Semi-automated geological mapping and target generation from geochemical and magnetic data in Halkidiki region, Greece

This study focuses on using multivariate analyses to generate semi-automated geological maps and exploration targets associated with porphyry Au-Cu mineralization within the Kassandra mining district, Greece. We use principal component analysis (PCA) and self-organizing maps (SOM) to reveal variations in geochemical and magnetic signatures within the input datasets. We visualize the results as pseudo-geological maps reflecting the associated geological processes and their end products. In specific, we utilize the potential of these two methods through an integrated interpretation and comparison of the results. We test the validity of the unsupervised PCAand SOM-derived lithological and prospectivity models by comparing them with existing geological observations and interpretations. The results of this investigation show that both PCA and SOM are able to reproduce the key features of existing geological observations within the study area, but more importantly, also provide useful information that can be used to recognize prospective geological units and exploration targets from previously unknown locations.Peer reviewe

Critical metals in Iran – geochemistry: exploration and analysis

Critical metals are fundamental to many 21st century processes and technologies. These elements are essential for maintaining and improving future quality of life, including many high-technology yet low-carbon industries. Two factors have been used by the NRC (National Research Council) to rank criticality: the degree to which a commodity is essential and the risk of supply disruption for the commodity (Verplanch and Hitzman, 2016). The European Union has identified twenty critical raw materials as critical metals (Ec, 2015). Many of these critical materials (including Rare Earth Elements (REEs), Platinum Group Elements (PGEs), Magnesium, Niobium, Germanium, Indium, Gallium, Cobalt, Borate, Tungsten, Fluorspar are important for high-technology, environmental protection and military applications, but vulnerable to politically or economically driven fluctuations in supply (Pirajno, 2009; Laznicka, 2010; Charalampides et al., 2015; Fernandez, 2017). Tin, Molybdenum and Lithium) are included as critical metals by several countries (e.g. Australia; Skirrow et al., 2013). Of course a number of other metals, which have not been assessed as critical, are also of significant importance for modern technologies – these include some of the alloy metals such as chromium, nickel and molybdenum

GEMAS: source, distribution patterns and geochemical behaviour of Ge in agricultural and grazing land soils at European continental scale

Agricultural soil (Ap-horizon, 0-20 cm) and grazing land soil (Gr-horizon, 0-10 cm) samples were collected from a large part of Europe (33 countries, 5.6 million km2) as part of the GEMAS (Geochemical Mapping of Agricultural and grazing land Soil) soil mapping project. GEMAS soil data have been used to provide a general view of element mobility and source rocks at the continental scale, either by reference to average crustal abundances or to normalized patterns of element mobility during weathering processes

Semi-automated geological mapping and target generation from geochemical and magnetic data in Halkidiki region, Greece

This study focuses on using multivariate analyses to generate semi-automated geological maps and exploration targets associated with porphyry Au-Cu mineralization within the Kassandra mining district, Greece. We use principal component analysis (PCA) and self-organizing maps (SOM) to reveal variations in geochemical and magnetic signatures within the input datasets. We visualize the results as pseudo-geological maps reflecting the associated geological processes and their end products. In specific, we utilize the potential of these two methods through an integrated interpretation and comparison of the results. We test the validity of the unsupervised PCAand SOM-derived lithological and prospectivity models by comparing them with existing geological observations and interpretations. The results of this investigation show that both PCA and SOM are able to reproduce the key features of existing geological observations within the study area, but more importantly, also provide useful information that can be used to recognize prospective geological units and exploration targets from previously unknown locations

GeoERA Raw Materials Monograph : the past and the future

ABSTRACT: GeoERA Minerals projects have produced data aimed at supporting Europe’s minerals sector and to assist the European Commission to realise its goals for raw materials. Data has been compiled on mineral occurrences and mineral provinces across Europe, in particular, areas with potential to host Critical Raw Materials. Anecdotal evidence from the minerals sector provides an indication of the likelihood of exploration leading to mine development. For every 1,000 mineral showings examined, only 100 may receive further exploration work and of those 100, only 10 may warrant more detailed sampling either through trenching, drilling or other means and of those 10 only 1 may proceed to an evaluation through a full feasibility study which itself has only 50% chance of being positive. Following this, any project for which a mine proposal is made must undergo a full evaluation and permitting by authorities including full public consultation. The proposal may or may not pass this scrutiny. In terms of a schedule, the generally accepted minimum time frame from discovery to production is 10 years and usually much more, up to 20 years.info:eu-repo/semantics/publishedVersio

Application of fractal models to characterization and evaluation of vertical distribution of geochemical data in Zarshuran gold deposit, NW Iran

Vertical distribution of geochemical data can provide useful information and appropriate criteria for recognition and classification of mineralized and non-mineralized zones. In this study, several fractal models including box-counting, power-law frequency and new Hurst exponent visual basic application (VBA) programming were applied to evaluate the continuity and irregularity of the Au mineralization, the characterization of the vertical distribution and identification of new exploration targets based on the 40 mineralized and non-mineralized boreholes in the Zarshuran gold deposit. The results of the box-counting method showed that the vertical distribution of the Au values in these boreholes exhibit self-similarity, with the values of box-dimension (Bd) ranging from 1.01 to 1.7. The Bd values indicated that all the boreholes have irregularities in the vertical distribution of the Au values. Power-law frequency results indicate that the vertical distribution of Au in the boreholes exhibit bi- and mono-fractal properties. The bi-fractal properties of the boreholes imply the multiple mineralization phases in the Zarshuran deposit. Fractal dimensions vary from 0.6 in the non- and weakly mineralized zones, to 3.4 in the mineralized zones. The large fractal dimensions of the mineralization showed more homogeneity within the mineralization. The Hurst exponent shows the homogeneous distribution of Au in the mineralized and non-mineralized boreholes. The values of the Hurst exponent range from 0.63 to 0.92, with R2 greater than 0.8, indicating good vertical distribution in the study area. The Au values for non-mineralized boreholes such as [A4] are greater than 0.5, which shows the homogeneous distribution of Au in the wall rocks. The interpolated maps of the Au mean grades, the coefficient of variation of the Au grades, Bd, dimension (D), Hurst exponents as independent variables, and the combination variable (‘H + Bd’) were utilized to predict the potential exploration targets at the surface. The results show that the zone of approximately the old arsenic mining (the main mine valley) and the Mal Darrassi Valley isthe main potential exploration targets in the Zarshuran mining district

Geochemical anomaly recognition of rare earth elements using multi-fractual modeling correlated with geological features, Central Iran

The aim of this paper is the geological studies and delineation of geochemical anomalies of lanthanum (La), cerium(Ce) and yttrium(Y) rare earth elements (REEs) in Saghand area, Central Iran. In order to recognize themineralization zones considering their concentrations, the results of the sampled litho-geochemical data were processed by concentration–area (C–A) fractal model. The C–A log-log plots of the elements were generated and their thresholds were identified. Therefore, the high intensive geochemical anomalies of the studied elements were discriminated. A part of their high intensive geochemical anomalies are situated in the west of the study area occurred within the metasomatic, porphyry microdioritic and acidic volcanic rocks associated with epidotic alterations. The other high intensive geochemical anomalies of Ce and Y are located in the center of the study area. In addition, themoderate anomalies of La and Cewere located in themetasomatic units associated with epidote and chlorite alterations in the central part of the study area. The SE parts of the Cemoderate anomalies are probably related to basic dykes associating with epidotic alterations which are situated between metasomatic and microdioritic units. Based on the results obtained from multi-fractal modeling, the locations of the main anomalies of La, Ce and Y were recognized which all are in the western, central, southern, and SE parts of the study area. Several high and moderate concentration anomalies obtained from the C–A model were confirmed by ground surveying and compared with the achieved result from remote sensing investigation. According to the correlation between geological particulars and obtained REEs anomalies, it has been proved that the proper and promising areas are in metasomatite rock units, chlorite and epidote alterations in the western and central part of the study area. By Scanning Electron Microscope (SEM) studies of davidite and uraninite minerals,it was determined that the REEs mineralization in this area have taken place mostly in the formof replacement in radioactive elements uranium(U) and thorium(Th). The combination of the field observations and mineralogical studies based on the type of REEs mineralization in the study area revealed that one of themain factors controlling the mineralization is related to metasomatism

Geochemistry of Rare Earth Elements in Bedrock and Till, Applied in the Context of Mineral Potential in Sweden

The Rare Earth Element (REE) mineralizations are not so “rare” in Sweden. They normally occur associated and hosted within granitic crystalline bedrock, and in mineral deposits together with other base and trace metals. Major REE-bearing mineral deposit types are the apatite-iron oxide mineralizations in Norrbotten (e.g., Kiruna) and Bergslagen (e.g., Grängesberg) ore regions, the various skarn deposits in Bergslagen (e.g., Riddarhyttan-Norberg belt), hydrothermal deposits (e.g., Olserum, Bastnäs) and alkaline-carbonatite intrusions such as the Norra Kärr complex and Alnö. In this study, analytical data of samples collected from REE mineralizations during the EURARE project are compared with bedrock and till REE geochemistry, both sourced from databases available at the Geological Survey of Sweden. The positive correlation between REE composition in the three geochemical data groups allows better understanding of REE distribution in Sweden, their regional discrimination, and genetic classification. Data provides complementary information about correlation of LREE and HREE in till with REE content in bedrock and mineralization. Application of principal component analysis enables classification of REE mineralizations in relation to their host. These results are useful in the assessment of REE mineral potential in areas where REE mineralizations are poorly explored or even undiscovered

Geochemical anomaly recognition of rare earth elements using multi-fractal modeling correlated with geological features, Central Iran

The aim of this paper is the geological studies and delineation of geochemical anomalies of lanthanum (La), cerium (Ce) and yttrium (Y) rare earth elements (REEs) in Saghand area, Central Iran. In order to recognize the mineralization zones considering their concentrations, the results of the sampled litho-geochemical data were processed by concentration–area (C–A) fractal model. The C–A log-log plots of the elements were generated and their thresholds were identified. Therefore, the high intensive geochemical anomalies of the studied elements were discriminated. A part of their high intensive geochemical anomalies are situated in the west of the study area occurred within the metasomatic, porphyry microdioritic and acidic volcanic rocks associated with epidotic alterations. The other high intensive geochemical anomalies of Ce and Y are located in the center of the study area. In addition, the moderate anomalies of La and Ce were located in the metasomatic units associated with epidote and chlorite alterations in the central part of the study area. The SE parts of the Ce moderate anomalies are probably related to basic dykes associating with epidotic alterations which are situated between metasomatic and microdioritic units. Based on the results obtained from multi-fractal modeling, the locations of the main anomalies of La, Ce and Y were recognized which all are in the western, central, southern, and SE parts of the study area. Several high and moderate concentration anomalies obtained from the C–A model were confirmed by ground surveying and compared with the achieved result from remote sensing investigation. According to the correlation between geological particulars and obtained REEs anomalies, it has been proved that the proper and promising areas are in metasomatite rock units, chlorite and epidote alterations in the western and central part of the study area. By Scanning Electron Microscope (SEM) studies of davidite and uraninite minerals, it was determined that the REEs mineralization in this area have taken place mostly in the form of replacement in radioactive elements uranium (U) and thorium (Th). The combination of the field observations and mineralogical studies based on the type of REEs mineralization in the study area revealed that one of the main factors controlling the mineralization is related to metasomatism.18131833

Predictive mapping of prospectivity and quantitative estimation of undiscovered VMS deposits in Skellefte district (Sweden)

Mapping of mineral prospectivity and assessment of undiscovered mineral deposits both aim to delineate prospective ground for mineral exploration, but the latter is usually carried out exclusive of the former. We propose that the spatial distribution of known mineral deposits of the type sought is the key to link mapping of mineral prospectivity and assessment of undiscovered deposits. We demonstrate this proposition in regional-scale mapping of prospectivity for volcanogenic massive sulphides (VMS) deposits and estimation of undiscovered VMS endowment in the Skellefte district (Sweden). The results of analyses of the spatial distribution of known VMS deposits and their spatial associations with geological features are consistent with existing knowledge of geological controls on VMS mineralization in the district, and we used them to define spatial recognition criteria of regional-scale VMS prospectivity. Integration of layers of evidence representing spatial recognition criteria of VMS prospectivity via application of data-driven evidential belief functions results in a regional-scale map of prospective areas occupying 15% of the district and having fitting and prediction-rates of 100%. We used the map of prospective areas and proxy measures for degrees of exploration based on the spatial distribution of known VMS deposits in one-level prediction of undiscovered mineral endowment. We obtained estimates of 709 Kt undiscovered Cu endowment, 3190 Kt undiscovered Zn endowment, 95 Mt undiscovered ore tonnage, and 48 undiscovered VMS deposits. These estimates are slightly (ca. 5% on average) lower than, and thus corroborated by, estimates obtained via radial-density fractal analysis of the spatial distribution of known VMS deposits. Therefore, mineral prospectivity mapping can be a part of mineral resource assessment if the spatial distribution of discovered deposits of the type sought is considered in both predictive modeling processes