Geochemical Mapping Research Articles

Estimation and comparison of the environmental impacts of acid mine drainage‐bearing river water in the Bor and Majdanpek porphyry copper mining areas in Eastern Serbia

AbstractMining activities in the Bor and Majdanpek mining areas in Eastern Serbia started in 1903 and 1961, respectively. Environmental problems in the Bor mining area began after the opening of the Bor mine. Long‐term pollution of river water in the Bor and Majdanpek mining areas has an environmental impact on East Europe because all of the river water from these mining areas flows into the Danube River. However, the sizes of areas with pollution and the differences between the environmental impacts of the Bor and Majdanpek mining areas are not clear. In order to determine the effects of mining activities on river water in the study area, creation of geochemical maps showing the distributions of sulfate, heavy metals, and arsenic; estimation of threshold values to discriminate anomalous values from background values; and comparison of the environmental impacts of the two mining areas were carried out. High concentrations of SO42−, Fe, As, Cu, and Mn were found in the Bor River, Krivelj River, and Bela River located in the Bor mining area. These rivers are characterized by acidic pH ranging from 2.9 to 6.2. High concentrations of these components were also measured in the Small Pek River and the upper reach of the Pek River. These rivers are located in the Majdanpek mining area and are characterized by weakly alkaline pH (7.3–8.4). The acidic river water in the Bor mining area transports large quantities of heavy metals and arsenic downstream (6,900 t/year of Fe, 42 t/year of As, 910 t/year of Cu, and 187 t/year of Mn). On the other hand, the weakly alkaline river water in the Majdanpek mining area transports smaller quantities of heavy metals and arsenic downstream (160 t/year of Fe, 0.1 t/year of As, 6 t/year of Cu, and 272 t/year of Mn). The environmental impact of the Bor mining area is significantly larger than that of the Majdanpek mining area. In addition, on the basis of the distribution of anomalous values in river water, pollution caused by mining activities reaches the Danube River, which is located more than 100 km from the Bor and Majdanpek mining areas. Concentrations of SO42−, Fe, As, Cu, and Mn in the Bela River in the Bor mining area have been greatly decreased after mixing of acidic polluted water of the Bela River with water of the Timok River containing a high bicarbonate concentration. This fact suggests that river water in the Bor and Majdanpek mining areas has sufficient capacity for neutralization. Considering appropriate countermeasures of environmental reclamation, such as artificial neutralization at some important sources of waste water before discharging the waste water from the mining sites, there is a possibility for environmental reclamation in both mining areas because unpolluted river water in the study area has sufficient capacity for neutralization in a natural system.

Contamination, sources and environmental risk assessment of heavy metals in water, sediment and soil around an abandoned Pb mine site in North East Morocco

Metal Mining Contamination is a widespread problem in the world. However, the assessment of abandoned mine metal contamination, especially in Morocco, has not been studied sufficiently. In this study, a total of 83 samples of water, sediments, and soils were collected to investigate the concentrations of heavy metals (HMs) around an abandoned mining area, named: Zeida in North East Morocco. Furthermore, geochemical mapping of these elements has been also conducted. The contamination and environmental risk introduced by the accumulation of HMs has been assessed using numerous ecological indexes, such as: geo-accumulation (Igeo), Potential Ecological Risk Index and Modified Contamination Degree (MCd) to name just a few. Add to that the assessment of water quality using water quality assessment indexes. The results showed that all major elements and HMs of the river and its tributaries were within the Guidelines for Drinking-Water Quality (GDWQ), except for levels of HCO3−, and K+. The hydrochemical facies was dominated by calcium magnesium bicarbonate (CaMg–HCO3), and the concentrations changed in the range (µg/l): Zn: 14.78–152.00, Cr: 2.56–13.23, Cu: 0.96–12.35, Pb: 0.03–11.26, As: 0.98–3.24, Ni: 0.11–1.34 and Cd: 0.01–0.31, respectively. The spatial distribution of HM concentration and numerous ecological indexes in soil and sediment samples revealed that the highest values were located in and near the tailings, and declined downstream, which classified these sites as very highly contaminated and severely hazardous. Vertically, the soil concentration of HMs accumulated increasingly in relation to depth, and that in fact highlighted their potential mobility. HM concentrations (mg/kg) in sediments were in the range of: Pb: 43.79–9889.30, As: 104.57–289.00, Cr: 25.84–125.00, Zn: 40.78–121.75, Cu: 8.85–36.11, Ni: 1.99–21.00 and Cd: 0.10–0.46, respectively. While the average concentration in the three depths of soil (mg/kg) were in the range of: Pb: 27.00–11,400.00, Zn: 36.00–231.33, As: 42.33–172.00, Cr: 21.67–105.33, Cu: 18.33–143.33, Ni: 13.67–40.33 and Cd: 0.04–1.33, respectively. Multivariate statistical analysis indicated that HMs were related to the dispersion of tailings materials, with the exception of Ni and Cr which were related to lithological source.

Gold enrichment characteristics and exploration prospects in Zambia: Based on 1 ∶ 1000000 geochemical mapping

The 1∶1000000 geochemical mapping of Zambia provides catchment sediment geochemical data for 58 elements including Au from 746 sediment samples at 736 sampling sites, corresponding to a sampling density of about one site per 1000 km2. Under strict quality control using field duplicates, certified reference materials, and analytical replicate samples, the Au was determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The detection limit of Au was 0.20 × 10−9. The 95% range (2.5%–97.5%) of Au concentrations was from 0.24 × 10−9 to 1.36 × 10−9, and the median value was 0.40 × 10−9. The most noticeable Au distribution patterns shown on the map are mainly located between Lusaka and Ndola (Lufilian Arc Belt). In addition, several high Au value areas occurred in Mansa, Muyombe, Chipata, and Livingstone. The spatial distribution patterns of Au in tectonic units, drainage basins, and geomorphological landscapes could be related to the Lufilian Arc Belt and Bangweulu Block. The Au concentrations show metallogenic belts between Muyombe and Mbala areas, between Mansa and Ndola areas, and between Lusaka and Kasempa areas.© 2022 China Geology Editorial Office.

Watershed analysis for geochemical mapping in Japan based on a hydrologic model: The concentrations of 53 elements and the dominant lithology in a drainage basin

Watershed analysis for geochemical mapping in Japan based on a hydrologic model: The concentrations of 53 elements and the dominant lithology in a drainage basin

Alkali fusion co-precipitation/cation exchange/extraction enrichment for determination of trace rare earth elements in rocks by inductively coupled plasma mass spectrometry

In this paper, three separation and pre-enrichment methods of Mg(OH)2 and Fe(OH)3 co-precipitation, cation exchange and 1-phenyl-3-methyl-4-benzoyl-pyrazolone (PMBP) extraction were established by sodium peroxide alkali fusion digestion. Ca, Na and K, etc. were virtually eliminated from the analysis solutions using three sample processing procedures, thereby avoiding potential matrix interference and mass spectrometry interference due to high salt content. The detection limits of three methods were 0.0009-0.0076 mg/kg，0.0011-0.0062 mg/kg，0.0023-0.0114 mg/kg, respectively；the relative deviations of the determined rare earth elements (REEs) were -6.9-7.6%, -9.1-6.6% and -8.4-12.3%，respectively. The %RSD values of the three methods were lower than 10%, demonstrating good precision. The fit for purpose of the results was also evaluated by the quality criteria test proposed by the International Geological Correlation Programme (IGCP), from which it can be deduced that the three methods were adequate considering geochemical mapping application. The three sample processing procedures can be applied for the determination of rare earth elements in rocks.

Sampling density and spatial analysis: a methodological pXRF study of the geochemistry of a Viking-Age house in Ribe, Denmark

This study explores the significance of spatial sampling resolution on portable X-ray fluorescence (pXRF) analysis of an archaeological settlement site with favorable preservation conditions and clearly defined stratigraphic contexts as a benchmark study to interpret geochemical mapping of anthropogenic elemental markers. We present geochemical elemental mapping of a Viking-Age house floor in Denmark based on an unprecedented sampling density of a 0.25-m grid. In order to establish a fast, cost-efficient, comparable approach of how different sizes of data resolution affect the spatial elemental patterns, the data is analysed using three different grid sizes: 0.25 m × 0.25 m, 0.5 m × 0.5 m, and 1.0 m × 1.0 m. We analysed each grid size with selected anthropogenic markers (CaO, Cu, P2O5, and Sr) using ordinary kriging. The CaO, P2O5, and Sr patterns display a strong inter-correlation between data points up to a distance of 1–1.5 m from one another. At the highest resolution (0.25-m grid), all of the elements display a high degree of detail in the variation of the elements across the indoor surface with low standard deviations. Hence, the precise position of hot and coldspots, and spread of bounded concentration zones, is easily recognized in the maps. With the low resolution (1.0-m grid), the borders between high and low concentrations become more blurred and the indications of smaller hotspots (possible activity areas) are completely lost. Especially, Cu displays a high degree of clustering, which the high-resolution sampling could best reveal. This benchmark study shows that it is realistic to perform large-scale geochemical surveys of archaeological settlements using pXRF spectrometry in a standard archaeological excavation context, but also that sampling distances of 0.5 m × 0.5 m or finer are best suited to in indoor contexts.

Application of spatial distribution patterns of multi-elements in geochemical maps for provenance and transfer process of marine sediments in Kyushu, western Japan

Abstract We investigated the origin of marine sediments and their transfer by water currents using the spatial distribution patterns of multi-elements in terrestrial and marine areas of Kyushu, western Japan. Quaternary volcanic material covers Cretaceous granitic rock and Jurassic–Paleogene sedimentary rock of an accretionary complex in this region. Cluster analysis based on chemical compositions identified the origin of marine sediments from stream sediments originating from the above lithologies. Pyroclastic-flow deposits associated with caldera formation, particularly that of the Kikai Caldera (7.3 ka), were characterized by low Cr/Ti and La/Yb ratios. In contrast, the La/Yb ratio was very high in sediments derived from granitic rock and sedimentary rock of the accretionary complex. The spatial distributions of low Cr/Ti and La/Yb ratios suggest that marine sediments containing pyroclastic materials, which are found within an 80 km radius of the Kikai Caldera, were distributed on the shelf and transported northeastwards by a branch of the Kuroshio Current. The continuous distribution of the medium Cr/Ti and high La/Yb ratios from the land to the coast, slope and deep basin on the Pacific Ocean side suggests that sediments supplied from the terrestrial area were transferred by gravitational transport from the shelf to the deep basin.

Interpretations of Hg anomalous sources in drainage sediments and soils in China

China Geochemical Baselines project provides mercury dataset of drainage catchment sediments and soils during 2008–2012 in China. Fifty-seven mercury anomalous regions exceeding the risk limits of the China National Environmental Standards for Heavy Metals in Soil (GB 15618-1995) are delineated in China. The sources of Hg risk anomalies of the top and deep samples are variously interpreted with respect to geology/mineralisation and human activities. Nearly 72% anomalies (41 among the totaling 57 anomalous locations) are due to natural geological mineralisation belts and mining of Hg, As, Sb, Au, Ag, Pb, Zn, coal etc. The mining activities cause superimposed contents of Hg on the natural mineralisation belts. The influence of large-scale mining of Hg, non-ferrous metals and gold are significantly reflected in the geochemical maps. The anthropogenic sources of urbanisation emission, agriculture, coal combustion, and smelting industry cause the much more degree of mercury pollution in the eastern China where is highly populated and industrial density areas. Agriculture is an important Hg-emission source in the eastern China and Chengdu Plains where agricultural base for more than 2500 years in China. It is critical to carry out the follow-up detailed source investigation and monitor the temporal changes of Mercury in soils.

Weighting of BLEG data with drainage and catchment properties to enhance Au anomalies

This research aims to take the effect of drainage sediment dilution into consideration by using catchment weighted-bulk leachable extractable gold (CW-BLEG) data in order to enhance and recognize Au anomalies. As a case study, an area in the Eskisehir region in Western Turkey was selected. In this area, gold-bearing crystalline quartz veins, of probable orogenic type, containing up to 20 g/t Au, occur in low-grade schists and marbles of the Karakaya Complex in the vicinity of the Sogut area. To classify the final geochemical maps of the BLEG data to differentiate Au anomalies from background, the singularity model was applied. After that, in order to take the sediments dilution effect (DE) into account, the other important factors in the study area such as the sinuosity index (SI) of the stream sediments per catchment, and the topography slope and area of each catchment were taken into consideration and implemented on the BLEG data. To do so, the CW-BLEG models based on the relation between the Au concentrations and each factor (i.e., C × sinuosity as DE-sinuosity, C × slope as DE-slope, and C × area as DE-area) were generated. Because of the insufficient number of known mineral deposits within the study area to evaluate the effectiveness of the models statistically, the models generated were compared with each other and studied using cross-validation. It demonstrated that the DE-area and DE-sinuosity models work better than the other model in recognizing strong and very strong anomalies considering the known mineral deposits. The cross-validation results show that the DE-area model provides a more robust result compared the other models. Considering the models generated, the very strong and strong Au anomalies in the western part of the study area are corresponded to the known gold mineralization (e.g., Sogut and Mayislar) hosted by the Karakaya Complex, and the anomalies in the eastern and central parts of the study area are associated with the Damdaca mineralization.

GEMAS: Geochemical distribution of Mg in agricultural soil of Europe

Agricultural soil (Ap-horizon, 0–20 cm) samples were collected from 33 European countries as part of the GEMAS (GEochemical Mapping of Agricultural and grazing land Soil) soil-mapping project. The Mg data derived from total concentrations (XRF) and two acid digestion methods, aqua regia (AR) and Mobile Metal Ion (MMI®), were used to provide an overview of its spatial distribution in soil at the continental-scale. Magnesium is one of the most abundant elements in the Earth's crust and essential nutrient for plants and animals and its presence in soil is, therefore, important for soil quality evaluation.In this study, the geochemical behaviour of Mg in European agricultural soil was investigated in relation to a variety of soil parent materials, climatic zones, and landscapes. The chemical composition of soil reflects mostly the primary mineralogy of the source bedrock, and the superimposed effects of pre- and post-depositional chemical weathering, controlled by element mobility and formation of secondary phases such as clays.Low Mg concentrations in agricultural soil occur in regions with quartz-rich glacial sediments (Poland, Baltic States, N. Germany), and in soil developed on quartz-rich sandstone parent materials (e.g., central Sweden). High Mg concentrations occur in soil developed over mafic lithologies such as ophiolite belts and in carbonate-rich regions, including karst areas. The maximum extent of the last glaciation is well defined by a Mg concentration break, which is marked by low Mg concentrations in Fennoscandia and north-central Europe, and high Mg concentrations in Mediterranean region. Lithology of parent materials seems to play a key role in the Mg nutritional status of agricultural soil at the European scale. Influence from agricultural practice and use of fertilisers appears to be subordinate.Comparison of the continental-scale spatial distribution of Mg in agricultural soil by using the results from three analytical methods (XRF, AR and MMI®) provides complementary information about Mg mobility and its residence time in soil. Thus, allowing evaluation of soil weathering grade and impact of land use exploitation.

Yerevan soil radioactivity: Radiological and geochemical assessment

Spatial pattern of naturally occurring radionuclides (NOR): 226Ra, 232Th, 40K, and artificial 137Cs was studied using soil samples of the multipurpose geochemical survey of the city of Yerevan, capital of Armenia. High purity Ge detector-based gamma spectrometry system was used for the determination of radionuclides activity concentrations in urban soils. A combination of compositional data analysis, geochemical mapping and radiological assessment were applied to reveal potential factors of technologically enhanced natural radioactivity and excess lifetime cancer risk for Yerevan’s population due to NOR and artificial 137Cs in the urban environment. Statistical methods with the geochemical mapping revealed the great contribution of soil-forming rocks to NOR distribution in urban soils. The spatial distribution of calculated radiological indices and dose rates levels follows the distribution patterns of NOR. The activity concentration of fallout radionuclide 137Cs was within the range typical for the studied altitudes. Above baseline activity of 137Cs was observed in the north-western and western part of the city that is in typical ranges of 137Cs content in soil derived from global radioactive fallout. Urban soils of Yerevan were found radiologically safe, however, igneous rock derived soils are a sink of NOR and the main environmental source of continuous exposure to the residents. Values of excess lifetime cancer risk were higher than mean global value.

Late Paleozoic Element Migration and Accumulation under Intracontinental Sinistral Strike‐slip Faulting in the West Junggar Orogenic Belt, NW China

AbstractThe migration, accumulation and dispersion of elements caused by tectonic dynamics have always been a focus of attention, and become the basis of tectono‐geochemistry. However, the effects of faulting, especially strike‐slip faulting, on the adjustment of geochemical element distribution, are still not clear. In this paper, we select the West Junggar Orogenic Belt (WJOB), NW China, as a case study to test the migration behavior of elements under tectonic dynamics. The WJOB is dominated by NE‐trending large‐scale sinistral strike‐slip faults such as the Darabut Fault, the Mayile Fault, and the Baerluke Fault, which formed during the intracontinental adjustment under N–S compression during ocean‐continental conversion in the Late Paleozoic. Geochemical maps of 13 elements, Al, W, Sn, Mo, Cu, Pb, Zn, As, Sb, Hg, Fe, Ni, and Au, are analyzed for the effects of faulting and folding on element distribution at the regional scale. The results show that the element distribution in the WJOB is controlled mainly by two mechanisms during tectonic deformation: first is the material transporting mechanism, where the movement of geological units is consistent with the direction of tectonic movement; second is the diffusion mechanism, especially by tectonic pressure dissolution driven by tectonic dynamics, where the migration of elements is approximately perpendicular or opposite to the direction of tectonic movement. We conclude that the adjustment of element distributions has been determined by the combined actions of transporting and diffusion mechanisms, and that the diffusion mechanism plays an important role in the formation of geochemical Au blocks in the WJOB.

Stream Sediments Geochemical Exploration in Wadi El Reddah area, Northeastern Desert, Egypt

<p>Wadi El Reddah representing a semi-closed basin, extends in the N-S direction. It has only one outlet at the northern tip while the wadi collects floodwater from internal tributaries along wall rocks. The present study discusses the relationship between geology and geochemistry data to detect anomalous radioactive locations. The geochemical maps show the mineralization areas with abnormal rare metal contents. This led to two uranium occurrences (GXXIII and GXXIV) at Gabal Gattar in the perthitic leucogranite. At Wadi El Reddah, high contents of pathfinder elements (REE, Y, Zn, Nb and As) were discovered at the southern and eastern boundaries. This may be attributed to the presence of alkali feldspar granite at Gabal Gattar at the upstream of Wadi El Reddah and also to the sharp contact between Gabal Gattar and Hammamat Sedimentary rocks. A strong positive correlation coefficient between Fe<sub>2</sub>O<sup>t</sup> and or Al<sub>2</sub>O<sub>3</sub> with Zr, Hf, Nb, Ta, REE, U, Rb, and Th reflects their association with thematization processes.</p>

Regional Geochemical Map of West Java, Indonesia: Evaluation for Environmental and Mineral Resources

A The regional geochemical mapping project was conducted by the Centre for Geological Survey, Geological Agency, Ministry of Energy and Mineral Resources during 2011 to 2012 in Banten and West Java Provinces areas. Geological and topographic maps with scale of 1:100.000 as the base maps were used. Stream sediment samples were collected in this geochemical mapping project with the fraction size are 80# and the density of samples represent one sample for about 25 km2. The project already successfully collected 1215 stream sediment samples covering twenty one base maps. The samples collecting were the result of collaboration between Geological Agency and universities. Moreover, the geochemical analysis was conducted with the XRF (X-Ray Fluorescence) method at the Geological Laboratory of Centre for Geological Survey. This method could analyze for 30 elements and show significant anomalies with presuming result from natural product or derived from human or urban activities. The volcanic products from quaternary volcanoes are clearly identified on distribution of As, Ba, Cl, Cu and Zr elements. Epithermal mineralization zone has an anomaly of distribution of Cu, Fe, Pb, and Zn. Meanwhile the human activities are showing from geochemical map of Cl, Cr, Cu, Hg, Pb and Zn that show scattered anomalies localized close to the cities, industries and mining area.

Biogeochemical response of Pinus brutia and Olea europaea to lithological variations and Cu mineralisation in Cyprus

Regional geochemical mapping programs are predominantly based on regolith materials as the sampling media. The use of plant organs has been more limited, despite potential advantages demonstrated in more localised studies that have examined biogeochemical responses to various types of mineralisation or contamination, or sought to identify species with phytoremediation potential. This study investigated the effects of variations in lithology and mining wastes on the multielement chemistry of Pinus brutia (pine) needles and O. europaea (olive) leaves, obtained from low-density traverses across Cyprus and detailed sampling around two Cyprus-style VHMS Cu-deposits. A total of 476 samples were analysed by a combination of inductively-coupled plasma mass spectrometry (ICP-MS) and portable X-ray fluorescence spectrometry (pXRF). At the regional scale there are substantial differences in the composition of the pine needles, especially for Ni, Ba, Sr, Mn and Zn, between the major lithological groups that range from the ultramafic and mafic units of the Troodos Ophiolite to the mineralised pillow basalts and various marine carbonate units. Both pine needles and olive leaves display intense Re anomalies in areas with mine wastes and consistently low concentrations in background areas. The response for Cu and other macro- or micronutrient elements to contamination is less pronounced and may reflect barriers to uptake by the plants. The relative magnitude of variations between the different lithologies in median plant metal concentrations is equivalent to that displayed in soils of the Geochemical Atlas of Cyprus (e.g. REE, Zn and Sr), but for some elements the patterns differ substantially. There is close correlation between the ICP-MS and pXRF data for elements where most values are above pXRF detection limits. The study further demonstrates the potential of plants in regional geochemical mapping for a range of applications, in combination with or as an alternative to conventional regolith media.

Urban street dust in the Middle East oldest oil refinery zone: Oxidative potential, source apportionment، and health risk assessment of potentially toxic elements

The current study is the intented to investigate the intensity of pollution, source characterization, oxidative potential, and human health risks of fourteen potentially toxic elements in the street dust of the Middle East oldest oil refinery zone. Thirty five street dust samples were collected from various regions in Abadan and Khorramshahr cities. The mean concentration of As, Mo, Cu, Pb, Hg, Zn, Cd, and Sb in Abadan street dust were 5.55, 3.39, 83.68, 49.82, 4493.54, 281.24, 1.15,and 1.17, while in Khorramshahr As, Mo, Cu, Pb, Hg, Zn, Cd, and Sb were.14, 2.58, 74.35, 56.50, 0.74, 214.26, 0.62, and 1.18, respectively. The concentration of these elements in both cities is higher than the local background values. Potential ecological risk index and pollution load index at all stations of both cities are greater than 1, indicating a high pollution load in the study area. Calculated enrichment factor showed high enrichment of Hg, Sb, Cd, Mo, Cu, Pb, and Zn in both areas. Of particular concern is the enrichment factor for mercury which proved to be 3370.54 ppb in the vicinity of the petrochemical unit in Abadan city (EF > 40). The results of positive matrix factorization receptor model together with geochemical maps and multivariate statistics indicated that industrial activities (especially petrochemical industries) are responsible for Hg, Cu, and Zn pollution, while exhaust emissions are responsible for Mo, Pb, Cd, and Sb, and natural sources for Al, Cr, Mn, Fe, Co, and Ni. The percentage of OPAA in the region ranged from 15.1 to 26.4 and OPGSH ranged from 9.5 to 24.4. The percentage of OPTOTAL/μg (OPAA/μg + OPGSH/μg) values varied between 0.6 and 1. The health risk evaluation models indicated that specific attention should be paid to Hg, Cd, Pb, and Zn and that the higher oxidative potential of street dust recovered from polluted locations is also a matter of concern in Abadan and Khorramshahr Cities.

Controls on soil geochemistry fractal characteristics in Lemesos (Limassol), Cyprus

This study extends the program of urban soil geochemical mapping in Cyprus to Lemesos, the country's second largest and fastest developing urban centre. Data from 411 soil samples are combined with samples previously analysed as part of the detailed soil geochemical atlas of Cyprus (GAC). Parent lithology is the dominant control on the distribution of most elements with soils derived from carbonate units contrasting with those developed on alluvium-colluvium that contains input from both the carbonates and mafic-ultramafic units of the nearby Troodos Ophiolite. Anthropogenic contamination is best indicated by the Pb-Sn-Ag-Bi suite with elevated values in a belt crossing the southern and older section of the city that is unrelated to parent lithology or current land use classification. As in Lefkosia, children's playgrounds display much higher As contents than at other sites due to application of a natural secondary carbonate (‘pouri’) as the surface layer, and elevated concentrations of Cu, Fe, Ti, Al, S and Mn associated with basaltic soils used in most school grounds. Multivariate patterns in the Lemesos data largely reflect those of similar parent lithologies within the national soil atlas, but there is closer clustering of the contamination-related elements and an ultramafic suite involving Ni-Cr-Pt-Pd-V-Co in Lemesos. Whereas most elements display multifractal populations using number-size fractal modelling, in urban and contaminated areas some higher concentration element populations do not display fractal behaviour, thus providing a means of identifying anthropogenic influences.

Unsupervised geochemical classification and automatic 3D mapping of the Bolshetroitskoe high-grade iron ore deposit (Belgorod Region, Russia)

We stated and solved three successive problems concerning automatization of geological mapping using the case of the Bolshetroitskoe high-grade iron ore deposit in weathered crust of Banded Iron Formation (Kursk Magnetic Anomaly, Belgorod Region, Russia). (1) Selecting a classification (clustering) method of geochemical data without reference sampling, i.e., solution of an “unsupervised clustering task”. We developed 5 rock classifications based on different principles, i.e., classification by visual description, by distribution of economic component (Fe2O3), by cluster analysis of raw data and centered log-ratio transformation of the raw data, and by artificial neural network (Kohonnen’s self-organized map). (2) Non-parametric comparison of quality of the classifications and revealing the best one. (3) Automatic 3D geological mapping in accordance with the best classification. The developed approach of automatic 3D geological mapping seems to be rather simple and plausible.

Classical and Robust Regression Analysis with Compositional Data

Compositional data carry their relevant information in the relationships (logratios) between the compositional parts. It is shown how this source of information can be used in regression modeling, where the composition could either form the response, or the explanatory part, or even both. An essential step to set up a regression model is the way how the composition(s) enter the model. Here, balance coordinates will be constructed that support an interpretation of the regression coefficients and allow for testing hypotheses of subcompositional independence. Both classical least-squares regression and robust MM regression are treated, and they are compared within different regression models at a real data set from a geochemical mapping project.

Geochemical mapping in a subtropical estuarine system influenced by large grain-shipping terminals: Insights using Metal/Metal ratios and multivariate analysis

In this study, we combine the use of Metal/Metal ratios of 134 sediment samples with multivariate analysis to provide the first geochemical mapping of a large subtropical estuary influenced by one of the largest grain-shipping terminals of South America. Together with grain-size data, the results allowed us to efficiently map the different sectors of the estuarine complex, defining its geochemical faciology. Also, potassium-related ratios appeared to be reliable proxies for the identification of point sources of terrigenous sediments. Since there was no evidence of widespread trace metal contamination, the results here presented can be used as a baseline for the area.