Y. Vodyanitskii, T. Minkina, I. Zamulina, T. Bauer, I. Zinicovscaia
The influence of alkalinity and other factors on the content of microelements in soils developed on marine deposits is studied. Traditional indicators of exchangeable sodium percentage do not demonstrate the ability to retain microelements, but one can see a close direct correlation between the content of macroelements and the retention of microelements. The efficiency of this group is increased if we take into account the concentration of total Na. The element compositions of soil were determined by neutron activation method. The results show that the Na-related alkalinity of soil can enhance the role of main macroelements and increase the dispersibility of particles and their aggregating capacity relative to microelements. The microelement composition was also distinguished by the Zn concentration in Gleyic Solonchaks due to the anionogenic composition of gley.
{"title":"Role of total Na in the retention of microelements in soils on marine deposits","authors":"Y. Vodyanitskii, T. Minkina, I. Zamulina, T. Bauer, I. Zinicovscaia","doi":"10.1144/geochem2021-069","DOIUrl":"https://doi.org/10.1144/geochem2021-069","url":null,"abstract":"The influence of alkalinity and other factors on the content of microelements in soils developed on marine deposits is studied. Traditional indicators of exchangeable sodium percentage do not demonstrate the ability to retain microelements, but one can see a close direct correlation between the content of macroelements and the retention of microelements. The efficiency of this group is increased if we take into account the concentration of total Na. The element compositions of soil were determined by neutron activation method. The results show that the Na-related alkalinity of soil can enhance the role of main macroelements and increase the dispersibility of particles and their aggregating capacity relative to microelements. The microelement composition was also distinguished by the Zn concentration in Gleyic Solonchaks due to the anionogenic composition of gley.","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45962171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Powell, J. Percival, E. Potter, R. van der Lelij, R. Xie
The Patterson Lake corridor (PLC) along the southwestern margin of the Athabasca Basin contains high-grade uranium deposits entirely within crystalline basement rocks. Visible-near infrared - shortwave infrared (VNIR-SWIR) spectroscopy measurements were collected on drill core samples from several locations in the PLC. The Triple R and Arrow deposits exhibit downhole spectral trends related to the crystallinity and thermal maturity of clays (illite and kaolinite) and mineralization. The K-Ar dates of silt-and-clay size fractions (10–6 µm; 6–2 µm; 2–0.6 µm; 0.6–0.2 µm; <0.2 µm) from five clay-altered samples decrease with grain size, and span 1608 ± 17 Ma to 1060 ± 14 Ma for the Spitfire discovery (n = 14) and 1342 ± 17 Ma to 289 ± 4.3 Ma for the Arrow deposit (n = 4). Alteration assemblages are broadly similar to Athabasca Basin basement-hosted deposits, and K-Ar dates indicate that high-grade uranium mineralization in the PLC reflects remobilization and concentration of primary ores. Integration of geochronology, clay mineralogy and VNIR-SWIR spectral parameters identify fertile fluid conduits when expanded to property- or corridor-scales, and provide additional evidence that ore grades of the Athabasca Basin deposits reflect several stages of hydrothermal mineralization spanning ∼1000 Ma.Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathwaysSupplementary material:https://doi.org/10.6084/m9.figshare.c.6033890
{"title":"Mineralogy and K-Ar geochronology of clay alteration associated with uranium mineralization in the Patterson Lake Corridor, Saskatchewan","authors":"J. Powell, J. Percival, E. Potter, R. van der Lelij, R. Xie","doi":"10.1144/geochem2021-061","DOIUrl":"https://doi.org/10.1144/geochem2021-061","url":null,"abstract":"The Patterson Lake corridor (PLC) along the southwestern margin of the Athabasca Basin contains high-grade uranium deposits entirely within crystalline basement rocks. Visible-near infrared - shortwave infrared (VNIR-SWIR) spectroscopy measurements were collected on drill core samples from several locations in the PLC. The Triple R and Arrow deposits exhibit downhole spectral trends related to the crystallinity and thermal maturity of clays (illite and kaolinite) and mineralization. The K-Ar dates of silt-and-clay size fractions (10–6 µm; 6–2 µm; 2–0.6 µm; 0.6–0.2 µm; <0.2 µm) from five clay-altered samples decrease with grain size, and span 1608 ± 17 Ma to 1060 ± 14 Ma for the Spitfire discovery (n = 14) and 1342 ± 17 Ma to 289 ± 4.3 Ma for the Arrow deposit (n = 4). Alteration assemblages are broadly similar to Athabasca Basin basement-hosted deposits, and K-Ar dates indicate that high-grade uranium mineralization in the PLC reflects remobilization and concentration of primary ores. Integration of geochronology, clay mineralogy and VNIR-SWIR spectral parameters identify fertile fluid conduits when expanded to property- or corridor-scales, and provide additional evidence that ore grades of the Athabasca Basin deposits reflect several stages of hydrothermal mineralization spanning ∼1000 Ma.Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathwaysSupplementary material:https://doi.org/10.6084/m9.figshare.c.6033890","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47353615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Mount, E. Potter, Z. Yang, M. Fayek, J. Powell, G. Chi, H. Rizo
The Patterson Lake corridor (PLC), located on the southwestern margin of the Athabasca Basin, contains several basement-hosted uranium deposits that formed via protracted, structurally controlled fluid-rock interactions. Using multiple generations of pyrite grains (pre-, syn- and post-mineralization) from the Triple R deposit, in-situ iron isotopic analyses revealed large intra-sample and -grain variations (δ56Fe values ranging from -2.21 to +1.67 ‰) whereas sulfur isotopes yielded minor variations (δ34S values ranging from -4.44 to + 5.3 ‰) relative to natural isotopic variations for both elements. The wide range in δ56Fe values supports textural and chemical evidence that fluctuating oxidation states and chemistry in the fault zone fluids caused multiple generations of pyrite oxidation and precipitation. Sulfur isotope data from shallower mineralized zones show a slight enrichment in heavier isotopes consistent with limited Rayleigh fractionation. However, when coupled with iron isotope data, the overall dataset supports a sulfur-rich, open system wherein heat from intrusions at depth and fault movements drove sulfur-rich fluids upwards, causing precipitation of pre-mineralization pyrite and graphite. During fault reactivation, fluid pressure fluctuations between hydrostatic and sub-hydrostatic regimes drew oxidizing, uranium-bearing, basinal brines down into the basement to react with sulfides in the host rocks and deeply sourced, H2S-bearing reducing fluids. These redox reactions and fluid mixing resulted in precipitation of uraninite and syn-mineralization pyrite. These results further support the importance of structural control, repeated faulting and thermal anomalies in the basement for mineralization, necessitating re-examination of the current exploration model for unconformity-related uranium deposits.Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathwaysSupplementary material:https://doi.org/10.6084/m9.figshare.c.6026621
{"title":"Formation of the high-grade Triple R uranium deposit revealed by Fe and S isotopes in pyrite","authors":"S. Mount, E. Potter, Z. Yang, M. Fayek, J. Powell, G. Chi, H. Rizo","doi":"10.1144/geochem2021-023","DOIUrl":"https://doi.org/10.1144/geochem2021-023","url":null,"abstract":"The Patterson Lake corridor (PLC), located on the southwestern margin of the Athabasca Basin, contains several basement-hosted uranium deposits that formed via protracted, structurally controlled fluid-rock interactions. Using multiple generations of pyrite grains (pre-, syn- and post-mineralization) from the Triple R deposit, in-situ iron isotopic analyses revealed large intra-sample and -grain variations (δ56Fe values ranging from -2.21 to +1.67 ‰) whereas sulfur isotopes yielded minor variations (δ34S values ranging from -4.44 to + 5.3 ‰) relative to natural isotopic variations for both elements. The wide range in δ56Fe values supports textural and chemical evidence that fluctuating oxidation states and chemistry in the fault zone fluids caused multiple generations of pyrite oxidation and precipitation. Sulfur isotope data from shallower mineralized zones show a slight enrichment in heavier isotopes consistent with limited Rayleigh fractionation. However, when coupled with iron isotope data, the overall dataset supports a sulfur-rich, open system wherein heat from intrusions at depth and fault movements drove sulfur-rich fluids upwards, causing precipitation of pre-mineralization pyrite and graphite. During fault reactivation, fluid pressure fluctuations between hydrostatic and sub-hydrostatic regimes drew oxidizing, uranium-bearing, basinal brines down into the basement to react with sulfides in the host rocks and deeply sourced, H2S-bearing reducing fluids. These redox reactions and fluid mixing resulted in precipitation of uraninite and syn-mineralization pyrite. These results further support the importance of structural control, repeated faulting and thermal anomalies in the basement for mineralization, necessitating re-examination of the current exploration model for unconformity-related uranium deposits.Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathwaysSupplementary material:https://doi.org/10.6084/m9.figshare.c.6026621","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43742525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hongli Li, Zenghua Li, Y. Ouyang, Lifei Yang, Youguo Deng, Qibao Jiang, Teng Deng, Pei Shang, Yuheng Lin, Haoxuan Zeng
The Jiujiang region in the northeastern Jiangxi Province is known for hosting many black shale-type vanadium deposits, which are mainly hosted in the Cambrian Hetang Formation and Sinian Piyuancun Formation. In this paper, based on stream sediment data, principal component analysis (PCA) and spectrum–area (S–A) fractal modeling are used to identify geochemical anomalies associated with V mineralization. Firstly, a dataset containing 957 samples of stream sediments with 39 elements was processed using correlation analysis and cluster analysis to find out the closest V-related elements, and Ag and Cd were obtained. Secondly, the raster maps of V, Ag and Cd were created using multifractal inverse distance weighted (MIDW) interpolation method. PCA was then employed to combine the concentration values of V, Ag and Cd into one single variable representing the internal relationships among the three elements. Finally, S–A analysis was used to decompose the first component pattern obtained through PCA and to extract anomalies from the complex background. The results show that the known V deposits are located within the highly anomalous areas, which are corelated well with the distribution of black shales of the Hetang and Piyuancun formations. It is suggested that the northeastern part of Jiangxi Province potentially hosts undiscovered V deposits, and the identified anomalies could be further used to guide mineral exploration.Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis
{"title":"Application of principal component analysis and spectrum-area fractal model to identify geochemical anomalies associated with vanadium mineralization in northeastern Jiangxi Province, South China","authors":"Hongli Li, Zenghua Li, Y. Ouyang, Lifei Yang, Youguo Deng, Qibao Jiang, Teng Deng, Pei Shang, Yuheng Lin, Haoxuan Zeng","doi":"10.1144/geochem2021-090","DOIUrl":"https://doi.org/10.1144/geochem2021-090","url":null,"abstract":"The Jiujiang region in the northeastern Jiangxi Province is known for hosting many black shale-type vanadium deposits, which are mainly hosted in the Cambrian Hetang Formation and Sinian Piyuancun Formation. In this paper, based on stream sediment data, principal component analysis (PCA) and spectrum–area (S–A) fractal modeling are used to identify geochemical anomalies associated with V mineralization. Firstly, a dataset containing 957 samples of stream sediments with 39 elements was processed using correlation analysis and cluster analysis to find out the closest V-related elements, and Ag and Cd were obtained. Secondly, the raster maps of V, Ag and Cd were created using multifractal inverse distance weighted (MIDW) interpolation method. PCA was then employed to combine the concentration values of V, Ag and Cd into one single variable representing the internal relationships among the three elements. Finally, S–A analysis was used to decompose the first component pattern obtained through PCA and to extract anomalies from the complex background. The results show that the known V deposits are located within the highly anomalous areas, which are corelated well with the distribution of black shales of the Hetang and Piyuancun formations. It is suggested that the northeastern part of Jiangxi Province potentially hosts undiscovered V deposits, and the identified anomalies could be further used to guide mineral exploration.Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49190377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Junliang Yang, Zhaoxian Yuan, E. Grunsky, Q. Cheng, Shubin Zhou
Transported soils cause difficulties in the identification of geochemical anomalies. It has been demonstrated that the joint application of Local Singularity Analysis (LSA) and Principal Component Analysis (PCA) can identify geochemical anomalies effectively, especially in regolith-covered areas. However, more convincing evidence is needed to explain the reasons for this. In this study, a soil profile overlying several mineralized veins cutting through the bedrock was analyzed in-situ using a portable X-ray fluorescence spectrometer. The patterns of two mineralization-related elements, Cu and Mo, were analyzed. The results revealed that the element concentrations of the soil sharply decreased as the distance from the bedrock increased, and this relationship can be described by a power law model. The LSA enhanced several vein-like anomalies corresponding to the mineralization veins in the bedrock, and the presence of vertically elongated weak anomalies in the soil indicates the migration of ore elements originating from the underlying bedrock through the soil. The statistics show that the patterns of the Local Singularity Index (LSI) are stable at different depths and in different media, whereas the concentration patterns are not. In addition, the mineralization-related elements have a higher correlation coefficient for the LSI than for the concentration. Since a previous simulation study determined that a mineralization indicative first principal component prefers that the variables have a close relationship and that the variables have similar patterns in different geological objects, the patterns discovered in this study explain why LSA is effective in identifying geochemical anomalies, especially when combined with PCA.Supplementary material: the high-resolution photo, the element concentration data and the lithologic data of the profile are available at https://doi.org/10.6084/m9.figshare.c.5957122.Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis
{"title":"Analysis of geochemical patterns in a soil profile over mineralized bedrock","authors":"Junliang Yang, Zhaoxian Yuan, E. Grunsky, Q. Cheng, Shubin Zhou","doi":"10.1144/geochem2021-088","DOIUrl":"https://doi.org/10.1144/geochem2021-088","url":null,"abstract":"Transported soils cause difficulties in the identification of geochemical anomalies. It has been demonstrated that the joint application of Local Singularity Analysis (LSA) and Principal Component Analysis (PCA) can identify geochemical anomalies effectively, especially in regolith-covered areas. However, more convincing evidence is needed to explain the reasons for this. In this study, a soil profile overlying several mineralized veins cutting through the bedrock was analyzed in-situ using a portable X-ray fluorescence spectrometer. The patterns of two mineralization-related elements, Cu and Mo, were analyzed. The results revealed that the element concentrations of the soil sharply decreased as the distance from the bedrock increased, and this relationship can be described by a power law model. The LSA enhanced several vein-like anomalies corresponding to the mineralization veins in the bedrock, and the presence of vertically elongated weak anomalies in the soil indicates the migration of ore elements originating from the underlying bedrock through the soil. The statistics show that the patterns of the Local Singularity Index (LSI) are stable at different depths and in different media, whereas the concentration patterns are not. In addition, the mineralization-related elements have a higher correlation coefficient for the LSI than for the concentration. Since a previous simulation study determined that a mineralization indicative first principal component prefers that the variables have a close relationship and that the variables have similar patterns in different geological objects, the patterns discovered in this study explain why LSA is effective in identifying geochemical anomalies, especially when combined with PCA.Supplementary material: the high-resolution photo, the element concentration data and the lithologic data of the profile are available at https://doi.org/10.6084/m9.figshare.c.5957122.Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44896929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yan Zhang, Li Zhang, Jie Zhou, Jitian Zhu, Lishan Tang, Yongzhang Zhou
In recent years, a high-quality reservoir was discovered in the Songnan Low Uplift in the eastern deepwater area of the Qiongdongnan Basin, northern South China Sea. To clarify that this area has good exploration prospects, this paper uses the multifractal moment method to analyze 2689 data points acquired from the basin in the southeast of the southern low bulge. It is pointed out that the fractal behaviors of different types of geochemical indices are often distinguished by multifractal spectra of different shapes, therefore, multifractal spectrum function analysis is used in this paper. These data were considered within the context of 13 oil and gas indices describing the multifractal spectrum function morphological characteristics. The results show that these indices can be divided into three types according to the multifractal spectrum. Indices with a strong multifractal spectrum function in the Songnan Low Uplift have the characteristics of a wide and continuous multifractal spectrum function, forming a right-skewed arc shape, while the other indices show weak or single fractal characteristics. The results are in good agreement with principle component analysis results, where the spectral function of each principal component shows that the gas source of the C1, C2, C3, nC4, nC5, and heavy hydrocarbons indices in the Songnan Low Bulge has multifractal characteristics. The weight of these indices with strong multifractal characteristics shows that the principle components C1, C2, and C3, and heavy hydrocarbons are important indices for delineating hydrocarbon prospects in the Songnan Low Uplift. Multifractal and spatial analysis techniques provide new ideas for index selection and comprehensive information extraction for oil and gas exploration.Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis
{"title":"Multifractal properties of oil and gas indices in Songnan Low Uplift of Qiongdongnan Basin deepwater area","authors":"Yan Zhang, Li Zhang, Jie Zhou, Jitian Zhu, Lishan Tang, Yongzhang Zhou","doi":"10.1144/geochem2021-092","DOIUrl":"https://doi.org/10.1144/geochem2021-092","url":null,"abstract":"In recent years, a high-quality reservoir was discovered in the Songnan Low Uplift in the eastern deepwater area of the Qiongdongnan Basin, northern South China Sea. To clarify that this area has good exploration prospects, this paper uses the multifractal moment method to analyze 2689 data points acquired from the basin in the southeast of the southern low bulge. It is pointed out that the fractal behaviors of different types of geochemical indices are often distinguished by multifractal spectra of different shapes, therefore, multifractal spectrum function analysis is used in this paper. These data were considered within the context of 13 oil and gas indices describing the multifractal spectrum function morphological characteristics. The results show that these indices can be divided into three types according to the multifractal spectrum. Indices with a strong multifractal spectrum function in the Songnan Low Uplift have the characteristics of a wide and continuous multifractal spectrum function, forming a right-skewed arc shape, while the other indices show weak or single fractal characteristics. The results are in good agreement with principle component analysis results, where the spectral function of each principal component shows that the gas source of the C1, C2, C3, nC4, nC5, and heavy hydrocarbons indices in the Songnan Low Bulge has multifractal characteristics. The weight of these indices with strong multifractal characteristics shows that the principle components C1, C2, and C3, and heavy hydrocarbons are important indices for delineating hydrocarbon prospects in the Songnan Low Uplift. Multifractal and spatial analysis techniques provide new ideas for index selection and comprehensive information extraction for oil and gas exploration.Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49358795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The NE–SW-trending graphite belt found in the Xinrong Region, Datong City is one the richest graphite reserves in China, extending for more than 22 km. The ore-bearing layer of the Huangtuyao Formation is a graphite-bearing gneiss. Based on major and trace element analysis data, we determined from three diagrams that the graphite-bearing gneiss is a parametamorphic rock, and this gneiss was formed by the regional metamorphism of carbonaceous argillite. The detritus of this ore deposit originated from an arc region as seen from the K2O/Na2O–SiO2 diagram. According to the Ta/Yb, Sr/Yb and K2O/Na2O ratios as well as the composition of Gehuyao gneiss, we concluded that this gneiss has typical low-potassium adakitic rock characteristics. Combined with the MgO/SiO2 diagram and the characteristics of low K2O and high Al2O3, the genetic model of Gehuyao gneiss is melted subducted oceanic crust. Based on regional geological data and comparison of samples, we found an inherent relationship in the main composition content between the graphite-bearing gneiss and the Gehuyao gneiss. This indicates that the ore deposit accumulated the weathering products of Gehuyao gneiss during the sedimentary period. This research provides evidence for ore body evolution and makes it possible to establish the sedimentary–metamorphic model of the graphite ore in this region. In light of the range of the ore body, we predict that the potential area for graphite mineralization in the North China Craton was 2 ± 1.5 km away from the boundary. Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis
{"title":"Geochemical characteristics and indication of graphite deposits in Xinrong Region, Shanxi, China","authors":"Yuqi Liang, Q. Xia, Yue Zhang, Yong Zhao","doi":"10.1144/geochem2021-086","DOIUrl":"https://doi.org/10.1144/geochem2021-086","url":null,"abstract":"The NE–SW-trending graphite belt found in the Xinrong Region, Datong City is one the richest graphite reserves in China, extending for more than 22 km. The ore-bearing layer of the Huangtuyao Formation is a graphite-bearing gneiss. Based on major and trace element analysis data, we determined from three diagrams that the graphite-bearing gneiss is a parametamorphic rock, and this gneiss was formed by the regional metamorphism of carbonaceous argillite. The detritus of this ore deposit originated from an arc region as seen from the K2O/Na2O–SiO2 diagram. According to the Ta/Yb, Sr/Yb and K2O/Na2O ratios as well as the composition of Gehuyao gneiss, we concluded that this gneiss has typical low-potassium adakitic rock characteristics. Combined with the MgO/SiO2 diagram and the characteristics of low K2O and high Al2O3, the genetic model of Gehuyao gneiss is melted subducted oceanic crust. Based on regional geological data and comparison of samples, we found an inherent relationship in the main composition content between the graphite-bearing gneiss and the Gehuyao gneiss. This indicates that the ore deposit accumulated the weathering products of Gehuyao gneiss during the sedimentary period. This research provides evidence for ore body evolution and makes it possible to establish the sedimentary–metamorphic model of the graphite ore in this region. In light of the range of the ore body, we predict that the potential area for graphite mineralization in the North China Craton was 2 ± 1.5 km away from the boundary. Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48665978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. McCurdy, J. Peter, M. Beth McClenaghan, M. Gadd, D. Layton-Matthews, M. Leybourne, R. Garrett, D. Petts, S. Jackson, Scott Casselman
The trace element composition of detrital magnetite grains recovered from six local streams around the Casino high-grade porphyry Cu–Au–Mo deposit, west-central Yukon, is compared with igneous and magmatic-hydrothermal magnetite recovered from mineralized and unmineralized host rocks at the deposit. Linear discriminant analysis of 12 elements (Mg, Al, Ti, V, Mn, Co, Cr, Ni, Cu, Zn, Ga and Ge) and plots of Ti v. Ni/Cr are used to discriminate between magmatic-hydrothermal magnetite from the potassic alteration zone and igneous magnetite from granodiorite and quartz monzonite hosting the deposit. Magmatic-hydrothermal magnetite with a trace element composition similar to that from the potassic alteration zone at Casino is identifiable in stream sediments draining the deposit. Copper in magmatic-hydrothermal magnetite, present as minute inclusions of sulfide minerals such as chalcopyrite or substituted within the magnetite crystal lattice, is a strong indicator of Cu mineralization. We show that the chemical compositions of magnetite recovered from stream sediments can be used to explore for porphyry systems. Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis Supplementary material: Laser ablation data for major, minor and trace elements in magnetite from bedrock and stream sediment samples from Casino are available at https://doi.org/10.6084/m9.figshare.c.5896900
{"title":"Evaluation of magnetite as an indicator mineral for porphyry Cu exploration: a case study using bedrock and stream sediments at the Casino porphyry Cu–Au–Mo deposit, Yukon, Canada","authors":"M. McCurdy, J. Peter, M. Beth McClenaghan, M. Gadd, D. Layton-Matthews, M. Leybourne, R. Garrett, D. Petts, S. Jackson, Scott Casselman","doi":"10.1144/geochem2021-072","DOIUrl":"https://doi.org/10.1144/geochem2021-072","url":null,"abstract":"The trace element composition of detrital magnetite grains recovered from six local streams around the Casino high-grade porphyry Cu–Au–Mo deposit, west-central Yukon, is compared with igneous and magmatic-hydrothermal magnetite recovered from mineralized and unmineralized host rocks at the deposit. Linear discriminant analysis of 12 elements (Mg, Al, Ti, V, Mn, Co, Cr, Ni, Cu, Zn, Ga and Ge) and plots of Ti v. Ni/Cr are used to discriminate between magmatic-hydrothermal magnetite from the potassic alteration zone and igneous magnetite from granodiorite and quartz monzonite hosting the deposit. Magmatic-hydrothermal magnetite with a trace element composition similar to that from the potassic alteration zone at Casino is identifiable in stream sediments draining the deposit. Copper in magmatic-hydrothermal magnetite, present as minute inclusions of sulfide minerals such as chalcopyrite or substituted within the magnetite crystal lattice, is a strong indicator of Cu mineralization. We show that the chemical compositions of magnetite recovered from stream sediments can be used to explore for porphyry systems. Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis Supplementary material: Laser ablation data for major, minor and trace elements in magnetite from bedrock and stream sediment samples from Casino are available at https://doi.org/10.6084/m9.figshare.c.5896900","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45010969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Owing to the strong control bedrock geology may exert on the chemical composition of stream sediments, the determination of stream sediment geochemical anomalies is always affected by the lithology background in areas with variable lithologies. In this study, the expectation–maximization (EM) algorithm was used to separate lithologies of different chemical compositions in a 1: 200 000 scale regional geochemical data set of stream sediments in a lithologically complex region in Hunan province, SE China. The data set included 1024 minerogenic stream sediment samples which were analysed for Cu, La, Li, Be, Cr, Ni, Sr, V, Th, Ti and Zr. A comparison between Cu anomalies determined with and without taking into account the separation of lithologies was carried out. The result shows that stream sediment geochemical anomalies in lithologically complex regions can be determined in a more reasonable way by application of the EM clustering method. Strong but false or meaningless anomalies can be eliminated, and weak but important or meaningful anomalies are more clearly revealed.
{"title":"Identification of stream sediment geochemical anomalies in lithologically complex regions: case study of Cu mineralization in Hunan province, SE China","authors":"Ya-Guang Sun, Libo Hao, Xinyun Zhao, Jilong Lu, Yanxiang Shi, Chengyou Ma, Qingquan Li, Qiaoqiao Wei","doi":"10.1144/geochem2021-096","DOIUrl":"https://doi.org/10.1144/geochem2021-096","url":null,"abstract":"Owing to the strong control bedrock geology may exert on the chemical composition of stream sediments, the determination of stream sediment geochemical anomalies is always affected by the lithology background in areas with variable lithologies. In this study, the expectation–maximization (EM) algorithm was used to separate lithologies of different chemical compositions in a 1: 200 000 scale regional geochemical data set of stream sediments in a lithologically complex region in Hunan province, SE China. The data set included 1024 minerogenic stream sediment samples which were analysed for Cu, La, Li, Be, Cr, Ni, Sr, V, Th, Ti and Zr. A comparison between Cu anomalies determined with and without taking into account the separation of lithologies was carried out. The result shows that stream sediment geochemical anomalies in lithologically complex regions can be determined in a more reasonable way by application of the EM clustering method. Strong but false or meaningless anomalies can be eliminated, and weak but important or meaningful anomalies are more clearly revealed.","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":"22 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63941012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Geochemical prospecting is an important and effective approach for discovering mineral deposits. Collection, management, visualization, interpretation, modelling and publishing of geochemical survey data remain challenging. The main aim of this study is to illustrate the application of Google Earth in the visualization and interpretation of geochemical survey data using a dataset collected from the Daqiao district, Gansu Province, China. Google Earth, a free web-based program that provides a rich set of global images along with satellite and map data, can be applied to design geochemical sampling strategies, display geochemical sampling location landscapes, collect and manage geochemical survey data, visualize and publish 0D (point), 1D (profile), 2D (raster map) and 3D (superposition of multiple maps) geochemical maps, and interpret and model geochemical patterns using various Google Earth functions and the Keyhole Markup Language. Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis
{"title":"Google Earth-aided visualization and interpretation of geochemical survey data","authors":"R. Zuo, Bojun Yin","doi":"10.1144/geochem2021-079","DOIUrl":"https://doi.org/10.1144/geochem2021-079","url":null,"abstract":"Geochemical prospecting is an important and effective approach for discovering mineral deposits. Collection, management, visualization, interpretation, modelling and publishing of geochemical survey data remain challenging. The main aim of this study is to illustrate the application of Google Earth in the visualization and interpretation of geochemical survey data using a dataset collected from the Daqiao district, Gansu Province, China. Google Earth, a free web-based program that provides a rich set of global images along with satellite and map data, can be applied to design geochemical sampling strategies, display geochemical sampling location landscapes, collect and manage geochemical survey data, visualize and publish 0D (point), 1D (profile), 2D (raster map) and 3D (superposition of multiple maps) geochemical maps, and interpret and model geochemical patterns using various Google Earth functions and the Keyhole Markup Language. Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2022-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43353019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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