Ore and Energy Resource Geology最新文献

{"title":"Ore-forming process of the Xiaoyuzan gold deposit in the Western Tianshan, Northwest China: Constraints from mineralogy and S isotopes of sulfides","authors":"Yan Zhang ,&nbsp;Yiwei Peng ,&nbsp;Xuexiang Gu ,&nbsp;Qi Wang ,&nbsp;Mingwei Song","doi":"10.1016/j.oreoa.2024.100058","DOIUrl":"https://doi.org/10.1016/j.oreoa.2024.100058","url":null,"abstract":"<div><p>The Xiaoyuzan deposit is a typical intermediate-sulfidation epithermal Au deposit in the Boluokenu metallogenetic belt. The orebodies are hosted by the Lower Carboniferous Dahalajunshan Formation volcanic rocks and controlled by the NW- and NNW-striking faults. The metal minerals present in the ores mainly include pyrite, sphalerite, galena, chalcopyrite, and tetrahedrite. The non-metallic minerals are primarily composed of quartz, calcite, and sericite. Three ore-forming stages are distinguished based on mineral assemblages, wall-rock alteration, and vein crosscutting relationships, including the quartz-pyrite stage (I) with silicification and propylitization, quartz-sulfide stage (II) with phyllic alteration, and quartz-carbonate stage (Ⅲ) with carbonatization. Three different types of pyrite are classified: coarse-grained PyI with cubic from the wall rock, fine-grained PyII with a crystal form of pentagonal dodecahedron in the quartz-sulfide veins, and coarse-grained cubic PyⅢ in the quartz-carbonate veins. The <em>in-situ</em> δ³⁴S value range of sulfides from stage I, stage II and stage Ⅲ are 5.0 ‰ to 5.5 ‰, 4.3 ‰ to 6.5 ‰ and 5.7 ‰ to 6.2 ‰, respectively. The composition of S isotopes indicates that the source of the sulfur is magmatic in origin, with main contribution from the host rock. All the types of pyrite are relatively enriched with Sb, Cu, Ag, Pb, Bi, and As. The composition of pyrite suggests that the Au in the pyrite present as lattice gold (Au⁺¹). The gradual decrease in Co contents from in PyⅠ, PyⅡ to PyⅢ indicates a gradual decrease in temperature during fluid evolution. The contents of trace elements in sphalerite are relatively low, with Fe, Mn, Cd, and Cu being relatively enriched. Using the sphalerite geothermometer (GGIMFis), the calculated temperature falls within the range of 303.0 to 334.3 °C. Pyrite II is characterized by the occurrence of oscillatory zones, suggesting rhythmic changes in fluid physicochemical conditions and compositions. Although coexisting of liquid-rich and vapor-rich aqueous inclusions were locally observed in stage II quartz according to previous studies, the absence of crustiform/colloidal/lattice bladed quartz in the main stage suggests that slight or gentle fluid boiling has occurred. In summary, it is proposed that fluid-rock reactions made great contribution for the precipitation of gold and sulfides in the Xiaoyuzan deposit.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100058"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666261224000208/pdfft?md5=527cdac62344c94d706daeb9d58d92bf&pid=1-s2.0-S2666261224000208-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141540814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis of Variscan and Yanshanian magmatic rocks in the Longjiang region of Heilongjiang province and implications for ore exploration","authors":"Jie Zhang ,&nbsp;Shuyi Dong ,&nbsp;Huihui Yong ,&nbsp;Yu Zhao ,&nbsp;Hong Liu ,&nbsp;Xuexing Xie ,&nbsp;Yulang Lu ,&nbsp;Jinchi Li","doi":"10.1016/j.oreoa.2024.100048","DOIUrl":"10.1016/j.oreoa.2024.100048","url":null,"abstract":"<div><p>The Longjiang region is located on the eastern slope of the southern section of the Great Xing'an Range, in the transition zone between the Songliao Basin and Great Xing'an Range uplift. As it is an extension of the Inner Mongolia Linxi-Tuquan Cu-Mo-Pb-Zn metallogenic belt in the Heilongjiang region, it has conditions conducive to the formation of porphyry deposits. We report zircon U-Pb dating and whole-rock geochemistry data of magmatic rocks in representative mineralized points in the Longjiang region. Zircon U-Pb age shows that the age of magmatic rocks is concentrated in the Variscan period (312 ± 5 ∼ 294 ± 2Ma) and Yanshanian period (134 ± 2 ∼ 123 ± 1Ma). According to whole-rock geochemical analysis, the granites have SiO₂ contents of 61.2–69.16 % (66.9 % on average), Al₂O₃ contents of 13.87–15.98 %, MgO contents of 0.6–2.22 %, TiO₂ contents of 0.25–0.88 %, K₂O contents of 2.70–3.63 %, Na₂O/K₂O ratios of 1.05–2.05, and high K₂O+Na₂O contents (5.8–7.17 %), which are consistent with adakitic rocks. Yanshanian granites have A/CNK values of 1.02–2 and an average differentiation index of 84.7, which indicates that they are highly differentiated I-type granites. Variscan I-type granites represent the post-collisional setting of the Paleo-Asian Ocean and are relatively scarce in the region. Yanshanian highly differentiated I-type granites are products of the Paleo-Pacific Ocean's post-collisional retreat and are widely distributed in the region. As the materials and fluids that formed the Liujiushan, Haiyang, and Fendou deposits were derived from magmatic activities, and Variscan and Yanshanian magmas have excellent ore-forming potential. The highly differentiated I-type granites formed by intense Yanshanian magmatism are the most promising candidates for ore exploration in this region.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100048"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140282863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uranium distribution in the promise reefs of the Mesoarchean Westrand Group, Witwatersrand Supergroup, South Africa","authors":"","doi":"10.1016/j.oreoa.2023.100036","DOIUrl":"10.1016/j.oreoa.2023.100036","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Mesoarchean Westrand Group (2932 – 2923 Ma) constitutes the lower portion of the Witwatersrand Supergroup. Compared to the overlying Central Rand Group which is well known for its world-class conglomerate-hosted gold-uranium deposits, the economic potential of palaeoplacers in the Westrand Group has not been fully explored. This study aims to assess the uranium potential of the Promise Reefs in the Westrand Group. Field exposures of the Promise Reefs and boreholes drilled down-dip from the surface outcrops were investigated in the Westrand area. Three reef zones were recognized consisting of well-mineralized, matrix-to clast-supported, small pebble conglomerates with associated medium- to coarse-grained quartzite.&lt;/div&gt;&lt;div&gt;&lt;span&gt;&lt;span&gt;Radioactive minerals found in the conglomerates comprise leucoxene, brannerite, carbon nodules, &lt;/span&gt;monazite, &lt;/span&gt;allanite&lt;span&gt;, thorite, and uraninite.&lt;/span&gt;&lt;/div&gt;&lt;div&gt;Analyses of U and Th from borehole samples reported mean values of 120 ppm for U and 60 ppm for Th. Maximum U and Th concentrations are 630 ppm and 125 ppm, respectively. The highest U/Th ratio was 17.4 with a mean value of 2. The conglomerates from surface outcrops have maximum U and Th concentrations of 111 ppm and 140 ppm, respectively, with a mean U value of 19.5 ppm and a mean Th value of 26.6 ppm, and a mean U/Th ratio of 0.6. Comparison of the data shows that surface outcrops generally report lower U concentrations than their unweathered equivalents.&lt;/div&gt;&lt;div&gt;&lt;span&gt;Also, U assays by γ-spectrometry and INAA of the same samples from surface outcrops yielded inconsistent results. As U exploration by field γ-spectrometry relies on the existence of &lt;/span&gt;&lt;sup&gt;234&lt;/sup&gt;U/&lt;sup&gt;238&lt;/sup&gt;U equilibrium and because of the U depletion in the surface samples, further investigations using α-spectrometry and Pb-isotope analyses were employed.&lt;/div&gt;&lt;div&gt;The results obtained from α-spectrometry point to complex U redistribution processes in the surface conglomerate with several stages of uranium loss and/or gain. The bulk of the U was removed during an early stage of surface exposure and supergene alteration, probably more than 1.4 Ma ago.&lt;/div&gt;&lt;div&gt;The estimation of the original pre-weathering U concentration in the surface conglomerates is based on the measured Pb-isotope ratios &lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb, &lt;sup&gt;207&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb, and &lt;sup&gt;208&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb and the Pb and Th concentrations. The data were inserted into U-Th-Pb age equations which were reformulated and solved for the U concentrations. To test the method, for a suite of borehole samples the same treatment was applied. The calculated fresh-rock U tenor indicates the occurrence of supergene uranium losses which are of the same magnitude as the U losses caused by experimental leaching of fresh conglomerate samples. The high amount of radiogenic Pb found in the surface samples points to severe uranium losses earlier than 100 Ma ago.&lt;/div&gt;&lt;div&gt;The","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100036"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138992767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A review of granite melt source, and associated gold fertility potential in Batouri, Betare Oya, Meiganga, and Ngazi-Tina gold districts in the eastern goldfield of Cameroon: Insight from zircon chemistry","authors":"Fonabe Victor Embui ,&nbsp;Mbafor Phebe Ursula Teh ,&nbsp;Ngambu Aloysius Afahnwie ,&nbsp;Cyriel-Armand-Michel Maurille Moudioh","doi":"10.1016/j.oreoa.2024.100067","DOIUrl":"10.1016/j.oreoa.2024.100067","url":null,"abstract":"<div><div>Zircon mineral can resist post-crystallization alteration and store information relating to chemical elements since crystallization time which makes it a potential tool with variable applications in geoscience. These applications include melt and fluid sources tracer through Hf-isotopes in zircon, the evaluation of redox state of magma using Eu and Ce, as well as the degree of fractional crystallization which can give valuable information relating to ore type, mineralization, and the source rock. This review uses magmatic zircon data (trace and rare earth elements) from published works in the eastern goldfield of Cameroon, to establish the regional trend of the melt source, redox state, and water content of the melt batches at the time of emplacement of the granitic intrusions. The eastern goldfield of Cameroon is situated within the Adamawa-Yaoundé Domain, which forms part of the larger Central African Gold Belt, characterized by granitic intrusions of Pan-African age and presumed to host the gold mineralization along this belt. Zircon trace ratios (Nb/Yb ≥ 0.01, Yb/U ≥ 0.1, U/Nb &gt; 20, and Th/Nb &gt; 10) classify the studied zircons within the continental field which elucidates a predominant crustal melt source with mantle input envisaged in places. The data also show characteristic low values of ¹⁷⁶Hf/¹⁷⁷Hf (ƐHf&lt;0) which also support the dominant crustal source of the melt. Moreover, concentrations of K, Rb, Th, Y and Nb together with Sr and Nd isotopic signatures in the area are high depicting low pressure melting of older crustal rocks. With the widely reported genetic link between gold origin and granitic intrusions that resulted from the above melt, this study also evaluated the redox state and water content proxies of the melt that are believed to have a great impact on gold mineralization. Eu/Eu* values in zircon grains range from 0.02 to 1.6 while Ce/Nd ratios are from 0.28 to181.67, and illustrate features of reduced to oxidized melts. With reference to the fertile and infertile suites reported by Lu et al. (2016), the reviewed data plot within the fertile and infertile fields with a domination of fertile intrusions. Dy/Yb data plot above and below the discriminant line of Dy/Yb = 0.3 with &lt;0.3 values revealing elevated magma water content while Dy/Yb &gt;0.3 are critical of an anhydrous melt. The research concludes that the major melt source was from the reworking of older crustal rocks with sporadic mantle inputs. The melt batches involved in the emplacement of these intrusions fluctuated between reduced and oxidized sets with the oxidized batches together with elevated magma water content aiding the gold mineralization.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100067"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ions release stages of Cu-Pb-Zn mine tailings waste: A column leaching simulation","authors":"Lei Xu ,&nbsp;Liang Tang ,&nbsp;Zeming Shi ,&nbsp;Jingsong Yang ,&nbsp;Kunhao Shi ,&nbsp;Haili Zhang ,&nbsp;Yuting Yuan","doi":"10.1016/j.oreoa.2024.100056","DOIUrl":"https://doi.org/10.1016/j.oreoa.2024.100056","url":null,"abstract":"<div><p>Characterizing the leaching behavior and temporal variability of tailings is conducive to managing and preventing ionic toxicity to indigenous communities and environment. For this purpose, this work selected Cu-Pb-Zn tailings waste from Huili County, Sichuan province in China, as a research case, conducting a 60-day column leaching experiment to simulate the leaching behavior of the tailings. The results reveal that the weathering features of tailings, both salt-based ions and potential toxic elements (PTEs), could be subdivided into the rapid dissolution stage and carbonate dissolution stage. Additionally, acid rain can accelerate the weathering of calcite and dolomite, as well as the leaching of PTEs. The weathering of calcite precedes that of dolomite. A bulk release of PTEs occurs in the early stages, ranging approximately between 10.9 % and 33.6 % in the initial seven days, with As and Zn showing notable significance. Therefore, ecological effects of this abnormality necessitate thorough examination, given that the release of PTEs occurs over an extended and prolonged duration. Acid rain can promote ion desorption and weathering of major minerals, thereby facilitating the leaching of salt-based ions and PTEs. This study emphasizes the early rapid release stage of ions pollution from tailings, providing a preliminary understanding of the environmental impacts that may arise from tailings deposition and acidic rain leaching.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100056"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S266626122400018X/pdfft?md5=bb9a0b50a7794a8046740807ee6facf2&pid=1-s2.0-S266626122400018X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141486372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning based prospect targeting: A case of gold occurrence in central parts of Tanzania, East Africa","authors":"Sidique Gawusu ,&nbsp;Benatus Norbert Mvile ,&nbsp;Mahamuda Abu ,&nbsp;John Desderius Kalimenze","doi":"10.1016/j.oreoa.2024.100065","DOIUrl":"10.1016/j.oreoa.2024.100065","url":null,"abstract":"<div><p>Soil geochemical analyses from central Tanzania reveal significant gold (Au) values, highlighting the potential for further exploration in the region. This study employs ensemble machine learning models—XGBoost-RF, XGBoost-SVM, and XGBoost-ANN—to enhance predictions of Au distribution. Among these, the XGBoost-ANN model showed the highest accuracy during the training phase, achieving a Mean Absolute Percentage Error (MAPE) of 1.275, a Root Mean Square Error (RMSE) of 0.031, an R² of 0.999, and a Pearson Correlation Coefficient (PCC) of 0.999. However, its performance declined in the testing phase with a MAPE of 0.0668 and an RMSE of 0.2491, indicating reduced predictiveness on new data. Spatial analyses using Global and Local Moran's I tests revealed no significant global spatial autocorrelation but identified localized clusters of high and low Au concentrations. Specific areas showed significant spatial dependence, enhancing our understanding of the complex geospatial distribution of Au. These findings support the combined use of predictive modeling and spatial statistical methods to refine mineral exploration strategies, highlighting the value of advanced analytics in identifying promising exploration targets.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100065"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142099670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical and U-Pb isotopic insights into uranium (U) enrichment in the soil around a nuclear fuel element plant, in Southwest China","authors":"Xin Cheng ,&nbsp;Jianing Sun ,&nbsp;Kai Ling ,&nbsp;Keyi Zhong ,&nbsp;Bolin Shao ,&nbsp;Lan Li ,&nbsp;Shanshan Zhao ,&nbsp;Yi Huang ,&nbsp;Hao Song ,&nbsp;Bo Cheng","doi":"10.1016/j.oreoa.2024.100045","DOIUrl":"https://doi.org/10.1016/j.oreoa.2024.100045","url":null,"abstract":"<div><p>To assess the impact of nuclear fuel element processing on uranium(U) in the soil environment, a geochemical survey was conducted. The survey provided data on U concentration, speciation, Th/U ratio, and U and Pb isotopic composition in the soil around a nuclear fuel processing plant in Southwest China, which has been operational since 1965, to reveal the enrichment status and sources of U in the soil. The concentrations of Th and Pb in the soil were also compared. The average U concentration was 1.01-1.43 times that of the local background, and U existed primarily as residual U. The enrichment factor value indicates that U is slightly enriched in the soil. The Th/U ratio was higher than the crustal ratio and the world soil average value, indicating that some of the U in the soil has been lost due to surface runoff. The ²³⁵U/²³⁸U ratio distribution shows that a certain amount of ²³⁵U-enriched particles have sedimentation in the downwind direction of the plant soil, which results in a higher ²³⁵U/²³⁸U ratio in this direction. However, in general, the ²³⁵U/²³⁸U ratios were observed to be typical natural values. The ²⁰⁷Pb/²⁰⁶Pb ratio indicates that the U in the U ore enters the soil during nuclear fuel processing.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"16 ","pages":"Article 100045"},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140113833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of polyphase deformation in the formation of iron deposits and gold mineralization in the paleoproterozoic nyong complex greenstone belt (Southwestern Cameroon)","authors":"Yannick Saturnin Evina Aboula ,&nbsp;Seyed Tohid Nabavi ,&nbsp;Jonas Didero Takodjou Wambo ,&nbsp;Sylvestre Ganno ,&nbsp;Paul-Desiré Ndjigui","doi":"10.1016/j.oreoa.2024.100044","DOIUrl":"https://doi.org/10.1016/j.oreoa.2024.100044","url":null,"abstract":"<div><p>The Toko-Nlonkeng area is situated in the Nyong Complex of the northwestern Congo craton. In this study, airborne geophysical data (radiometric and magnetic) and structural data (outcrops and core samples) were used to investigate the relationship between structural evolution, iron formation (IFs)-hosted iron ore deposits, and gold mineralization in the Paleoproterozoic Nyong complex greenstone belt in southwestern Cameroon. Magnetic and radiometric trends, combined with field data, show general NE-SW, NW-SE, and E-W directions that correlate with the main gold-bearing structures. The study area has undergone four (04) deformation phases relating to polycyclic metamorphic and magmatic events. The D₁ and D₂ phases are the result of progressive ductile and transpressional deformation; D₃ is a brittle-ductile deformation; and D₄ is essentially brittle with various types of fracture networks late to post-orogenic. The D₃ deformation phase is characterized by constrictive deformation with C₃ shears and meso‑ to mega-P₃-folds, and the main stress axes show φσ₂ &gt; φσ₁&gt; φσ₃, reflecting a shearing tectonic regime with a maximum E-W shortening. This polyphase deformation is derived from the Eburnean/Trans-Amazonian deformation related to the collision between the Congo and São Francisco cratons. The main strain in the structural style of the Nyong Complex appears to be transpressive tectonics. This study reveals that iron ore and gold mineralization were mostly found on the hinges of folds and confirms that folding shear zones controlled the iron ore and gold target in the Nyong Complex and Northeast Brazil. The study proposes an approach to optimize future exploration activity based on the integration of the data.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"16 ","pages":"Article 100044"},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140181078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of heavy minerals and stream sediment from Bidjouka area, Nyong Complex south Cameroon: implications for gold mineralization","authors":"Ndema Mbongué Jean-Lavenir ,&nbsp;Christian Diomo Mukete ,&nbsp;Djomo Michel Cedric ,&nbsp;Peter Namange","doi":"10.1016/j.oreoa.2024.100039","DOIUrl":"https://doi.org/10.1016/j.oreoa.2024.100039","url":null,"abstract":"<div><p>The stream sediment geochemistry has a wide application in mineral exploration. In this study, we applied the stream sediment geochemistry to decipher the primary source of gold mineralization, determine the mineralogy of heavy mineral concentrate and also to ascertain the provenance, depositional environment, intensity of weathering as well as determine the tectonic setting. To investigate heavy mineral in stream channel, 20 placer materials from Bidjouka area were assessed by thin plate using polarized microscope. The powder was further characterized by ICP-MS using aqua regia. Results show that placers displayed minerals such as magnetite, zircon and gold. Majors geochemical base metal point out low grade of iron (&lt; 5 wt.%), titanium (&lt; 1.05 wt.%) and alumina (&lt; 0.60 wt.%). The following metallic trace elements used for industrial technology are identified in the samples. It mainly concerns manganese and thorium with content less than 328 and 200 ppm respectively as well as mercury (&lt; 550 ppb). Precious metals are also present in the chemical composition of Bidjouka sediments. The main substances identified is gold with the grade above 2 g/tone, which is an important target in mining exploration. Also the mean value of rare earth elements varying between 1256.6 and 3626.8 ppm are so speculative, with negative and positive Eu and Ce anomaly respectively. Gold is bound with sulfide mineral (Au-Bi), suggesting a sulfidation event during sediments deposition. Factor 4 (Co, Mn, Sc, Au, Bi) refers to the mineralization factor and Co, Mn, Sc, Bi serve as pathfinder of gold. Sediments were deposited under humid, oxic and oxidizing conditions; intermediate intensity of weathering processes of the source rocks had prevailed during deposition, and sediments were rich in plagioclase. These continental sediments have quartzose sedimentary provenance, they were originated from metamorphic sources and were deposited in an active continental margin. The results of this study serve as guide for gold exploration and exploitation in the Bidjouka area.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"16 ","pages":"Article 100039"},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139503797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A local rather than a global oxidation in the early Ediacaran deep ocean: Evidence from the Doushantuo Formation in East Guizhou Province, South China","authors":"Renjie Tao ,&nbsp;Xianguo Lang ,&nbsp;Kun Zhao ,&nbsp;Shengxian Zhu ,&nbsp;Gengchen Li ,&nbsp;Chaochao Xing","doi":"10.1016/j.oreoa.2024.100040","DOIUrl":"https://doi.org/10.1016/j.oreoa.2024.100040","url":null,"abstract":"<div><p>After the end of the Cryogenian Snowball Earth glaciations, the Ediacaran Ocean experienced rapid oxidation and a subsequent increase in marine sulfate concentration. This led to a significant negative excursion in pyrite sulfur isotope values, particularly observed in the Doushantuo Formation of the slope facies in the South China. However, the extent of this oxidation event remains unclear. In order to address this, we carried out geochemical analysis of the Doushantuo Formation in the Cenpiaokou section of the Jiangkou County, Guizhou Province. In the Cenpiaokou section, the pyrite is mainly euhedral-subhedral and framboidal in crystal morphology. The pyrite contents are highest at the base of the Doushantuo Formation and decrease towards the middle and upper parts. Similarly, the proportion of framboidal pyrite also decreases upward, ranging from 93 % at the bottom to 9 % in the upper part of the Doushantuo Formation. Additionally, the sulfur isotope of pyrite (δ³⁴S) shows significant differences compared to other slope facies sections. There is no negative excursion in δ³⁴S at the base of the Doushantuo Formation. The lower part of the Doushantuo Formation exhibits frequent oscillations with generally high δ³⁴S values (+6.6 ‰ ∼ +37.3 ‰), while the upper part shows a decreasing trend. The organic carbon isotope (δ¹³C_org) displays an inverse correlation with δ³⁴S, with stable values in the lower part and gradually heavier values in the upper part. The nitrogen isotopes (δ¹⁵N) range from -1.6 ‰ to +2.1 ‰, suggesting a generally anoxic state with strong nitrogen fixation at the Cenpiaokou section. These findings suggest that the deep ocean oxidation during the early Ediacaran was not a global event, but rather a regional event, with anoxia still dominant overall.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"16 ","pages":"Article 100040"},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666261224000026/pdfft?md5=6f9ead9dfa95d0624b1e4ccd870afd7e&pid=1-s2.0-S2666261224000026-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139727146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}