mineralogical analyses of collected samples validate our findings, confirming the presence of minerals associated with uranium mineralization in mapped high-potential areas. The significance of minerals like Fe-Chlorite, Fe-Mg-Chlorite, ferrihydrite, goethite, calcite, muscovite, dolomite, actinolite, vermiculite, and gypsum in indicating potential uranium mineralization processes underscores the importance of our results.

Evaluation of the environmental and structural impacts on urban expansion using airborne geophysical data at Hurghada city, Northern Eastern Desert, Egypt.

Airborne gamma-ray spectrometric and magnetic data were processed and interpreted aiming to evaluate the environmental and structural impacts on urban expansion, Hurghada City, Northern Eastern Desert, Egypt. The eastern (coastal area), northern, and southeastern parts of the study area possess the lowest level of absorbed dose rate (ADR) and annual effective dose equivalent (AEDE), which were estimated from the airborne gamma-ray spectral data of this area. Consequently, these parts are considered as suitable sites for urban expansion from the radioactivity point of view. The relatively high level of ADR and AEDE is associated with granitic rocks, some parts of Gabir formation and recent Wadi sediments, situated at southwestern, central, and eastern parts of the study area. The ADR and AEDE of these parts are considered harmful to individuals. Airborne magnetic data were also used to detect major structures that may affect various construction projects in the study area in the future. The NNW-SSE, NW-SE, N-S, and NE-SW trends represent the common structures in the study area. The obtained results of airborne gamma-ray spectrometric and magnetic data illustrated that the urban expansion should not be constructed to the west of the ring road. However, site investigations must be carried out on this part of the study area before starting any construction projects there. The present study proved the important role of airborne gamma-ray spectrometric and magnetic surveys as useful tools to delineate the environmental and structural impacts on urban expansion.

Regolith mapping using airborne gamma-ray spectrometry in central Brazil

In deeply weathered terrains, with high geological diversity and scarce outcrops, the lateritic regolith features support mineral research. Predictive regolith mapping uses spatial modeling and airborne gamma-ray spectrometric data to locate weathered residual products, such as the ferruginous lateritic duricrusts found in tropical regions. Although the regolith materials exhibit qualitative similarities in their gamma-ray spectrometric responses in RGB (KThU) images, the Boolean and fuzzy approaches highlighted differences that allows for mapping the regolith weathering residual products on a wide geodiversity protoliths. Two inference systems were used, one identified the ferruginous lateritic duricrusts and oxisols derived from the felsic/pelitc and mafic rocks types (TP test procedures), and the other identified solely those derived exclusively from mafic rocks (TPM test procedures). Cutoff values for the conjunction eTh/K ∩ eU/K ∩ eTh ∩ K (TP-4) using Boolean logic, provided the most accurate regolith map (accuracy = 95%) among the various tests carried out and indicate that in 28.6% of the total study area, there are lateritic duricrust and oxisols relative to rocks, saprolites, mottled horizons and other soils type. The eTh cutoff value > 4.4 ppm was used to exclude mafic rocks and associated soils, and the K value < 1.3% to exclude rocks with eTh/K and eU/K values similar to the lateritic duricrusts and oxisols. For mapping the lateritic duricrusts derived exclusively from the mafic rocks the conjunction of eTh ∩ eU/K ∩ eTh/K ∩ K ∩ eU (TPM-3) fuzzified by the large membership function was the most efficient. The eU variable with values < 1.21 ppm helps improve the effectiveness of this procedure. The generated predictive map indicated that in about ∼12% (657.9 km2) of the total study area, there are lateritic duricrusts and oxisols derived from mafic rocks. Therefore, a successful method of mapping vast areas from complicated lateritic regolith mosaic derived from a large geodiversity is to apply specific plugins for data fuzzification, supported by observations from field outcrops.

KPLO gamma-ray spectrometer (KGRS) data processing with Python

KPLO gamma-ray spectrometer (KGRS) data processing with Python

Atmospheric CO2 Depletion Near the Surface in the Martian Polar Regions

AbstractThe kinetic temperature of the Martian seasonal caps is controlled by the partial pressure of atmospheric CO2 at the surface. When carbon dioxide condenses, typically near the poles, light non‐condensable species (Ar, N2, CO, etc.) accumulate in the atmosphere, resulting in a decrease of the CO2 partial pressure and depressing the local frost point temperature. The buoyant air should mix laterally and vertically within the polar vortices. Observations show that the Martian seasonal caps' kinetic temperatures are ∼0–4 K below the expected CO2 frost point, depending on latitude and season, indicating atmospheric CO2 gas depletion at the surface/atmosphere interface. In the North and South, we find relatively similar non‐condensable peak enhancement factors (e.g., EFNC ∼ 6–8, up to ∼8.7 in the North) at most latitudes, confirming the efficient meridional mixing within the polar vortices, despite steep surface condensation gradients. In the South, this surface enhancement is similar to column‐integrated values derived from Gamma Ray Spectrometer data, indicating efficient vertical mixing. But in the North, the surface depletion is much larger than in the entire column, suggesting poor vertical mixing. Reduced infrared emission of the seasonal caps stemming from CO2 depletion is not a major energy balance factor. This work illustrates how the atmosphere's composition at the surface can be significantly different from column‐integrated values.

Radiometric Mapping for The Identification of Hydrothermally Altered Zones Related to Gold Mineralization in Ife–Ilesa Schist Belt, Southwestern Nigeria

This study presents the interpretation of airborne gamma ray spectrometric data to delineate hydrothermally altered zones related to gold mineralization in the Ife–Ilesa Schist belt. K/eTh, Kd and F–Maps highlighting Potassic alterations related to gold mineralization were processed on the Oasis Montaj software and subsequently integrated using fuzzy logic modeling to produce the hydrothermal alteration map of the study area. The C–A fractal analysis was applied to the final hydrothermal map and was able to classify the study area into background, very low, low, moderate, high and very high alteration. These classes reflect the pervasive hydrothermal alteration style of the study area. The hydrothermally altered areas are evident on granitoids and areas proximal to it indicating that granitoids are proxies of heat source. Occurrence of active mining sites in the area agrees with the generated hydrothermal alteration map of the study area with 81% agreement. It therefore shows that radiometric method is a veritable method in mapping hydrothermal alteration areas. The use of radiometric method only cannot reliably map areas of gold mineralization as mineralization can be associated with several other processes. Hence, other methods involving geochemical and magnetic methods including GIS tools can be employed for further prospecting.

Delineation of hydrothermal alteration zones associated with mineral deposits, using remote sensing and airborne geophysics data. A case study: El-Bakriya area, Central Eastern Desert, Egypt

El-Bakriya area is situated in the Central Eastern Desert of Egypt. It includes several mineral occurrences and/or deposits. Data from remote sensing and airborne geophysics (gamma-ray and magnetic) were combined to identify the hydrothermal alteration zones and structures related to these occurrences. Various processing of ASTER satellite images revealed fifteen zones of high probability for metallic mineralizations. Airborne gamma-ray spectrometric data clarify K-enrichment zones, which are correlated geologically with the distribution of calc-alkaline, alkali feldspar granites (Younger granites), and calc-alkaline quartzdiorites to granodiorites (Older granites), as well as basement metavolcanics and metasediments. An integrated hydrothermal alteration map was constructed, based on both ASTER remote sensing and airborne gamma-ray spectrometric data. This map delineates some metallic mineral occurrences and/or deposits, which are located in the detected hydrothermal alteration zones. Besides, it displays new potential zones for mineralization, such as: Gabal (G.) El-Shalul, G. El-Bakriya, G. Siwat El-Arsha and G. Umm Bisilla. The geologic and airborne magnetic maps demonstrate five structural lineament trends of E–W, ENE–WSW, NE–SW, NW–SE, and NNW–SSE directions, which might act as pathways to transport the hydrothermal solutions in the study area.

IDENTIFICATION OF AREAS OF HIGH POTENTIAL-BEARING MINERALIZATIONS, EASTERN DESERT OF EGYPT: INSIGHTS FROM AIRBORNE GAMMA-RAY SPECTROMETRIC DATA.

A major number of mineral deposits are related to hydrothermal processes. Therefore, the mapping of the hydrothermally alteration areas, connected with mineralization, is crucial in the search for metal deposits. To achieve this purpose, areas of hydrothermal alterations are targeted by processing the airborne gamma-ray spectrometric data to detect areas enriched in potassium that may indicate the existence of potassic alteration zones, which are often associated with hydrothermal alterations accompanied by mineral deposits. Data processing and analysis were performed using the K/eTh ratio, deviation of ideal potassium (Kd) and F-parameter. Besides, determining the environmental radiation risk due to the fact that the study area contains many excavation sites for various mining materials and quarries. Hydrothermal alteration indicator maps show five known mineralizations of gold, copper, molybdenum, fluorite and wolframite, which are associated with hydrothermal processes that took place in the study area. It is possible to note the intimate correlation of mineral deposits present in areas with high potassium content. Positive correlation between the computed hydrothermal alteration indicators (K/eTh, Kd and F-parameter), shown on the ternary image map, revealed favorable high and intermediate targets for the detection of various mineral deposits in the study area. On the other hand, the estimated mean values of absorbed dose rate for all rock units were within the permissible range (28-120 nGy h-1), and the mean annual effective dose rate was below the permissible limit of 1.0mSv y-1 for these rocks.

Using of airborne gamma-ray spectrometric data to the exposure of potassic alteration -recognition of alteration relates to gold mineralization

It is well known that many mineral deposits are related to hydrothermal processes, especially auriferous deposits. In this research paper, we show how to distinguish areas that have experienced hydrothermal activity, by construing airborne gamma-ray spectrometry data, especially potassium. An indirect application of aerial gamma-ray spectrometry technique is used to detect possible minerals deposits.In this region, an airborne gamma ray survey (K, eU and eTh) was carried out, based on irregular K, “F” parameter -, and Th-normalized of the K and eU anomalies. This work exhibits the mapping of hydrothermal regions possibly showing gold mineralization and the pointing out of new geological portions for this sequence, establishing prospective criteria for regional mineral exploration.We can suggest a new exploratory target, the area that is located next to Jabal Al-Ardiya (white colour on ternary map), which is characterized by high values of F-parameter, KD%, and K/eTh. Besides, enriched areas are found scattered in the north-eastern side of the study area. As result, the airborne gamma ray spectromertic data, might be used for estimation of prospective Gold Ore zones associated with the potassium alteration."

A comprehensive study for the airborne gamma-rays spectrometry results of Gabal El-Hassnawia, Central Eastern Desert, Egypt

The present study utilizes the airborne gamma-ray spectrometric data of Gabal El-Hassnawia and its vicinity in an attempt to refine the surface geological mapping and recognize the radioelements occurrences. The statistically analysed surface lineaments derived from the Landsat image proved that they are oriented to the NW, NNW, N–S, and ENE trends. Qualitatively, the highest radiometric levels are related to the younger granites, the intermediate levels are observed over the Hammamat sediments and the acidic metavolcanics while the low levels are coinciding with the metasediments, ultramafites and basic to intermediate metavolcanics. The composite images show a good close correlation with the geologically mapped rock units. The factor analysis proved that the radiometric variables uranium (eU), potassium (K) and thorium (eTh) as well as total count (TC) are highly correlated positively with each other. Three principal factors F1, F2 and F3 are extracted from the data and their scores were used in differentiating the rock types according to their radiometric levels; consequently, nine interpreted litho-radiometric units were identified. Three types of younger granites and two types of Hammamat sediments could be distinguished among the nine units. These units are subjected to statistical treatment with the goal of identifying the uranium occurrences that exceeds X + 2S and X + 3S as targets of exploration. Accordingly, it is found that the uranium province zones are related to the three types of granite (G1, G2 and G3), the second type of Hammamat sediment (H2) and more or less the acidic metavolcanics. The uranium migration indicated that the second type of Hammamat sediment (H-2) is the only unit that the uranium is migrated in whereas; the uranium is migrated out in all other units.

Continental magmatic arc rotation during the assembly of western Gondwana

The Ceará Central Domain (CCD) is part of the Borborema Province and is delimited by two major NE-SW-trending strike-slip zones associated with the Transbrasiliano and Senador Pompeu lineaments. These two strike-slip zones formed in Neoproterozoic/Early Cambrian times under ductile conditions and underwent several brittle-ductile and brittle reactivation events from 540 Ma onwards, which affected Precambrian and Phanerozoic rocks, respectively, causing ductile and brittle-ductile and brittle deformation. The Transbrasiliano Lineament is an NNE-SSW-trending, 4000 km-long structure marked by strong magnetic anomalies. It is interpreted to represent a mega-suture active during the Gondwana amalgamation and/or the post-collisional shearing. The Santa Quitéria Continental Magmatic Arc, located between both lineaments, consists of a Neoproterozoic (830-620 Ma) gneissic-migmatitic association affected by collisional metamorphism (640-615 Ma). This arc has been dissected, dislocated, and rotated under brittle-ductile and brittle conditions by a set of secondary strike-slip faults, possibly interconnected with the two major Transbrasiliano and Senador Pompeu lineaments, and most likely have been contemporarily active throughout history. The roughly NNW-SSE-trending Tauá Fault, located southwest of CCD, appears to relate to both fault systems. A closer inspection of gamma-ray spectrometric data suggests a complex network of interconnecting E-W-trending brittle transcurrent faults, some of which show dextral and/or sinistral kinematics, displacing the Santa Quitéria Continental Magmatic Arc and Canindé-Independência units. We suggest a paleo-dextral ductile deformation of the Santa Quitéria Continental Magmatic Arc resulting from the coeval transcurrent activity along Transbrasiliano and Senador Pompeu lineaments. These strike-slip mega-shear zones developed an intricate pattern of the minor (first-, second-, and third stages) interconnecting strike-slip faults, along which the Santa Quitéria Continental Magmatic Arc has been displaced and rotated, under conditions that changed from ductile to brittle-ductile to brittle through time.

Aerial gamma-ray spectrometric survey data as a guide for probable hydrocarbon accumulations at Abu-Zeneima/Al-Tur area, Southwestern Sinai, Egypt

A method using surface and aerial gamma-ray spectral measurements to explore the hydrocarbon accumulations in Abu-Zeneima/Al-Tur area of Southwestern Sinai, Egypt, was selected due to both its structural setting and its location in close proximity to the Gulf of Suez, which represents one of the important sites of oil production in Egypt.Examination of the normalized potassium map (KD %) shows low concentrations above Abu-Alaqah, Thebes, and Kariem formations, while normalized equivalent uranium map (eUD %) shows a high concentration above these formations. The Deviation of Radio-Active Derivative (DRAD) map shows some of the delineated high positive DRAD anomalies, which are elongated in the NW–SE direction and related to Abu-Alaqah, Thebes, and Kariem formations.Data from every formation and rock unit as well as each flight line were extracted in XYZ format and evaluated with simple statistical applications. The DRAD arithmetic means plus three standard deviations (x + 3s) and plus two standard deviations (x + 2s) for the data set all over the study area were computed and reached the values of 2.5 and 2.1, respectively. Any single point that possesses a value greater than these two values should have a probability of 99.7% and 95%, respectively, of possible petroleum accumulations and represents a sure anomaly. The use of these criteria helped identify Abu-Alaqah, Thebes, and Kariem formations. Moreover, five zones along four flight lines correlating geologically with Abu-Alaqah, Thebes, and Kariem formations have sure anomalies. This might indicate a prospective possibility of feasible subsurface petroleum accumulations in Abu-Zeneima/Al-Tur area, Southwestern Sinai, Egypt.

Structural and mineral exploration study at the transition zone between the North and the Central Eastern Desert, Egypt, using airborne magnetic and gamma-ray spectrometric data

The transition zone between the North and the Central Eastern Desert of Egypt has been investigated using airborne magnetic and radiometric data to better characterize the subsurface structures, the tectonic framework, and mineral occurrences in the area. The magnetic data were subjected to several filtering and depth estimation techniques including edge detectors, Euler deconvolution, 2D forward modeling and 3D inversion. Statistical trend analysis of the lineaments obtained from geological and filtered magnetic maps shows that the major tectonic trends are NNE–SSW, NE–SW, and NW–SE, in addition to less predominant ENE–WSW and N–S trends. Two parallel shear zones trending NE–SW were detected. The causative magnetic structures were imaged at depths varying from the surface down to 2200 m. A number of strong uranium anomalies associated with Younger Granites and Dakhla, Duwi, and Quseir formations were identified which are worth being considered for further ground investigations.

Investigation of a Relation between Radiogenic Heat Production Rate (RHPR) and Land Surface Heat Temperature (LST) from Thermal Bands of ASTER and Landsat-8 (TIR-Data): Case Study of West Ras Gharib area North Eastern Desert, Egypt

In this paper, an attempt was tried to study the relation between the land surface heat temperature (LST), extracted, from the thermal emission infrared data (ASTER-TIR) and (Landsat-8-TIR) imagery and radiogenic heat production rate (RHPR) that calculated from airborne gamma-ray spectrometric data applied on west Ras Gharib area at Northeastern Desert of Egypt. The area is geologically covered mainly by Precambrian basement rocks, which are unconformably overlain by Phanerozoic sedimentary succession. The method used for extraction land surface heat temperature for both ASTER-TIR and Landsat-8-TIR images is the reference channel emissivity technique and founded as the best method comparing to others. The study results showed a relative higher RHPR threshold value reached 4.8 μW/m3. On the other hand, ASTER-TIR Land Surface Temperature (AST-LST) ranges between 27.64oC to 47.2oC and, the Landsat 8-TIR Land Surface Temperature (LS8-LST) ranges between 30.64oC to 50.68oC. Comparing all results, there were a weak relationship or to some extent parallel relation between RHPR and satellite LST; as when the value of the Y-axis is constant, there are multiple values on X-axis, so it is not possible to deduce the value of one variable in terms of the other. The poor relation is regarded to the very weak RHPR which is not enough to affect the surface heat temperature, emission that could be detected by both thermal sensors of ASTER and Landsat-8 satellite TIR data. Other factors such as: topography, wind, shading and scattering, rock moisture and density, can strongly affect the surface temperature. In conclusion, the output results could be improved in areas of very high radioelement concentrations especially 235U, and through the use of the enhanced spatial resolution of future satellite TIR imaging instruments.

Determining the age of Vaughan, a potential source crater for lunar meteorites, using boulder size-frequency distributions

We use Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images to analyze the boulder distribution around Vaughan crater, a small, fresh crater on the far side of the Moon. Using six similar lunar impact craters of known age for comparison, we determine the approximate age of the crater. Vaughan crater lies in a part of the South Pole-Aitken basin that is compositionally similar to lunar meteorite Dhofar 961, on the basis of Lunar Prospector Gamma Ray Spectrometer data, making Vaughan crater a potential candidate for the source of this meteorite and possibly others paired with it. Boulder distributions reveal that as impact craters age, the boulder population density in their ejecta decreases. This understanding allows us to use size-frequency distributions to compare crater ages on the basis of their boulder population density. We find that Vaughan crater is very young (<25 Ma) owing to its placement within the boulder size-frequency comparison plot and its population of large (>10 m diameter) boulders. Additionally, we compare LROC NAC distributions to thermophysically derived values for rock abundance from the Diviner Lunar Radiometer. We find that our LROC NAC count is consistent with Diviner rock abundance values, which further supports the inference that Vaughan is a very young impact crater and could plausibly be a source of lunar meteorite Dhofar 961.

Integrated spectral analysis of ASTER and gamma-ray spectrometric data to delineate alteration minerals for uranium exploration in Gabal Khashm El-Risha area, North Eastern Desert, Egypt

The main topic of this study is to integrate the spectral analyses of ASTER (VNIR-SWIR) with gamma-ray spectrometric data for mapping the alteration zones that affect in the distribution of the radioactive elements in Gabal Khashm El-Risha area, North Eastern Desert, Egypt. The spectral transformation techniques such as band ratios and minimum noise fraction in addition to mixture tuned matched filtering applicable to ASTER data are used to identify these altered zones. The applied techniques revealed approximately rapprochement between specific alteration minerals (i.e. hematite, goethite, muscovite, epidote, kaolinite and alunite) and the high potentiality of radioelements. The present work utilizes gamma ray spectrometric data (colored radioelements, contour maps, ratio maps and F-parameter) and correlated with the interpreted ASTER maps to allocate the possible zones of uranium mineralization. The associated abnormal level of radioactivity exhibits 10.5 and 24.2 ppm for eU and eTh respectively and mainly restricted to the syenogranites, which significantly have higher hematite content rather than the other exposures. Field-work and laboratory analysis validated the results obtained from ASTER data combined with gamma-ray spectrometric data.

Magnetic and gamma-ray spectrometric airborne geophysical data for investigating potential mineral resources and generating geoscientific knowledge in Colombia

The Servicio Geológico Colombiano has made available several airborne magnetometry and gamma-ray spectrometry datasets. The information was acquired in 15 blocks that cover approximately 520,000 square kilometers of Colombian territory, representing more than 850,000 linear kilometers of information. The data were collected along flight lines separated by 500 meters or 1000 meters, depending on the area, with sampling rates of 10 Hz (8 meters) and 1 Hz (80 meters) for the magnetometry and gamma-ray spectrometry data, respectively. The information is stored in 30 databases separated for each block and for each of the geophysical methods used. The Servicio Geológico Colombiano has provided a web portal that provides detailed specifications for each database and allows interested parties to see the terms and conditions to access the datasets and to check possible restrictions on access to information. To date, there is no geophysical database in Colombia with the coverage and resolution of these data sets, which will be very useful for geological research and research on potential mineral resources and to support geohazard monitoring, land-use planning and providing a baseline dataset for environmental monitoring.

Integrating remote and biogeochemical data: Analyzing the potential of gamma ray spectrometric data for mapping Cerrado vegetation types

This study integrates remote and chemical data to investigate the potential use of potassium (K), thorium (Th), and uranium (U) radioisotopes for mapping Cerrado physiognomies. Because soil and vegetation are interdependent, the vegetation over the substrate reflects this relationship. Moreover, the physiognomic extracts that accompany the distribution of elements associated with the movement of this substrate in soil can be identified. Gamma ray spectrometric data have been used primarily for mineral exploration; however, the present study addresses the potential of these data for identifying vegetation. Using a multivariate analysis, it is possible to compare radioisotope data and their relationship to vegetation. The current study area is located in the northwest of Goiás, an area of conserved phytophysiognomic diversity that enables studies of the Cerrado vegetation. An initial cluster analysis defined five vegetation cover types: cerradão, cerrado rupestre, cerrado sensu stricto and campo limpo. Dendrograms demonstrated a positive relationship in the radioisotopes absorbed by certain plants; furthermore, their availability in the soil confirmed that it is possible to identify vegetation groups using the same absorption behavior. This soil-plant relationship divides groups that have the capacity for the absorption of radioisotopes with remote gamma-spectrometry data. Even considering that each species might react differently because of absorption and the bioavailability of elements in the soil, a relationship between absorption and remote data was identified. Furthermore, this relationship is reflected in the physiognomy, as confirmed by a multivariate discriminant analysis. The result of the analysis showed the potential of Th and K radioisotopes with regard to phytophysiognomic mapping.

Integration of ASTER and geophysical data for delineating potential mineralization zones in Dungash-Atud area, Central Eastern Desert, Egypt

Dungash-Atud area, located in the southeastern Egyptian Desert, is intensively distinguished by gold mineralization and associated mineral deposits. This area was studied using the integrated analysis and interpretation of ASTER, aeromagnetic, and gamma-ray spectrometric data. For ASTER, different approaches of image processing, such as false color composite (FCC), ASTER-TIR indices, principal component analysis (PCA), and spectral mapping, have been used to determine the desired information on the geology, lithology reclassification, and the existing minerals, particularly older and younger granites, basic, and ultrabasic rocks. Also, the alteration imagery maps of different minerals, sericite, chlorite, illite, kaolinite, calcite, epidote, and quartz, are obtained and classified, in addition to Mafic and Quartz Index. The processed and interpreted aeromagnetic data helped effectively for the detection of the deep subsurface and near-surface structural elements affecting the area and inspection favorable sites of mineralization that give strong magnetization of which chromite bodies associated with serpentinite rocks. In addition, the aerospectrometric data, equivalent uranium eU, equivalent thorium eTh, potassium K%, and total count (TC), were analyzed and hence the ratio maps (eTh/K, eU/K, and eU/eTh) and ternary radioelement composite images were produced to infer the enriched sites of U and Th mineralization. The integration of these results was guided and tied with previous geological information, especially ancient and present gold mines and associated mineral deposits. Such results gave clear clue about the existing number of basic to ultrabasic parallel wide dikes injected within fault zones trending mainly parallel to the Red Sea rift tectonics (NW and NNW directions) and other faults/dikes, trending in the NE direction. The long-extended NW trending wide dykes are cutting across the whole investigated area reflecting its deeper extension. Other faults show lateral displacements representing major shear zones, trending mainly in the NE direction. The produced potentiality map using GIS technique showed that most of the ancient gold mines and/or associated mineral deposits are related and controlled greatly with the detected structural elements, dykes, and rock affinity. Hence, it is easy to follow other sites that could have a high potential for mineral deposits including a gold through further field investigation in coordination with the detailed ground geophysical survey.