Mineral Exploration Research Articles

A revised stratigraphic model for the ∼ 1910–1835 Ma Tanami Group, the Northern Territory, Australia: Implications for exploration targeting

The Paleoproterozoic Tanami Group of the Granites—Tanami Orogen hosts a known endowment of > 20 Moz of gold mineralization across numerous deposits. Throughout the region, host lithologies impart a first-order control on the style, grade and endowment of mineralization. However, the genetic relationship and regional distribution of three regionally correlative formations (the Dead Bullock, Mount Charles and Stubbins formations) remains enigmatic. Here, we combine lithostratigraphic analysis, lithogeochemistry, detrital zircon geochronology and geophysical observations to propose a new evolutionary model for the Tanami Group. We find that the Tanami Group was deposited in a continental back-arc basin setting and developed in four stages. Package A marked the onset of the rifting of the continental Archean basement. Sedimentary rocks within Package A are dominantly felsic in composition and display a unimodal detrital zircon age population at ∼ 2530 Ma. Package B marks the onset of mafic volcanism; consequently, volcaniclastic and sedimentary rocks within Package B display a distinct mafic geochemical signature. Detritus shed from an Archean basement persisted throughout this period, and a unimodal detrital age component at ∼ 2530 Ma persists. Package C marked the waning stages of voluminous mafic volcanism across the Tanami Basin. Sedimentary volcaniclastic rocks within Package C display a mixed mafic and felsic composition. Detrital zircon age spectra record multiple peaks at ∼ 2500, 3000 and 3350 Ma, which may reflect erosion of older Archean basement domains or changes in paleo-drainage. Package D marked a significant change in the source of detritus entering the basin from dominantly Archean to Paleoproterozoic, with dominant detrital age peaks at ∼ 1860 Ma. Despite significant lithofacies variations, the presented model highlights multiple correlations between the Dead Bullock and Mount Charles formations. The Mount Charles Formation likely represents a volcanic source-proximal, high-energy depocenter. In contrast, the Dead Bullock Formation was deposited in a lower energy setting, distal to volcanic centers. These observations are important to mineral exploration. Notably, the Mount Charles Formation is distributed over a significantly greater area than previously thought, and the under-represented Hangingwall and Footwall sequences of this formation are interpreted to host significant gold mineralization at the Oberon and Groundrush deposits.

Analysis of the Effect of Coal and Mineral Mining Safety Management System (SMKP Minerba) Implementation on the Mineral Exploration Drilling Company’s Safety Mining Performance at PT.

Background: In Indonesia, mining companies such as PT X, which has an IUJP for mineral exploration drilling, must implement SMKP Minerba. This system, which is aligned with government guidelines, includes seven elements such as Policy, Planning, Organization, Implementation, Evaluation, Documentation, and Review. Research purposes: The objective is to analyse the effect of implementing the Mineral and Coal Mining Safety Management System (SMKP Minerba) on the work safety performance of Mineral Exploration Drilling Company at PT X. Research methods: This study used a descriptive quantitative method and a case study approach, to analyse SMKP Minerba documents, including Mining Safety Performance records. Descriptive statistics, simple linear regression, and Pearson Correlation assessed variable impacts and relationships. From 144 engineers, the Slovin formula required a minimum sample of 98. Research result: The study reported that the Internal Audit of the Mineral and Coal Mining Safety Management System (SMKP Minerba) achieved a score of 84.1%. Mining safety performance was evaluated across four key indicators. Worker Participation, Leadership Responsibility, Incident Analysis and Statistics, Occupational Diseases and Incidents, and Risk Control Efforts, yielding an overall score of 0.78 out of 1, placing it in the "Planned" category. Pearson correlation analysis indicated a positive association between Position, Tenure, and SMKP Audit Scores with Mining Safety Performance. ANOVA demonstrated a significant impact of Position and Tenure on Mining Safety Performance. Conclusion: The study found that employees holding higher positions, possessing longer tenure, and achieving higher SMKP audit scores exhibited superior mining safety performance. The application of SMKP Minerba positively influences the safety performance in mining operations at PT X, contributing to the sustainable enhancement of mining safety practices in Indonesia.

Laser-Induced Breakdown Spectroscopy in Mineral Exploration and Ore Processing

Laser-induced breakdown spectroscopy (LIBS) is a type of optical emission spectroscopy capable of rapid, simultaneous multi-element analysis. LIBS is effective for the analysis of atmospheric gases, geological fluids, and a broad spectrum of minerals, rocks, sediments, and soils both in and outside the traditional laboratory setting. With the recent introduction of commercial laboratory systems and handheld analyzers for use outside the laboratory for real-time in situ analysis in the field, LIBS is finding increasing application across the geosciences. This article first overviews the LIBS technique and then reviews its application in the domain of mineral exploration and ore processing, where LIBS offers some unique capabilities.

Geological controls of mineralization occurrences in the Egyptian Eastern Desert using advanced integration of remote sensing and magnetic data

This study presents a comprehensive analysis of mineralization exploration in the Egyptian Eastern Desert (ED), one of the most sought-after areas for those interested in mining industry, by integrating Landsat-9 images and geophysical magnetic data. Employing advanced techniques like Principal Component (PC) analysis, Minimum Noise Fraction (MNf) transform, and Band-Ratio (B-Ratio), the research focuses on mapping lithological units, hydrothermal alteration regions, and structural elements. Composite images derived from specific PC, and MNf bands, and B-Ratio exhibit superior lithological unit identification. The findings emphasize that there are significant variations in the types of rocks extend from the southern to the northern parts of the ED. Hydrothermal alteration mapping, guided by B-Ratio results, aids qualitative lithological discrimination. A novel false color composite image optimizes Landsat-9 B-Ratios, enhancing rock unit discrimination. Correlation analyses reveal associations between mineralization types and major lithological units, while exploration of the magnetic anomaly map highlights its role in correlating mineralization sites. Structural features, analyzed through Center for Exploration-Targeting Grid-Analysis (CET-GA) and Center for Exploration-Targeting Porphyry-Analysis (CET-GA) with Tilt Derivative of RTP (TDR) techniques, contribute to a robust association between regions with medium to high structural density and porphyry intrusions and mineralization. The study significantly supports the advanced exploration geoscience, providing insights into the geological structures and dynamics governing mineralization in the Egyptian ED.

Magnetotelluric imaging of an iron-oxide copper gold (IOCG) deposit under thick cover

The presence of thick (>100 m) and electrically conductive (< 10 Ω.m) ground cover is a major impediment in mineral exploration of deep resources. Iron-oxide copper gold (IOCG) systems in Australia are often associated with a pronounced potential field anomaly, depending on the oxidation state of iron, but the gravity and magnetic field signatures have little vertical resolution unless constrained by drill hole petrophysics. Additionally, IOCG systems have deep magmatic sources, with their conductivity anomalies extending at least to the lithospheric mantle. The Vulcan IOCG prospect lies about 30 km northeast of the Olympic Dam IOCG mine and is defined by a significant gravity anomaly associated with brecciated haematite beneath 850 m of sedimentary cover sequences. To image the physical properties and structural geometry of the Vulcan IOCG prospect, a 100-site broadband MT and passive seismic array was deployed in a 1 km grid over a 9 by 9 km area. Three-dimensional inversion of MT responses resolve structure in three distinct domains. Firstly, broad limestone-quartzite-shale stratigraphy (1–30 Ω.m) in the 850 m cover is delineated in resistivity and corresponds well with changes in shear-wave velocity. Secondly, the region of brecciated haematite below the cover sequences is shown to have lower resistivity (< 60 Ω.m) than surrounding country rock (> 100 Ω.m). Thirdly, a more electrically conductive (< 30 Ω.m) vertical zone that extends > 5 km is imaged a few kilometers to the northeast of the Vulcan haematite breccia, and appears to be linked by a region of low shear-wave velocity in the depth range 1–2 km. Two-dimensional inversion of more regional MT responses along a 200-km line passing through the Vulcan prospect suggest this vertical region of low resistivity links to the lower-crust with anomalous resistivity of < 60 Ω.m in a similar way as imaged beneath the Olympic Dam mine. It is suggested that this conductive region is associated with graphite precipitated from magmatically derived CO2-rich fluids cooling in a reducing environment.

Assessment of Ecological Quality and Analysis of Influencing Factors in Coal-Bearing Hilly Areas of Northern China: An Exploration of Human Mining and Natural Topography

The Changhe Basin is located in the earth–rock mountainous area in southeastern Shanxi, China, and represents a characteristic northern coal-bearing hilly area. The terrain is complex, and the area is rich in coal mines. It plays an indispensable role in maintaining ecological balance and sustainable development in North China. To investigate the changes in ecological quality in the Changhe Basin, as well as the impact of human mining activities and natural topography on ecological quality, this study constructs the Remote Sensing Ecological Index (RSEI) based on Landsat remote sensing images from 2001, 2008, 2015, and 2022, undertaking an analysis of the spatial–temporal distribution characteristics of the ecological quality and its changing trends over the past 20 years. Additionally, spatial autocorrelation distribution features are revealed using Moran’s I. The exploration extends to examining the relationship between mining activities and the surrounding ecological quality. Subsequently, we study the relationship between Topographic Wetness Index (TWI) and RSEI. The results indicate the following: (1) On the temporal scale, the average proportion of RSEIs categorized as excellent and good from 2001 to 2022 is 46.78%. Types showcasing stable ecological conditions average 52.49%. The level of overall ecological quality of the basin has remained consistently high. On the spatial scale, the western part of the Changhe River, particularly in mountainous areas, exhibits higher ecological quality. Poorer areas concentrate in Chuandi Town in the southwestern part, and are significantly impacted by mining activities. The eastern region manifests areas undergoing either rapid or gradual degradation. (2) The four-phase Moran index results reveal a robust positive correlation in the spatial distribution of ecological quality within the basin. High–High and Low–Low clusters dominate, while High–Low and Low–High distributions are scattered. (3) Mining activities exert a discernible impact on the surrounding ecological quality. As the distance from the buffer zone outside the mining area increases, RSEI gradually decreases. The impact level exhibits an initial increase and subsequent decrease from 2001 to 2022.

A Review of Integration Techniques of Multi-Geoscience Data-Sets in Mineral Prospectivity Mapping

In every sphere and utility aspects of human life, there is need of metals and construction materials. Minerals which are below the near subsurface is almost explored on the basis of direct geospatial evidences. There is high demand of metals and other materials which are mined below the surface of earth In the current landscape, there&amp;apos;s a demand for faster and more precise exploration strategies, particularly emphasizing Greenfield exploration and deep-seated mineralization. This paper conducts a comprehensive review of existing methodologies for integrating multi-geoscience datasets aimed at mineral prognostication, with a focus on identifying the most precise and authentic Artificial Intelligence (AI) - based data integration techniques. Additionally, it offers insights into the current status of mineral exploration in India and the global evolution of data integration practices. Several types of geoscientific datasets i.e. geological, geophysical, geochemical and geospectral data have to be organized in geospatial domain for meaningful mineral exploration outcome. These datasets have been processed to extract exploratory indicator layers for data integration are called Mineral Prospectivity Mapping (MPM). Indeed, MPM is a multiple criterion decision making (MCDM) task which provide a predictive model for categorizing of sought areas in terms of ore mineralization. There after based upon Geological factors i.e. lithology, structure, shear &amp; fault zones, alteration zones etc. of sought mineralized area, selection of drilling parameters (depth, angle, level, type, rpm, feed) is done for resource assessment. Literature survey suggests that minerals exploration by integrated approach on the basis of these datasets is still poorly performed. It has been gathered that knowledge-driven data integration using Fuzzy Gamma Operator and Multiclass Index Overlay method is best suited for mineral exploration. In past, few researchers of other countries have exploited data integration approach with encouraging results. Despite the abundance of data available in India, this approach has not been utilized very successfully and no standard protocols exist even for decision making for drilling operation. Thus, it&amp;apos;s evident that employing the Fuzzy Inference System (FIS) algorithm, particularly utilizing the Fuzzy Gamma Operator and Multiclass Index Overlay integration method, remains underutilized in designing standardized operating procedures (SOP) for mineral exploration in India and decision-making for drilling operations. This approach holds promise for minimizing time lag and optimizing resources such as manpower, instruments, and finances.

Domain Adaptation from Drilling to Geophysical Data for Mineral Exploration

This study utilizes domain adaptation to enhance the integration of diverse geoscience datasets, aiming to improve the identification of ore bodies. Traditional mineral exploration methods often face challenges in merging different geoscience data types, which leads to models that do not perform well across varying domains. Domain adaptation is a deep learning strategy aimed at adapting a model developed in one domain (source) to perform well in a different domain (target). To adapt models trained on detailed, labeled drilling data (source) to interpret broader, unlabeled geophysical data (target), Domain-Adversarial Neural Networks (DANNs) were applied, chosen for their robust performance in scenarios where the target domain does not provide labels. This approach was indirectly validated through the minimal overlap between regions identified as candidate ore and borehole locations marked as host rocks, with qualitative validation provided by t-Distributed Stochastic Neighbor Embedding (t-SNE) visualizations showing improved data integration across domains.

Hotspot–subduction zone interactions and their resource effects at ∼120 Ma on the central Tibetan Plateau

The central Tibetan Plateau, particularly the Bangong–Nujiang suture zone, hosts abundant and complex Late Mesozoic geological records and world-class mineral resources. However, intense debate persists about the origin and tectonic setting of these geological records and mineral resources, which impedes a comprehensive understanding of regional Late Mesozoic tectonic evolution and mineralization. In this study, we investigated the petrochronology, geochemistry, and Sr-Nd-Hf isotopic characteristics of ∼120 Ma magmatic rocks in this region. We explored their petrogenesis and sources, and in conjunction with their spatiotemporal distribution and scale, we facilitated a first proposal that these magmatic rocks were derived from ∼120 Ma hotspot–subduction zone interaction and that world-class mineral deposits were formed in this geological setting. This study is the first to identify geological records of hotspot–subduction interaction in the central Tibetan Plateau and it has significant implications for gaining a deeper understanding of the closing processes of the Late Cretaceous Epoch in the Meso-Tethys Ocean. This study also highlights the substantial contribution of this hotspot–subduction zone interaction to the formation of world-class mineral deposits in the region, and thus has crucial significance for guiding mineral exploration in the central Tibetan Plateau.

Integrating soil geochemistry and machine learning for enhanced mineral exploration at the dayu gold deposit, south China block

Combining traditional geochemical methods with advanced analytical techniques is a hallmark of contemporary exploration efforts. This study explores the intricate geological dynamics of the Dayu gold deposit, located in the Dayao Uplift of the South China Block. Using a multidisciplinary approach that includes soil geochemistry, conventional geochemical methods and advanced computational techniques such as machine learning and Discriminant Projection Analysis (DPA), we aim to uncover the deposit formation information. Our results reveal a complex pattern of element anomalies, which serve as a geochemical fingerprint of the Au mineralization processes that shaped the deposit over geological time. Principal Component Analysis (PCA) and cluster analysis on soil samples highlight significant correlation among Au and its pathfinder elements. By leveraging the predictive capabilities of machine learning algorithms, particularly Convolutional Neural Networks (CNN), we improve exploration strategies, enhance the precision of target delineation and guide sampling efforts. DPA further identifies distinct discriminant functions, aiding in group differentiation and providing insights into prospective mineralization zones. This study exemplifies the integration of traditional and innovative methodologies, offering a pathway to a deeper understanding of mineralization processes and improving the effectiveness of exploration in complex geological terrains. The findings advance our knowledge of the Dayu gold deposit and demonstrate the potential of these integrated approaches in similar geological settings.

Enhancing deep orebody prediction and localization through the revelation of geochemical primary halo patterns in drill holes

Geochemical primary halos play a crucial role in mineral exploration as they provide valuable insights into the dispersion of ore materials, identification of concealed deposits, and determination of ore deposit dimensions. The Naruo mining area in the Duolong mineral district, northern Tibet, China well-known for its worldclass porphyry-epithermal Cu–Au deposits is currently chosen as the study area. We employ statistical and nonlinear methods to analyze geochemical data from drill holes. Specifically, R-type cluster analysis is utilized to evaluate element affinity and concentration index, while an improved Grigorian zoning index is employed to delineate the vertical zoning sequence of the primary halo. These methodologies significantly enhance our understanding of element enrichment within geological contexts and greatly contribute to mineral resource evaluation. Based on these results, we have constructed a vertical zonation index model of denudation coefficient tailored to the geological characteristics of mineralization within the study area. This model effectively represents the vertical variation of the ore body. Our findings reveal a decrease in this zoning index towards the central region of deep ore bodies which correlates with deep granodiorite porphyry occurrences. Furthermore, we observe increasing concentrations of Cu, Ag, and Au with depth in specific sections of drill holes indicating promising exploration potential. Supplementary short-wave infrared data suggests the presence of a deep hydrothermal center in drill hole RNZK2404 which tentatively infers concealed porphyry bodies. Notably, the reversal observed at 4200 m on RNZK2404's zoning index hints at a possible hidden ore body at great depths. Finally, three-dimensional visualization techniques effectively illustrate spatial patterns for elements thereby paving way for future endeavors in mineral exploration.

A Preliminary Study: Physicochemical Characteristics and the Recommendations for Industrial Application of the Mlaten Clay Materials, Mojokerto, East Java, Indonesia

Abstract Clays are industrial minerals that are widely utilized for various industrial fields. Eastern Java has a high potential of clay minerals (±348 million tons), including Mojokerto. The research location is in Mlaten and its surroundings, Mojokerto, East Java and covers an area of ± 16 km2. The massive utilization and potential in this area has not been comprehensively followed by research and exploration of clay minerals. In this case, the potential of clay minerals needs to be investigated so that prospective locations can be determined along with recommendations for optimal utilization. To determine the physical properties, which are plasticity test, grain size test, and forming water test, were conducted on 3 samples of raw clay and 1 sample of industrial clay. Furthermore, the geochemical analysis is to determine the major oxide compounds and was conducted on 8 raw clay samples. The lithology units of the study area can be divided into 2 units, consisting of sand-clay unit and weathered upper Quaternary volcanic unit. The Mlaten clay deposits are found in both units. Physical characteristics of clay in Mlaten are consisting of 2,34% - 2,47% clay grain size and having of moderate to high plasticity. The recommendation for forming water in clay utilization ranges from 15-43%. On the other side, Mlaten clay is geochemically characterized by high content of SiO2 (50-59,6%), Fe2O3 (7,24-10,15%), and Al2O3 (16,9-19,9%), but low content of K2O (0,63-1,04%), Na2O (1,44-2,49%), MgO (1,04-1,96%), and CaO (2,42-4,87%). Based on the physicochemical characteristics, Mlaten clay are recommended as raw materials for the manufacture of earthenware ceramic industry, cement industry, and as absorbents in the palm oil industry.

Geochronology and geochemistry of granites from the Longhua Ni-Co deposit, South China: Implication for the formation of Ni-Co mineralization

Mineral exploration activities since 2010 in a previously poorly explored region of northeastern Guangxi province, South China, confirmed the existence of a potentially large hydrothermal Ni-Co deposit. As a newly discovered deposit, many aspects of this deposit are still unclear, including in which tectonic setting the deposit formed and how the high-grade mineralization developed. To address these questions, in this study, we conduct a comprehensively geochronological and geochemical study on the Dajin pluton (consisting of biotite monzogranite and sericitized monzogranite), which is the only pluton occurring in the district. LA-ICP-MS zircon U-Pb dating shows that two types of granites were emplaced nearly at the same time, with biotite monzogranite and sericitized monzogranite being 449 ± 15 Ma and 448.4 ± 8.8 Ma, respectively. This, combined with previously published studies, confirms that the Dajin pluton was broadly emplaced during the formation of the Longhua deposit. These granites are characterized by high K2O, and noticeable depletion of Eu, Sr, P and Ti, with whole-rock εNd(t) values ranging from −1.99 to −4.26 and zircon εHf(t) values ranging from −0.9 to 4.1. These features support that the studied granites are typical of A2-type granites, which experienced strong fractional crystallization and formed in a post-collisional environment. Although Co and Ni might not have been originally derived from granitic magmas, we suggest that the emplacement of the Dajin pluton facilitated the formation of high-grade Ni-Co mineralization in two ways: (1) melting the Co– and Ni-enriched mafic basement probably existing in the deep crust, and (2) remobilizing and concentrating metals from wall rocks.

Primary Controlling Factors of Apatite Trace Element Composition and Implications for Exploration in Orogenic Gold Deposits

AbstractSignificant and readily accessible orogenic gold deposits have been previously recognized, exploited, and progressively depleted. Innovative approaches are required to discover new and deeply buried deposits. Recently, trace element variations in apatite have been used to distinguish fertile and barren environments as reliable mineral exploration tools. In this study, machine learning models using Random Forest and Deep Neutral Network are utilized to assess the fertility of quartz veins and altered zones in the orogenic gold systems. The two models have been trained using trace element data of apatite, and the performance of both models yield good classification accuracy (∼90% on average) with low false positive rates. Feature importance analysis (Gini decrease and hidden layer weights) suggest that Pb, As, U, Sr, Eu, Mn, and Fe are the important parameters. Arsenic, U, Eu, Mn, and Fe are redox‐sensitive elements, with their concentrations responding to changes in fluid redox conditions. Strontium primarily originates from the breakdown of plagioclase, which is more likely to occur under oxidizing fluid conditions. Therefore, we infer that the main controlling factor of the models is the redox conditions. The two distinct models consistently highlight the most significant contribution of Pb to this differentiation, even though Pb is not a redox‐sensitive element and can only substitute for Ca2+ in apatite as Pb2+. We infer that the high contribution of Pb may be attributed to the potential transportation of Au in the form of a Pb‐(Bi)‐Au melt, and the Pb content in apatite is influenced by the Pb content in the melt, fluid oxygen, and sulfur fugacity. We also propose a novel discriminant plot using Linear Discriminant Analysis (LDA) to assess the mineralization potential in quartz veins and alteration zones based on apatite trace element data. The machine learning and LDA results suggest that apatite trace elements could be used effectively in the future orogenic gold deposit exploration.

Integration of Large Multielement Geochemical, Aeromagnetic, and Gravity Data to Geologically Map a Largely Covered Area: A Case Study from the Central African Copperbelt in Northern Zambia

Abstract This study provides a method to map lithology, stratigraphy, and structures in areas with limited outcrop using mineral exploration data from multielement soil geochemical surveys, airborne and ground geophysical surveys, and drill hole data sourced from multiple exploration companies and campaigns. The 45- by 50-km study area is located in the southern portion of the Congolese Copperbelt, where the regional geology, structure, and overall basin architecture were not well understood, partly due to thick saprolite cover. The results demonstrate that the integration of such data sets allows the creation of a geologically coherent map, which can then be used to investigate basin architecture and identify basin-forming structures.

Supergene Oxidized Gold-Silver Deposits in the Americas: Guides for Geologists

Editor’s note: The aim of the Geology and Mining series is to introduce early career professionals and students to various aspects of mineral exploration, development, and mining in order to share the experiences and insight of each author on the myriad of topics involved with the mineral industry and the ways in which geoscientists contribute to each. Abstract Supergene oxidation is a process that has created some of the largest gold and silver orebodies in the Americas, including the Carlin-type (sediment-hosted) gold deposits and Round Mountain in Nevada; Yanacocha and many similar deposits in Peru; Cerro Rico, Bolivia; and Pueblo Viejo, Dominican Republic. Oxidation can make sulfide-bearing gold-silver deposits economic by converting refractory gold-silver–bearing sulfide minerals to minerals that can be leached by dilute cyanide solutions. The use of cyanide heap leaching or tank leaching enabled open-pit mining of low-grade oxidized gold deposits starting in the 1960s. This revolutionized gold mining which, combined with the end of the dollar gold standard in 1971, led to a huge increase in gold production, particularly in the Americas where the technology has been widely applied. During weathering and oxidation of sulfide minerals, particularly pyrite, associated gold and silver form supergene minerals in the oxidation zone but are only transported over short distances (centimeters to meters) due to low solubility of the metals, so they do not form enrichment zones. Gold forms Au0 grains of 1 to 25 µm size and high fineness, as well as invisible gold associated with jarosite and iron oxyhydroxides by sorption or substitution. Silver forms halides and native silver, which may be accompanied by metastable hypogene acanthite. Silver in jarosite, alunite, and Mn oxides is refractory. The economic advantages of near-surface oxidized deposits are that they can be mined by open pit with low costs, commonly not requiring stripping or blasting. Run-of-mine ore is sent directly to leach pads, although some ores may require prior crushing and grinding with agglomeration of fine material such as clays. Oxidized ore is processed by heap leaching using dilute sodium cyanide solution and gold and silver recovered by zinc cementation or on activated carbon. Some ores require grinding and are processed by tank leaching. The hypogene sulfide minerals below the oxidized zone are typically refractory and require at least ultrafine grinding for leaching to be effective, or high-cost oxidation technology for roasting, autoclaving, or bio-oxidation. The sulfide-rich portions of deposits are often not exploited for many decades after discovery, if at all. To explore for supergene oxidized deposits, the exploration geologist requires knowledge of geology, oxide mineralogy, geomorphology, hydrogeology, and the (paleo)-climate, as well as open-pit mining, hydrometallurgy, cyanide leaching, and carbon technology, topics that are introduced here with case studies.

Integrating multispectral remote sensing and geological investigation for gold prospecting in the Borongo-Mborguene gold field, eastern Cameroon

Multispectral remote sensing data has great promise for mineral prospecting via regional-scale mapping of alteration zones and geological structures, once the method is calibrated using in-situ geological observations. The Borongo-Mborguene area, located in eastern Cameroon at the transition from sub-tropical to arid climates, hosts several alluvial gold deposits. In this investigation, maps developed by processing of Landsat-8 OLI images, ASTER satellite images, and SRTM DEM data were compared to results of a comprehensive field survey to locate zones of hydrothermal alteration and regional structural lineaments, and to verify the association of these features with gold mineralization. Specific Landsat-8 and ASTER band ratios, as well as principal component analysis of the multispectral images, were selected to isolate spectral signals that characterize particular groups of alteration minerals, such as clays, hydrated carbonates, hydrated sulphates, iron oxides, and iron hydroxides. Lineaments and their preferred orientations were extracted by filtering of the digital elevation data. A fuzzy logic approach was subsequently applied to the ensemble of resulting maps to highlight five areas of concentrated hydrothermal alteration and structural complexity as potential gold prospects (Mborguene, Boutila, Nandoungue, Borongo and Ouaden villages). Petrographic study of samples collected from the remotely-identified alteration zones revealed a hydrothermal ore assemblage of gold, galena, pyrite and hematite in mineralized quartz veins. Structural control of the alteration zones in the Borongo-Mborguene gold field was confirmed by field mapping along a shear zone. Hence, our petrographic and field studies indicate that the multispectral remote sensing data and data processing methods developed herein are appropriate for mineral exploration in remote sub-tropical areas of Africa. More generally, the computationally efficient and simple procedure developed here should yield accurate preliminary maps of the spatial distribution of hydrothermal halos and related mineral deposits in challenging mixed-type vegetated terrain around the globe.

What Extra Information Can Be Provided by Multi-Component Seismic Data: A Case Study of 2D3C Prospecting of a Copper–Molybdenum Mine in Inner Mongolia, China

With the decrease in shallow mineral reserves, deep mineral resources have become the focus of exploration. Seismic exploration, renowned for its deep penetration and high spatial resolution and precision, stands as a primary technique in geophysical exploration. In comparison to traditional P-wave seismic exploration, multi-component seismic techniques offer the advantage of simultaneously acquiring P-wave and S-wave data, overcoming the limitations of single P-wave impedance in predicting lithology and enabling high-precision imaging of subsurface structures. Constrained by field survey costs, the reflection seismic illumination is lower and results in a poor signal-to-noise ratio of multi-component seismic data in metallic ore exploration, which poses great challenges in imaging converted S-waves. Based on the seismic and geological characteristics of metallic ores, this study conducts imaging research on metallic ore models through synthetic data and field multi-component seismic data from a copper–molybdenum mine in Inner Mongolia, China. The emphasis is given to PS-wave pre-stack time migration based on precisely sorting the commonly converted point so as to explore the feasibility and technical advantages of multi-component seismic exploration in metal mines. Synthetic data and field data testing demonstrate that PS-wave imaging contains more abundant structural and lithological information compared to PP-waves, indicating promising prospects for the application of multi-component seismic data in metallic ore exploration.

Integrated Geophysical Investigation for Potential Gold Mineralised Zone within Lower Part of Zuru Schist Belts, NW Nigeria

The study began with a reconnaissance survey that used high-resolution aeromagnetic data of the study area to identify suitable structure zones with the potential to trap mineral resources within the context of the gold exploration target. The findings of magnetic studies were followed up with detailed investigations using 2D electrical resistivity tomography (ERT) and induced polorisation (IP) techniques to reveal further details about gold mineral zones and other lithological boundaries. The airborne magnetic data of sheet 118_Yelwa was obtained from the NGSA; these datasets were processed and analyzed using Oasis Montaj's first vertical derivative (FVD) and center for exploration targeting (CET) techniques. Results of FVD and CET grid anomalies show that regions of major magnetic structures (lineaments) are associated with granite gneiss, migmatitic augen gneiss, and medium to coarse-grained biotite when compared to the geological settings of the area. The zones of major structures obtained in this study coincided with previous magnetic studies of the area, located in the eastern parts of Ngaski, Yauri (Yelwa), Shanga, Agwara, as well as Magama's northwest region. Some of the regions for lineament (in the eastern part of Ngaski/Yauri) were investigated further with 2D ERT and IP detailed geophysical methods in a dipole-dipole configuration. The results of geoelectric techniques along profiles 1, 2, and 3 identified the major gold mineralisation potential zones, which were labeled A1, A2, and A3. These regions have low/high resistivity (1.6 to 459 Ωm/1889 to 7773 Ωm) and chargeability signatures (≥ 20 msec), and could thus be interpreted as potential target zones for metallic mineral exploration, particularly gold mineralisation. The regions are located in the northern Mararraba and southwest of the Jinsani areas of Kebbi State. The results of integrated geophysical methods have produced updated structural features of the regions, as well as a database containing precise locations, lateral lengths,...

Integrated Geophysical Investigation for Potential Gold Mineralised Zone within Lower Part of Zuru Schist Belts, NW Nigeria

The study began with a reconnaissance survey that used high-resolution aeromagnetic data of the study area to identify suitable structure zones with the potential to trap mineral resources within the context of the gold exploration target. The findings of magnetic studies were followed up with detailed investigations using 2D electrical resistivity tomography (ERT) and induced polorisation (IP) techniques to reveal further details about gold mineral zones and other lithological boundaries. The airborne magnetic data of sheet 118_Yelwa was obtained from the NGSA; these datasets were processed and analyzed using Oasis Montaj's first vertical derivative (FVD) and center for exploration targeting (CET) techniques. Results of FVD and CET grid anomalies show that regions of major magnetic structures (lineaments) are associated with granite gneiss, migmatitic augen gneiss, and medium to coarse-grained biotite when compared to the geological settings of the area. The zones of major structures obtained in this study coincided with previous magnetic studies of the area, located in the eastern parts of Ngaski, Yauri (Yelwa), Shanga, Agwara, as well as Magama's northwest region. Some of the regions for lineament (in the eastern part of Ngaski/Yauri) were investigated further with 2D ERT and IP detailed geophysical methods in a dipole-dipole configuration. The results of geoelectric techniques along profiles 1, 2, and 3 identified the major gold mineralisation potential zones, which were labeled A1, A2, and A3. These regions have low/high resistivity (1.6 to 459 Ωm/1889 to 7773 Ωm) and chargeability signatures (≥ 20 msec), and could thus be interpreted as potential target zones for metallic mineral exploration, particularly gold mineralisation. The regions are located in the northern Mararraba and southwest of the Jinsani areas of Kebbi State. The results of integrated geophysical methods have produced updated structural features of the regions, as well as a database containing precise locations, lateral lengths,...