I. N. Myagkaya, B. Saryg-ool, O. N. Surkov, S. Zhmodik, E. Lazareva, O. Taran
We study the contents of elements and group composition in natural organic matter (NOM) that interacts with acid mine drainage (АMD) and high-sulfide tailings at the Ursk site (southwestern Siberia, Russia). AMD causes biomass changes in NOM, related changes in the composition of fractions, and hydrolysis of hydrolyzable compounds; it increases the water-soluble fraction and maintains depolymerization of humic acids to fulvic acids, but exerts no effect on substances soluble in organics (bitumen) or on poorly hydrolyzable compounds. Accumulation of inorganic elements and precipitation of minerals obscure the true fraction composition of NOM: the superposed mineral component contributes significantly to the water-soluble, humic acid, hydrolyzable and non-hydrolyzable fractions, and may reach 26.4% per total of all fractions. Rock-forming and potentially toxic elements partition among NOM fractions and predominate in the water-soluble fraction. The contents of Au and Ag are the highest in the fractions of humic acids and hydrolyzable compounds but are lower in the non-hydrolyzable residue. The obtained data have implications for possible migration of potentially toxic elements and noble metals and thus for remediation of polluted areas. The observed fractionation of Ag and Au in NOM helps us to understand the mechanisms of their distribution in organic-bearing environments, such as peatlands or coal basins.
{"title":"Natural organic matter from the dispersion train of gold sulfide tailings: group composition and fractionation of elements: case study of Ursk Tailings, Kemerovo Region, Siberia","authors":"I. N. Myagkaya, B. Saryg-ool, O. N. Surkov, S. Zhmodik, E. Lazareva, O. Taran","doi":"10.1144/geochem2020-052","DOIUrl":"https://doi.org/10.1144/geochem2020-052","url":null,"abstract":"We study the contents of elements and group composition in natural organic matter (NOM) that interacts with acid mine drainage (АMD) and high-sulfide tailings at the Ursk site (southwestern Siberia, Russia). AMD causes biomass changes in NOM, related changes in the composition of fractions, and hydrolysis of hydrolyzable compounds; it increases the water-soluble fraction and maintains depolymerization of humic acids to fulvic acids, but exerts no effect on substances soluble in organics (bitumen) or on poorly hydrolyzable compounds. Accumulation of inorganic elements and precipitation of minerals obscure the true fraction composition of NOM: the superposed mineral component contributes significantly to the water-soluble, humic acid, hydrolyzable and non-hydrolyzable fractions, and may reach 26.4% per total of all fractions. Rock-forming and potentially toxic elements partition among NOM fractions and predominate in the water-soluble fraction. The contents of Au and Ag are the highest in the fractions of humic acids and hydrolyzable compounds but are lower in the non-hydrolyzable residue. The obtained data have implications for possible migration of potentially toxic elements and noble metals and thus for remediation of polluted areas. The observed fractionation of Ag and Au in NOM helps us to understand the mechanisms of their distribution in organic-bearing environments, such as peatlands or coal basins.","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2020-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46995808","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 Patterson Lake corridor is situated along the SW margin of the Athabasca Basin and contains several basement-hosted uranium deposits and prospects. Drill core investigations during this study have determined that granite, granodiorite, mafic and alkali intrusive basement rocks are entrained in a deep-seated NE-striking subvertical heterogeneous high-strain zone defined by anastomosing ductile to semi-brittle shears and brittle faults. The earliest phases of ductile deformation (D1/D2), linked with Taltson (1.94–1.92 Ga) orogenesis, involved interference between early fold sets (F1/F2) and development of an associated ductile transposition foliation (S1/S2). During subsequent Snowbird (c. 1.91–1.90 Ga) tectonism, this composite foliation was re-folded (D3) by NE-trending buckle-style folds (F3), including a regional fold centred on the Clearwater aeromagnetic high. In continuum with D3, a network of dextral-reverse chloritic-graphitic shears, with C–S geometry, formed initially (D4a) and progressed to more discrete, spaced semi-brittle structures (D4b; c. 1.900–1.819 Ga). Basin development (D5a;
{"title":"Structural evolution and related implications for uranium mineralization in the Patterson Lake corridor, southwestern Athabasca Basin, Saskatchewan, Canada","authors":"D. Johnstone, K. Bethune, C. Card, V. Tschirhart","doi":"10.1144/geochem2020-030","DOIUrl":"https://doi.org/10.1144/geochem2020-030","url":null,"abstract":"The Patterson Lake corridor is situated along the SW margin of the Athabasca Basin and contains several basement-hosted uranium deposits and prospects. Drill core investigations during this study have determined that granite, granodiorite, mafic and alkali intrusive basement rocks are entrained in a deep-seated NE-striking subvertical heterogeneous high-strain zone defined by anastomosing ductile to semi-brittle shears and brittle faults. The earliest phases of ductile deformation (D1/D2), linked with Taltson (1.94–1.92 Ga) orogenesis, involved interference between early fold sets (F1/F2) and development of an associated ductile transposition foliation (S1/S2). During subsequent Snowbird (c. 1.91–1.90 Ga) tectonism, this composite foliation was re-folded (D3) by NE-trending buckle-style folds (F3), including a regional fold centred on the Clearwater aeromagnetic high. In continuum with D3, a network of dextral-reverse chloritic-graphitic shears, with C–S geometry, formed initially (D4a) and progressed to more discrete, spaced semi-brittle structures (D4b; c. 1.900–1.819 Ga). Basin development (D5a; <c. 1.819 Ga) was marked by a set of north-striking normal faults and related east- and NE-striking transfer faults that accommodated subsidence. Primary uranium mineralization (D5b; c. 1.45 Ga) was facilitated by brittle reactivation of NE-striking basement shears in response to WSW–ENE-directed compressional stress (σ1). Uraninite was emplaced along σ1-parallel extension fractures and dilational zones formed at linkages between NE- and ENE-striking dextral strike-slip faults. Uranium remobilization (D5c) occurred after σ1 shifted to WNW–ESE, giving rise to regional east- and SE-striking conjugate faults, along which mafic dykes (1.27 and 1.16 Ga) intruded. Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathways","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":"21 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2020-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41623396","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 Patterson Lake corridor in the Athabasca Basin region of Saskatchewan, Canada, hosts a large-scale uranium system with two major deposits already delineated. The corridor developed in crystalline rocks of the SW Rae Province, which host all of the known uranium endowment. Orthogneisses along with voluminous pegmatites are the hosts of the uranium mineralization. These rocks, however, underwent significant open-system metasomatic–hydrothermal modification. Principal amongst these alterations is early and pervasive quartz flooding that resulted in the development of widespread secondary quartzites and associated rock types. These secondary quartzites and their altered host rocks suffered ductile deformation, typically focused at silicification fronts. Late carbonatite dykes exploited the associated shear zones. Semi-brittle deformation zones nucleated near the previously developed ductile high-strain zones. Graphite and associated iron-sulfides precipitated in a semi-brittle structural regime. These graphitized zones provided the necessary structural architecture to focus the uranium system, which exploited the conduit hundreds of millions of years later at c. 1.425 Ga. Host rocks of the Patterson Lake corridor prove that metasedimentary rocks are not a requirement for the development of giant Proterozoic unconformity uranium deposits. Crustal-scale fault zones with access to the mantle (i.e. carbonatites) should be considered a key parameter in the exploration model for Proterozoic unconformity uranium deposits. Given the similarity of the mineral assemblages in the crystalline basement rocks of the main exploration corridor in the eastern Athabasca Basin region, it is likely that a similar, cryptic geological boundary focused the giant uranium system in that region. Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathways
{"title":"The Patterson Lake corridor of Saskatchewan, Canada: defining crystalline rocks in a deep-seated structure that hosts a giant, high-grade Proterozoic unconformity uranium system","authors":"C. Card","doi":"10.1144/geochem2020-007","DOIUrl":"https://doi.org/10.1144/geochem2020-007","url":null,"abstract":"The Patterson Lake corridor in the Athabasca Basin region of Saskatchewan, Canada, hosts a large-scale uranium system with two major deposits already delineated. The corridor developed in crystalline rocks of the SW Rae Province, which host all of the known uranium endowment. Orthogneisses along with voluminous pegmatites are the hosts of the uranium mineralization. These rocks, however, underwent significant open-system metasomatic–hydrothermal modification. Principal amongst these alterations is early and pervasive quartz flooding that resulted in the development of widespread secondary quartzites and associated rock types. These secondary quartzites and their altered host rocks suffered ductile deformation, typically focused at silicification fronts. Late carbonatite dykes exploited the associated shear zones. Semi-brittle deformation zones nucleated near the previously developed ductile high-strain zones. Graphite and associated iron-sulfides precipitated in a semi-brittle structural regime. These graphitized zones provided the necessary structural architecture to focus the uranium system, which exploited the conduit hundreds of millions of years later at c. 1.425 Ga. Host rocks of the Patterson Lake corridor prove that metasedimentary rocks are not a requirement for the development of giant Proterozoic unconformity uranium deposits. Crustal-scale fault zones with access to the mantle (i.e. carbonatites) should be considered a key parameter in the exploration model for Proterozoic unconformity uranium deposits. Given the similarity of the mineral assemblages in the crystalline basement rocks of the main exploration corridor in the eastern Athabasca Basin region, it is likely that a similar, cryptic geological boundary focused the giant uranium system in that region. Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathways","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2020-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45956591","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}
Irene M. Kadel-Harder, P. Spry, Audrey L. McCombs, Haozhe Zhang
The Cripple Creek alkaline igneous rock-related, low-sulfidation epithermal gold telluride deposit, Colorado, is hosted in the 10 km wide Oligocene alkaline volcanic Cripple Creek diatreme in Proterozoic rocks. Gold occurs as native gold, Au-tellurides, and in the structure of arsenian pyrite, in potassically altered high-grade veins, and as disseminations in the host rocks. Correlation coefficients, principal component analysis, hierarchical cluster analysis and random forests were used to analyse major and trace element compositions of 995 rock samples primarily from low-grade gold mineralization in drill core from three currently operating pits (Wild Horse Extension, Globe Hill and Schist Island) in the northwestern part of the Cripple Creek diatreme. These methods suggest that Ag, As, Bi, Te and W are the best pathfinders to gold mineralization in low-grade disseminated ore. Although Mo correlates with gold in other studies and is spatially related to gold veins, molybdenite post-dated the formation of gold and is likely related to a late-stage porphyry overprint. These elements, in conjunction with mineralogical studies, indicate that tellurides, fluorite, quartz, carbonates, roscoelite, tennantite-tetrahedrite, pyrite, sphalerite, muscovite, monazite, bastnäsite and hübnerite serve as exploration guides to ore.
{"title":"Identifying pathfinder elements for gold in bulk-rock geochemical data from the Cripple Creek Au–Te deposit: a statistical approach","authors":"Irene M. Kadel-Harder, P. Spry, Audrey L. McCombs, Haozhe Zhang","doi":"10.1144/geochem2020-048","DOIUrl":"https://doi.org/10.1144/geochem2020-048","url":null,"abstract":"The Cripple Creek alkaline igneous rock-related, low-sulfidation epithermal gold telluride deposit, Colorado, is hosted in the 10 km wide Oligocene alkaline volcanic Cripple Creek diatreme in Proterozoic rocks. Gold occurs as native gold, Au-tellurides, and in the structure of arsenian pyrite, in potassically altered high-grade veins, and as disseminations in the host rocks. Correlation coefficients, principal component analysis, hierarchical cluster analysis and random forests were used to analyse major and trace element compositions of 995 rock samples primarily from low-grade gold mineralization in drill core from three currently operating pits (Wild Horse Extension, Globe Hill and Schist Island) in the northwestern part of the Cripple Creek diatreme. These methods suggest that Ag, As, Bi, Te and W are the best pathfinders to gold mineralization in low-grade disseminated ore. Although Mo correlates with gold in other studies and is spatially related to gold veins, molybdenite post-dated the formation of gold and is likely related to a late-stage porphyry overprint. These elements, in conjunction with mineralogical studies, indicate that tellurides, fluorite, quartz, carbonates, roscoelite, tennantite-tetrahedrite, pyrite, sphalerite, muscovite, monazite, bastnäsite and hübnerite serve as exploration guides to ore.","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2020-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47963353","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}
In this study we apply multivariate statistical and predictive classification methods to interpret geochemical data from 8545 stream-sediment samples collected in southern British Columbia, Canada. Data for 35 elements were corrected for laboratory bias and adjusted for values reported below the lower limit of detection. Each sample site was attributed with the closest British Columbia MINFILE occurrence within 2.5 km. MINFILE occurrences were grouped into ‘GroupModels’ based on similarities between the British Columbia Geological Survey mineral deposit models and geochemical signatures. These data were used to create a training dataset of 474 observations, including 100 samples not attributed with a MINFILE occurrence. The training set was used to generate predictions for the mineral deposit models from which posterior probabilities were estimated for the remaining 8071 samples. The data underwent a centred log-ratio transformation and then characterization using either principal component analysis (PCA) or t-distributed stochastic neighbour embedding using 9 dimensions (t-SNE) prior to classification by random forests. The posterior probabilities generated from the t-SNE metric provide a slightly higher level of prediction accuracy compared to the posterior probabilities obtained using the PCA metric. The results are comparable to those obtained using a conventional catchment analysis approach and expert-driven model. The approach presented here provides a repeatable, consistent and defensible methodology for the identification of prospective mineralized terrains and mineral systems.
{"title":"Mineral-resource prediction using advanced data analytics and machine learning of the QUEST-South stream-sediment geochemical data, southwestern British Columbia, Canada","authors":"E. Grunsky, D. Arne","doi":"10.1144/geochem2020-054","DOIUrl":"https://doi.org/10.1144/geochem2020-054","url":null,"abstract":"In this study we apply multivariate statistical and predictive classification methods to interpret geochemical data from 8545 stream-sediment samples collected in southern British Columbia, Canada. Data for 35 elements were corrected for laboratory bias and adjusted for values reported below the lower limit of detection. Each sample site was attributed with the closest British Columbia MINFILE occurrence within 2.5 km. MINFILE occurrences were grouped into ‘GroupModels’ based on similarities between the British Columbia Geological Survey mineral deposit models and geochemical signatures. These data were used to create a training dataset of 474 observations, including 100 samples not attributed with a MINFILE occurrence. The training set was used to generate predictions for the mineral deposit models from which posterior probabilities were estimated for the remaining 8071 samples. The data underwent a centred log-ratio transformation and then characterization using either principal component analysis (PCA) or t-distributed stochastic neighbour embedding using 9 dimensions (t-SNE) prior to classification by random forests. The posterior probabilities generated from the t-SNE metric provide a slightly higher level of prediction accuracy compared to the posterior probabilities obtained using the PCA metric. The results are comparable to those obtained using a conventional catchment analysis approach and expert-driven model. The approach presented here provides a repeatable, consistent and defensible methodology for the identification of prospective mineralized terrains and mineral systems.","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2020-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/geochem2020-054","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47258321","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}
Yu Guo, W. Gang, G. Gao, Shangru Yang, C. Jiang, Guo Chen, Chuanzhen Zhu, Xiaofeng Li, Yifan Wang, Yue-xia Dong, K. Goldberg
Paleogene sediments, especially the third member of the Dongying Formation (Ed3) and the first and third members of the Shahejie Formation (Es1 and Es3), have been regarded as the most important source rocks in the Nanpu Sag. Organic and inorganic analyses, including Rock-Eval pyrolysis, gas chromatography-mass spectrometry, and element geochemistry, in 91 mudstone samples, were used to reconstruct the palaeoenvironmental conditions, such as palaeoclimate, palaeo-salinity and palaeo-redox conditions, and to recognize the origin of organic matter. The results show that Es3 has a higher TOC content than Es1 and Ed3. Hydrocarbon genetic potential (S1 + S2) of the samples indicate fair to good hydrocarbon potential. The kerogen type of Ed3 and Es1 source rocks are Type II1–II2, while Es3 source rocks are dominated by Type II2–III kerogens. Biomarkers and inorganic geochemical indicatives of source rocks, such as Pr/Ph, V/(V + Ni) and Cu/Zn, indicate a lacustrine environment with fresh to brackish water under suboxic to anoxic conditions during deposition. Ed3 source rocks are characterized by low G/C30H (gamacerane/C30hopane) (<0.1), TT/C30H (tricyclic terpane/C30hopane) and S/H (serane/hopane), high Pr/Ph (pristane/phytane) and C24TeT/C23TT (C24tetracyclic terpane/C23tricyclic terpane), indicating mixed input of both algae and terrestrial higher plants, dominated by terrestrial higher plants. Es1 source rocks display medium G/C30H, TT/C30H, S/H, Pr/Ph and C24TeT/C23TT, indicative of a mixed input of both algae and terrestrial higher plants. Es3 source rocks are characterized by high G/C30H (>0.1), TT/C30H and S/H, low Pr/Ph and C24TeT/C23TT, typical of a mixed input of algae and terrestrial higher plants, with algal dominance. Ed3, Es1 and Es3 source rocks were mostly deposited in semi-arid to humid-warm climate conditions, with an average temperature higher than 15°C. This study suggests that suitable temperatures, a fresh to brackish lacustrine environment and suboxic to anoxic conditions could result in a high organic matter concentration and preservation, thus providing prerequisites for the formation of high-quality source rocks. Supplementary material: Tables S1–S3 are available at https://doi.org/10.6084/m9.figshare.c.5227684
{"title":"An integrated organic–inorganic geochemical characterization of Paleogene sediments in No.1 Structural Belt of the Nanpu Sag, Bohai Bay Basin, eastern China: implications for the origin of organic matter","authors":"Yu Guo, W. Gang, G. Gao, Shangru Yang, C. Jiang, Guo Chen, Chuanzhen Zhu, Xiaofeng Li, Yifan Wang, Yue-xia Dong, K. Goldberg","doi":"10.1144/geochem2019-060","DOIUrl":"https://doi.org/10.1144/geochem2019-060","url":null,"abstract":"Paleogene sediments, especially the third member of the Dongying Formation (Ed3) and the first and third members of the Shahejie Formation (Es1 and Es3), have been regarded as the most important source rocks in the Nanpu Sag. Organic and inorganic analyses, including Rock-Eval pyrolysis, gas chromatography-mass spectrometry, and element geochemistry, in 91 mudstone samples, were used to reconstruct the palaeoenvironmental conditions, such as palaeoclimate, palaeo-salinity and palaeo-redox conditions, and to recognize the origin of organic matter. The results show that Es3 has a higher TOC content than Es1 and Ed3. Hydrocarbon genetic potential (S1 + S2) of the samples indicate fair to good hydrocarbon potential. The kerogen type of Ed3 and Es1 source rocks are Type II1–II2, while Es3 source rocks are dominated by Type II2–III kerogens. Biomarkers and inorganic geochemical indicatives of source rocks, such as Pr/Ph, V/(V + Ni) and Cu/Zn, indicate a lacustrine environment with fresh to brackish water under suboxic to anoxic conditions during deposition. Ed3 source rocks are characterized by low G/C30H (gamacerane/C30hopane) (<0.1), TT/C30H (tricyclic terpane/C30hopane) and S/H (serane/hopane), high Pr/Ph (pristane/phytane) and C24TeT/C23TT (C24tetracyclic terpane/C23tricyclic terpane), indicating mixed input of both algae and terrestrial higher plants, dominated by terrestrial higher plants. Es1 source rocks display medium G/C30H, TT/C30H, S/H, Pr/Ph and C24TeT/C23TT, indicative of a mixed input of both algae and terrestrial higher plants. Es3 source rocks are characterized by high G/C30H (>0.1), TT/C30H and S/H, low Pr/Ph and C24TeT/C23TT, typical of a mixed input of algae and terrestrial higher plants, with algal dominance. Ed3, Es1 and Es3 source rocks were mostly deposited in semi-arid to humid-warm climate conditions, with an average temperature higher than 15°C. This study suggests that suitable temperatures, a fresh to brackish lacustrine environment and suboxic to anoxic conditions could result in a high organic matter concentration and preservation, thus providing prerequisites for the formation of high-quality source rocks. Supplementary material: Tables S1–S3 are available at https://doi.org/10.6084/m9.figshare.c.5227684","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2020-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/geochem2019-060","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41983668","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 major target of this research is the classification of pyrite types using fractal and stepwise factor analyses in the Chah Zard ore deposit, Central Iran. The ore occurs within a breccia/vein type and the major ore mineral hosting gold mineralization is pyrite. In this study, data were selected using optical, scanning electron microscopy (SEM) and backscattered electron observations as well as laser ablation-inductively coupled plasma–mass spectrometry (LA-ICP–MS) analysis. Conventional interpretations represent four gold-bearing pyrite types of various textures including fractured and porous Py1, oscillatory-rimmed and simple-zoned Py2, colloform Py3 and inclusion-rich Py4. The stepwise factor process was performed on the centred log ratio (clr) transformed data in two phases and Au was grouped with As, Te, Ni and Co in the second factor from the second stage (F2-2). Also, C-N fractal modelling was performed on the As, Au, Te and F2-2 values, all of which demonstrate multifractal nature. Four populations were separated based on F2-2 values and the C-N log–log plot. The main gold mineralization starts from 32 ppm, 2.8%, 7.94 ppm and 1.26 for Au, As, Te concentrations and F2-2, respectively, based on the C-N fractal modelling. These values are correlated with inclusion-rich Py4 and simple-zoned and oscillatory-rimmed Py2. The results obtained in this study show that fractal interpretation of LA-ICP–MS data by stepwise factor analysis may provide a suitable tool for the recognition of ore mineralization in epithermal gold deposits.
{"title":"Classification of pyrite types using fractal and stepwise factor analyses in the Chah Zard gold-silver epithermal deposit, Central Iran","authors":"H. Kouhestani, M. Ghaderi, P. Afzal, K. Zaw","doi":"10.1144/geochem2020-031","DOIUrl":"https://doi.org/10.1144/geochem2020-031","url":null,"abstract":"The major target of this research is the classification of pyrite types using fractal and stepwise factor analyses in the Chah Zard ore deposit, Central Iran. The ore occurs within a breccia/vein type and the major ore mineral hosting gold mineralization is pyrite. In this study, data were selected using optical, scanning electron microscopy (SEM) and backscattered electron observations as well as laser ablation-inductively coupled plasma–mass spectrometry (LA-ICP–MS) analysis. Conventional interpretations represent four gold-bearing pyrite types of various textures including fractured and porous Py1, oscillatory-rimmed and simple-zoned Py2, colloform Py3 and inclusion-rich Py4. The stepwise factor process was performed on the centred log ratio (clr) transformed data in two phases and Au was grouped with As, Te, Ni and Co in the second factor from the second stage (F2-2). Also, C-N fractal modelling was performed on the As, Au, Te and F2-2 values, all of which demonstrate multifractal nature. Four populations were separated based on F2-2 values and the C-N log–log plot. The main gold mineralization starts from 32 ppm, 2.8%, 7.94 ppm and 1.26 for Au, As, Te concentrations and F2-2, respectively, based on the C-N fractal modelling. These values are correlated with inclusion-rich Py4 and simple-zoned and oscillatory-rimmed Py2. The results obtained in this study show that fractal interpretation of LA-ICP–MS data by stepwise factor analysis may provide a suitable tool for the recognition of ore mineralization in epithermal gold deposits.","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":"20 1","pages":"496 - 508"},"PeriodicalIF":2.4,"publicationDate":"2020-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/geochem2020-031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46022496","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}
Xin Peng, Y. Deng, Xiangdan Zhang, Lu Liu, Jian Hu, Xianqian Duan, Zhicheng Wei, Qi Feng, Ke Shen
Phosphogypsum (PG) is an acid by-product from the production phosphate fertilizers that is produced in large amounts all over the world. However, it is challenging to reuse this waste due to the quantities of various impurities in PG and technical restrictions, resulting in PG accumulation, which threatens adjacent environments. To reduce PG storage and safely utilize PG, the aim of our study was to define the leaching characteristics of the impurities present in PG under different conditions. We found that (1) different leaching experiments showed different leachate profiles (including pH and electrical conductivity values of leachate), which indicated that the liquid/solid (L/S) ratio, temperature, oscillation strength, particle size, and pH have remarkable effects on the concentration of leached impurities; (2) all leachate (i.e. soluble P, fluoride, Zn, Pb, As, and Hg) extraction concentrations were significantly more sensitive to the effect of the L/S ratio and pH than the effect of the other conditions; and (3) the leaching concentration was strongly influenced by pH, and a strong correlation among soluble P, F, As, and Hg concentrations in the leachate was demonstrated by a correlation analysis. In the present study, we revealed a systematic leaching mechanism of potential toxic elements in PG and have provided guidance and a reference for PG resource comprehensive utilization and surrounding environment treatment. Supplementary material: Chemical compositions of the phosphogypsum and pairwise Wilcoxon test results are available at https://doi.org/10.6084/m9.figshare.c.5088187
{"title":"The leaching characteristics of common toxic elements in phosphogypsum","authors":"Xin Peng, Y. Deng, Xiangdan Zhang, Lu Liu, Jian Hu, Xianqian Duan, Zhicheng Wei, Qi Feng, Ke Shen","doi":"10.1144/geochem2019-062","DOIUrl":"https://doi.org/10.1144/geochem2019-062","url":null,"abstract":"Phosphogypsum (PG) is an acid by-product from the production phosphate fertilizers that is produced in large amounts all over the world. However, it is challenging to reuse this waste due to the quantities of various impurities in PG and technical restrictions, resulting in PG accumulation, which threatens adjacent environments. To reduce PG storage and safely utilize PG, the aim of our study was to define the leaching characteristics of the impurities present in PG under different conditions. We found that (1) different leaching experiments showed different leachate profiles (including pH and electrical conductivity values of leachate), which indicated that the liquid/solid (L/S) ratio, temperature, oscillation strength, particle size, and pH have remarkable effects on the concentration of leached impurities; (2) all leachate (i.e. soluble P, fluoride, Zn, Pb, As, and Hg) extraction concentrations were significantly more sensitive to the effect of the L/S ratio and pH than the effect of the other conditions; and (3) the leaching concentration was strongly influenced by pH, and a strong correlation among soluble P, F, As, and Hg concentrations in the leachate was demonstrated by a correlation analysis. In the present study, we revealed a systematic leaching mechanism of potential toxic elements in PG and have provided guidance and a reference for PG resource comprehensive utilization and surrounding environment treatment. Supplementary material: Chemical compositions of the phosphogypsum and pairwise Wilcoxon test results are available at https://doi.org/10.6084/m9.figshare.c.5088187","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":"20 1","pages":"473 - 479"},"PeriodicalIF":2.4,"publicationDate":"2020-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/geochem2019-062","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47260167","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}
Laboratory-dried specimens yield distorted information about the state of hydromorphic soil. Changes in the gas medium, humidity, temperature, aggregation capacity and illumination have an irreversible impact on the dried and powdered soil specimen. Properties of the dried hydromorphic soil can be altered significantly. Most altered are (1) the colour of the hydromorphic soils, (2) the рН value, and (3) the content of mobile trace metal (TM) compounds after drying the wet soil. Colour change (browning) of the hydromorphic soil is related to the oxidation of Fe(II). In a highly ferruginous soil, the browning is rapid and visible even to the naked eye. In the weakly ferruginous gley, the colour change is invisible to the naked eye, but instrumental field measurements reveal a slow and slight yellowing of the dried gley. In dried soils, laboratory рН values determined in soil suspension differ from the values determined in soil solution at the same time. The process of drying provokes a significant decrease in the content of mobile TM compounds, resulting in the illusion of less soil contamination than the real situation during hydromorphic soil humidification. When studying hydromorphic soils, it is desirable to accomplish the maximum possible field measurements. Laboratory analyses should only be carried out for specimens stored under dark conditions since they retain the initial humidity, temperature and gas composition.
{"title":"Changing the properties of samples after extraction from wet soil: a short review","authors":"Y. Vodyanitskii, T. Minkina","doi":"10.1144/geochem2020-033","DOIUrl":"https://doi.org/10.1144/geochem2020-033","url":null,"abstract":"Laboratory-dried specimens yield distorted information about the state of hydromorphic soil. Changes in the gas medium, humidity, temperature, aggregation capacity and illumination have an irreversible impact on the dried and powdered soil specimen. Properties of the dried hydromorphic soil can be altered significantly. Most altered are (1) the colour of the hydromorphic soils, (2) the рН value, and (3) the content of mobile trace metal (TM) compounds after drying the wet soil. Colour change (browning) of the hydromorphic soil is related to the oxidation of Fe(II). In a highly ferruginous soil, the browning is rapid and visible even to the naked eye. In the weakly ferruginous gley, the colour change is invisible to the naked eye, but instrumental field measurements reveal a slow and slight yellowing of the dried gley. In dried soils, laboratory рН values determined in soil suspension differ from the values determined in soil solution at the same time. The process of drying provokes a significant decrease in the content of mobile TM compounds, resulting in the illusion of less soil contamination than the real situation during hydromorphic soil humidification. When studying hydromorphic soils, it is desirable to accomplish the maximum possible field measurements. Laboratory analyses should only be carried out for specimens stored under dark conditions since they retain the initial humidity, temperature and gas composition.","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":"20 1","pages":"399 - 407"},"PeriodicalIF":2.4,"publicationDate":"2020-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/geochem2020-033","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42819438","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 exploration for rare metals, specifically lithium, is essential on a regional scale based on their demand and consumption in recent years. The main objective of this study was to delineate lithium anomalies in regional exploration utilizing the geochemical mapping prospectivity index (GMPI), staged factor analysis (SFA), and a concentration-number (C-N) fractal model based on stream sediments. The case study area is 26000 km2 and is located in the Khorasan Razavi province (NE Iran). In addition, rock samples were used to validate the Li anomalies identified. Results derived via the SFA show that Li was located on a factor denoted as F1-3 with Be, Cs, F, Nb, Sn, Th, U and W, which was used for calculation of the GMPI values. The GMPI data were classified by the C-N fractal method for determination of the Li anomalies. The main anomalies with GMPI ≥ 0.7 and Li ≥ 48 ppm were situated in the SE, SW, north and south parts of the study region. Li grades of rock samples were categorized by the C-N fractal technique for validation of F2-2 anomalies using a log-ratio matrix. The main anomalies were correlated with related lithological units of Li mineralization types. This correlation indicates that the main GMPI–Li anomalies are associated with granitic–pegmatitic units in the central and SE parts, and overlap with clay minerals in the northern and southern sectors of this region. There is good potential for Li mineralization as demonstrated by this hybrid method.
{"title":"Geochemical exploration for lithium in NE Iran using the geochemical mapping prospectivity index, staged factor analysis, and a fractal model","authors":"H. Saadati, P. Afzal, H. Torshizian, A. Solgi","doi":"10.1144/geochem2020-020","DOIUrl":"https://doi.org/10.1144/geochem2020-020","url":null,"abstract":"Geochemical exploration for rare metals, specifically lithium, is essential on a regional scale based on their demand and consumption in recent years. The main objective of this study was to delineate lithium anomalies in regional exploration utilizing the geochemical mapping prospectivity index (GMPI), staged factor analysis (SFA), and a concentration-number (C-N) fractal model based on stream sediments. The case study area is 26000 km2 and is located in the Khorasan Razavi province (NE Iran). In addition, rock samples were used to validate the Li anomalies identified. Results derived via the SFA show that Li was located on a factor denoted as F1-3 with Be, Cs, F, Nb, Sn, Th, U and W, which was used for calculation of the GMPI values. The GMPI data were classified by the C-N fractal method for determination of the Li anomalies. The main anomalies with GMPI ≥ 0.7 and Li ≥ 48 ppm were situated in the SE, SW, north and south parts of the study region. Li grades of rock samples were categorized by the C-N fractal technique for validation of F2-2 anomalies using a log-ratio matrix. The main anomalies were correlated with related lithological units of Li mineralization types. This correlation indicates that the main GMPI–Li anomalies are associated with granitic–pegmatitic units in the central and SE parts, and overlap with clay minerals in the northern and southern sectors of this region. There is good potential for Li mineralization as demonstrated by this hybrid method.","PeriodicalId":55114,"journal":{"name":"Geochemistry-Exploration Environment Analysis","volume":"20 1","pages":"461 - 472"},"PeriodicalIF":2.4,"publicationDate":"2020-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/geochem2020-020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41499843","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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