JournalTOCs

Geochemistry : Exploration, Environment, Analysis
Journal Prestige (SJR): 0.543

Citation Impact (citeScore): 2
Number of Followers: 6

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1467-7873 - ISSN (Online) 2041-4943
Published by Geological Society of London

[9 journals]

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
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  Authors: McCurdy MW; Peter JM, McClenaghan M, et al.
  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-analysisSupplementary 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
  PubDate: Fri, 06 May 2022 00:00:00 GMT
Geochemical characteristics and indication of graphite deposits in Xinrong
Region, Shanxi, China
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  Authors: Liang Y; Xia Q, Zhang Y, et al.
  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
  PubDate: Wed, 04 May 2022 00:00:00 GMT
Identification of stream sediment geochemical anomalies in lithologically
complex regions: case study of Cu mineralization in Hunan province, SE
China
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  Authors: Sun Y; Hao L, Zhao X, et al.
  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.
  PubDate: Thu, 07 Apr 2022 00:00:00 GMT
Google Earth-aided visualization and interpretation of geochemical survey
data
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  Authors: Zuo R; Yin B.
  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
  PubDate: Thu, 31 Mar 2022 00:00:00 GMT
Comparison of groundwater composition from the Monturaqui and Punta Negra
Basins, northern Chile: implications for porphyry copper exploration
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  Authors: Rissmann CF; Leybourne MI, Benn CC, et al.
  Abstract: Groundwaters recovered from the Salar de Punta Negra and Monturaqui basins in the Atacama Desert of northern Chile exhibit distinctly different isotopic, major, trace, and porphyry copper elemental compositions related to contrasting morphostructural, geochemical, and hydrodynamic settings. Comparison of these distinct groundwater signatures with groundwaters from known porphyry copper deposits (Salar de Hamburgo and Spence Deposit), can be used to determine if either basin might be prospective for porphyry copper mineralization. Groundwaters within the Punta Negra Basin exhibit geochemical characteristics consistent with other closed basin settings throughout the arid Andes. Elemental and isotopic compositions within the Punta Negra Basin reflect closed basin evaporitic processes consistent with the hyperarid, volcanic setting of the central Andes. Pathfinder metals and isotopic compositions are not consistent with porphyry copper type mineralization as described for groundwaters within the Salar de Hamburgo Basin, and the Spence Deposit. Within the Monturaqui Basin the geochemical composition of groundwaters are characteristic of diffuse hydrothermal activity. Sulfur isotopic composition within the waters of the northern Monturaqui Basin exhibit δ34SCDT isotopic signatures that fall within the range for sulfide mineralization as reported for groundwaters in and around the Spence Deposit and the Salar de Hamburgo. However, porphyry copper related elements within the Monturaqui Basin are impoverished relative to groundwaters of the Spence and Escondida Deposit. Such impoverishment in porphyry related elements, taken in conjunction with enriched δ13CPDB compositions, elevated groundwater temperatures, groundwater compositions dominated by HCO3, SO4, and Si, and the proximity of the Monturaqui Basin to the current magmatic arc are consistent with a volcanic hydrothermal origin. In summary, the groundwater geochemistry of the Monturaqui and Punta Negra Basins are not indicative of porphyry copper-type mineralization.Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
  PubDate: Thu, 31 Mar 2022 00:00:00 GMT
Controls on groundwater selenium, arsenic and base metals in groundwater
around a selenium-bearing volcanogenic massive sulfide deposit:
constraints from stable isotopes, trace elements and redox controls
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  Authors: Leybourne MI; Layton-Matthews D, Peter JM, et al.
  Abstract: Understanding the controls on the behaviour of metalloids (Se, As) and metals (Cu, Zn, Pb) in natural aqueous systems is vital to interpreting hydrogeochemical data in environmental and mineral exploration applications. Geochemical, isotopic and redox measurements of a suite of groundwaters sampled from around the ABM zone of the Kudz Ze Kayah (KZK) volcanogenic massive sulfide (VMS) deposit in the Yukon, Canada are presented and contrasted with other case studies from a variety of mineral deposit types. This deposit has atypically high As (up to 4.3 wt%, average 2457 ppm) and Se (up to 2620 ppm, average 157 ppm) contents in the sulfide mineralization. As a relatively undisturbed deposit (unmined), it is an ideal site to study the mobility and solubility of trace metals in groundwaters. Herein we present field measurements (pH, dissolved oxygen, specific conductance, oxidation–reduction potential and temperature), major ion, trace element, anion (Cl, Br, SO4, PO4), and stable isotope (δ2H, δ13CDIC, δ18O, δ18OSO4, δ34S) data.Waters are dominantly low-salinity HCO3 to HCO3–SO4-type waters with variable sulfate (4.83 to 601 mg l−1), Ca (23–235 mg l−1) Mg (3.1–96.8 mg l−1), Na (0.30–66.9 mg l−1) and K (0.55 to 6.25 mg l−1) concentrations. These waters also have variable trace element concentrations that include As (0.01 to 148 µg l–1), Se (<0.02 to 1.01 µg l–1), Fe (0.01 to 3.84 mg l−1), Zn (<0.2 to 1070 µg l–1), Pb (<0.01 to 8.4 µg l–1), Cu (0.03 and 24.5 µg l–1) and Sb (0.01 to 54.4 µg l–1). Some waters also have elevated concentrations (compared to most meteoric waters) of Nb (up to 0.3 µg l–1), Y (up to 1.42 µg l–1), Zr (up to 18 µg l–1), and the rare-earth elements (REEs) (ΣREE up to 2.04 µg l–1). The δ18O (−22.8 to −20.9 ‰) and δ2H (−174 to −158 ‰), together with the δ13CDIC (−10.6 to +1.9 ‰), δ34S (+10 to +12 ‰) and δ18OSO4 (15.5 to −4.75 ‰) all suggest that local meteoric water has interacted with massive sulfide mineralization at the ABM zone. Our results demonstrate the requirement for the use of multiple techniques in hydrogeochemical studies, with dissolved concentrations of major and trace elements coupled with a suite of stable isotopes that help define a larger geochemical footprint for the KZK deposit. Water–mineral interaction between groundwater aquifers and VMS deposits like the ABM zone are distinctly different from dispersion halos described from other deposit types (i.e. Cu porphyry, unconformity U).Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
  PubDate: Thu, 03 Mar 2022 00:00:00 GMT
Quantitative prediction of prospectivity for Pb–Zn deposits in Guangxi
(China) by back-propagation neural network and fuzzy weights-of-evidence
modelling
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  Authors: Xie S; Huang N, Deng J, et al.
  Abstract: One significant geochemical data processing aim is to delineate anomalies associated with mineral deposits. In areas with strong surface weathering, the accumulation centres of surface geochemical anomalies are often not completely matched with locations of mineral deposits. This affects anomaly interpretation and mineral prospectivity prediction. In order to solve this challenging problem, quantitative prediction of mineral prospectivity based on multi-information fusion techniques has been one of the research hotspots in the field of data analysis in recent years. This study first summarized the geological background and metallogenic control factors of each tectonic unit in Guangxi, and then analysed the relationship between Pb–Zn deposits and Pb–Zn geochemical anomalies from 60 767 geochemical stream sediment samples. Based on the re-classified geochemical element contents, gravity, aeromagnetic data and fault, magmatic rock, magmatic rock and fault intersection buffer data as input layers, together with 302 Pb–Zn ore occurrences selected as training data sets, quantitative prediction of prospectivity for Pb–Zn ore deposits in the study area was carried out using back-propagation neural network and fuzzy weights-of-evidence methods. It was found that the Pb–Zn mineral prospectivity prediction areas based on multi-information fusion techniques can eliminate effectively the influence of secondary accumulation of elements during weathering of carbonate rocks on the recognition of deposit-associated stream sediment geochemical anomalies, and identify effectively the mineral resources closely related to rock mass and structure distribution. These analyses reveal the metallogenic regularity of Pb–Zn deposits from the perspective of data mining based on machine learning and geographical information system multi-information fusion for delineation of prospective metallogenic target areas. The purpose here was to provide new ideas for reducing the effects of secondary weathering of extensive carbonate rocks in Guangxi, and in other regions with similar landscapes, on mineral prospectivity prediction.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
  PubDate: Thu, 03 Mar 2022 00:00:00 GMT
Removal of Mn 2+ in geothermal water by manganese sand: process and
mechanisms
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  Authors: Feng W; Wu J, Lu J.
  Abstract: Geothermal water resources are being exploited widely in many areas to relieve pressure on water resources generally. Excessive Mn2+ concentration in geothermal water will seriously reduce its utilization rate. Therefore, this study investigated the removal of Mn2+ from simulated geothermal water by manganese sand. The Mn2+ removal rate from simulated water with a concentration of 10 mg l−1 by 2 g manganese sand at 298, 323, 343 and 363 K was more than 90%. The removal efficiency of Mn2+ is influenced by adsorbent dosage, adsorbent particle size, initial Mn2+ concentration and competing ions, and less so by a pH of 5–9. A pseudo-first-order kinetic model fits the adsorption data better than a pseudo-second-order model. The pseudo-first-order adsorption rate constants (K1) ranged from 0.14 to 0.5 h−1 as the temperature increased from 298 to 363 K. The Langmuir isotherm model fits the adsorption data better than the Freundlich and Temkin isotherm models. The maximum monolayer adsorption capacities (qm) obtained by the Langmuir isotherm model fitting were 0.91/1.02/1.22/1.23 mg g–1 at 298/323/343/363 K. Thermodynamic studies revealed that the adsorption was endothermic and physical in nature. These findings suggest that the potential of manganese sand for removing Mn2+ in geothermal water is considerable.Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
  PubDate: Mon, 28 Feb 2022 00:00:00 GMT
John Somerville Tooms (1927–2021)
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  PubDate: Mon, 21 Feb 2022 00:00:00 GMT
Hydrogeochemistry of porphyry-related solutes in ground and surface
waters; an example from the Casino Cu–Au–Mo deposit, Yukon, Canada
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  Authors: Kidder JA; McClenaghan MB, Leybourne MI, et al.
  Abstract: The Casino Cu–Au–Mo deposit is one of the largest and highest-grade porphyries of its kind in Canada, residing in an unglaciated region of west-central Yukon. A batch of 22 stream water samples and eight groundwater samples were collected proximal to the deposit for the purpose of identifying the most diagnostic trace element and isotopic pathfinders associated with the hydrothermal mineralization, as well as establishing natural hydrogeochemical baselines for the area. Water chemistry around this deposit was investigated because: (i) the deposit has not yet been disturbed by mining; (ii) the deposit was known to have metal-rich waters in local streams; and (iii) the deposit has atypically preserved ore zones. Surface and ground waters around the Casino deposit are anomalous with respect to Cd (up to 5.4 µg l–1), Co (up to 64 µg l–1), Cu (up to 1657 µg l–1), Mo (up to 25 µg l–1), As (up to 17 µg l–1), Re (up to 0.7 µg l–1) and Zn (up to 354 µg l–1) concentrations. Sulfur and Sr isotopes are consistent with proximal waters interacting with the Casino rocks and mineralization; a sulfide-rich bedrock sample from the deposit has δ34S = −1.2‰ and proximal groundwaters are only slightly heavier (−0.3 to 3.1‰). These geochemical and isotopic results indicate interaction and dispersion of porphyry-related solutes in ground and surface waters and point to the suitability of hydrogeochemistry as a medium for mineral exploration for porphyry-style mineralization in the Yukon, and elsewhere in Canada.Supplementary material: Dissolved concentration data for major and trace elements for the ground and stream water samples from Casino are available at https://doi.org/10.6084/m9.figshare.c.5778911Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
  PubDate: Mon, 21 Feb 2022 00:00:00 GMT