Pub Date : 2024-11-16DOI: 10.1016/j.oreoa.2024.100075
Wenneng Zhao , Mingshi Feng , Yanyu Gao , Ying Fu , Wanbin Meng , Siyuan Fan , Yi Lan , Bing Zhang
Several methods, such as field-emission environmental scanning electron microscope (FE-SEM), low-temperature nitrogen adsorption-desorption, high-pressure mercury injection tests, focused ion beam scanning electron microscope (FIB-SEM), and high-magnification and large-scale quantitative analytical methods involving argon ion polishing-FE-SEM, have been carried out on lacustrine fine-grained mixed sedimentary reservoirs of the upper fourth-lower third members of the Shahejie Formation in the Jiyang Depression, with the aim of clarifying their microstructural characteristics. Five types of reservoir spaces of fine-grained mixed sedimentary reservoirs were recognized in this study, including intergranular, dissolution, intercrystalline and intracrystalline pores, and fractures. The favorable reservoir spaces are pores with diameters ranging from 40 nm to 300 nm, which are dominated by intergranular pores, grain edge seams, and dissolution pores. The high-pressure mercury injection curves can be divided into three types. Types I and II, with good pore structures, occur mainly in mudstone and dolomite facies, whereas type III, with poor pore structures, is present in limestone facies. The low-temperature nitrogen adsorption-desorption showed that the adsorption volume of dolomite facies is the highest, and the pore morphologies are plate-like. The adsorption amount of mudstone facies is higher than limestone facies, and the pore morphologies are dominated by ink bottle-shaped and parallel plate-like. FIB-SEM analyses reveal that the samples display moderate connectivity. These findings suggest that the different types of lithologic reservoirs of fine-grained mixed sedimentary rocks in the Jiyang Depression have different microstructures, with the argillaceous dolomite, calcareous mudstone, calciferous mudstone, and argillaceous limestone changing gradually from good to poor.
{"title":"Comprehensive characterization of micro-pore structures in different lithologies of the lacustrine fine-grained mixed sedimentary reservoir of the Shahejie Formation in the Jiyang Depression","authors":"Wenneng Zhao , Mingshi Feng , Yanyu Gao , Ying Fu , Wanbin Meng , Siyuan Fan , Yi Lan , Bing Zhang","doi":"10.1016/j.oreoa.2024.100075","DOIUrl":"10.1016/j.oreoa.2024.100075","url":null,"abstract":"<div><div>Several methods, such as field-emission environmental scanning electron microscope (FE-SEM), low-temperature nitrogen adsorption-desorption, high-pressure mercury injection tests, focused ion beam scanning electron microscope (FIB-SEM), and high-magnification and large-scale quantitative analytical methods involving argon ion polishing-FE-SEM, have been carried out on lacustrine fine-grained mixed sedimentary reservoirs of the upper fourth-lower third members of the Shahejie Formation in the Jiyang Depression, with the aim of clarifying their microstructural characteristics. Five types of reservoir spaces of fine-grained mixed sedimentary reservoirs were recognized in this study, including intergranular, dissolution, intercrystalline and intracrystalline pores, and fractures. The favorable reservoir spaces are pores with diameters ranging from 40 nm to 300 nm, which are dominated by intergranular pores, grain edge seams, and dissolution pores. The high-pressure mercury injection curves can be divided into three types. Types I and II, with good pore structures, occur mainly in mudstone and dolomite facies, whereas type III, with poor pore structures, is present in limestone facies. The low-temperature nitrogen adsorption-desorption showed that the adsorption volume of dolomite facies is the highest, and the pore morphologies are plate-like. The adsorption amount of mudstone facies is higher than limestone facies, and the pore morphologies are dominated by ink bottle-shaped and parallel plate-like. FIB-SEM analyses reveal that the samples display moderate connectivity. These findings suggest that the different types of lithologic reservoirs of fine-grained mixed sedimentary rocks in the Jiyang Depression have different microstructures, with the argillaceous dolomite, calcareous mudstone, calciferous mudstone, and argillaceous limestone changing gradually from good to poor.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"18 ","pages":"Article 100075"},"PeriodicalIF":0.0,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143096556","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}
Pub Date : 2024-10-01DOI: 10.1016/j.oreoa.2023.100037
Precision in uncovering the seismic source mechanism and conducting a thorough monitoring of deformation characteristics resulting from surface rupture is of paramount importance for geological comprehension, disaster management, and emergency response. This study employs both ascending and descending orbit Sentinel-1 data to capture the horizontal and vertical deformation traits of the Ms6.9 earthquake in Menyuan, Qinghai, on January 8, 2022, consequently exposing its seismogenic structure. The research outcomes suggest: the Menyuan earthquake generated an elliptical deformation zone measuring 30 × 20 km, with the maximum line-of-sight seismic displacement reaching 6.8 cm. And then, the vertical deformation field exhibited a range between -0.28 m and 0.42 m, while the horizontal deformation field ranged from -0.89 m to 0.94 m. This indicates that the earthquake's deformation is primarily oriented in the east-west direction. The left plate exhibited an upward trend with a NWW orientation, while the right plate displayed a downward trend with a SEE orientation, suggesting that the Menyuan earthquake can be classified as a "NWW-SEE" type. Furthermore, the seismic epicenter of this earthquake was predominantly concentrated in the western segment of the Lenglongling Fault. Two powerful earthquakes sequentially struck along this fault zone, intensifying the imperative for seismic geological research in the region. Additionally, this instance can serve as a benchmark for monitoring deformations and elucidating the seismic source mechanism in earthquakes with comparable seismogenic structures.
{"title":"Extract and analysis of surface deformation caused by Mengyuan earthquake in Qinghai using ascending and descending tracks D-InSAR technology","authors":"","doi":"10.1016/j.oreoa.2023.100037","DOIUrl":"10.1016/j.oreoa.2023.100037","url":null,"abstract":"<div><div><span>Precision in uncovering the seismic source mechanism and conducting a thorough monitoring of deformation characteristics resulting from surface rupture is of paramount importance for geological comprehension, disaster management, and emergency response. This study employs both ascending and descending orbit Sentinel-1 data to capture the horizontal and vertical deformation traits of the Ms6.9 earthquake in Menyuan, Qinghai, on January 8, 2022, consequently exposing its seismogenic structure. The research outcomes suggest: the Menyuan earthquake generated an elliptical deformation zone measuring 30 × 20 km, with the maximum line-of-sight seismic displacement reaching 6.8 cm. And then, the vertical deformation field exhibited a range between -0.28 m and 0.42 m, while the horizontal deformation field ranged from -0.89 m to 0.94 m. This indicates that the earthquake's deformation is primarily oriented in the east-west direction. The left plate exhibited an upward trend with a NWW orientation, while the right plate displayed a downward trend with a SEE orientation, suggesting that the Menyuan earthquake can be classified as a \"NWW-SEE\" type. Furthermore, the seismic </span>epicenter of this earthquake was predominantly concentrated in the western segment of the Lenglongling Fault. Two powerful earthquakes sequentially struck along this fault zone, intensifying the imperative for seismic geological research in the region. Additionally, this instance can serve as a benchmark for monitoring deformations and elucidating the seismic source mechanism in earthquakes with comparable seismogenic structures.</div></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100037"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138987100","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}
Pub Date : 2024-10-01DOI: 10.1016/j.oreoa.2023.100036
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.
Radioactive minerals found in the conglomerates comprise leucoxene, brannerite, carbon nodules, monazite, allanite, thorite, and uraninite.
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.
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 234U/238U equilibrium and because of the U depletion in the surface samples, further investigations using α-spectrometry and Pb-isotope analyses were employed.
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.
The estimation of the original pre-weathering U concentration in the surface conglomerates is based on the measured Pb-isotope ratios 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb 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.
{"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":"<div><div>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.</div><div><span><span>Radioactive minerals found in the conglomerates comprise leucoxene, brannerite, carbon nodules, </span>monazite, </span>allanite<span>, thorite, and uraninite.</span></div><div>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.</div><div><span>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 </span><sup>234</sup>U/<sup>238</sup>U equilibrium and because of the U depletion in the surface samples, further investigations using α-spectrometry and Pb-isotope analyses were employed.</div><div>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.</div><div>The estimation of the original pre-weathering U concentration in the surface conglomerates is based on the measured Pb-isotope ratios <sup>206</sup>Pb/<sup>204</sup>Pb, <sup>207</sup>Pb/<sup>204</sup>Pb, and <sup>208</sup>Pb/<sup>204</sup>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.</div><div>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}
Existing algorithms for estimating the maturity of lunar soils are not optimized for data from any of the orbital sensors which are currently active. This paper addresses this issue by proposing an algorithm for estimating soil maturity (IS/FeO) using spectroscopic data at the spectral resolution of the Moon Mineralogy Mapper (M3). As part of this method, four key spectral parameters for estimating IS/FeO are identified and used to train a Support Vector Regression (SVR) model. The physical significance of each parameter is discussed, and the equation of the predictive hyperplane is provided for increased transparency. The proposed method outperforms state-of-the-art algorithms and returns a coefficient of determination (R2) of 0.92 over the Lunar Soil Characterization Consortium (LSCC) dataset.
{"title":"Feature Engineering for estimating the maturity of lunar soils from spectroscopic data","authors":"Sandeepan Dhoundiyal , Shivam Kumar , Debosmita Paul , Malcolm Aranha , Guneshwar Thangjam , Alok Porwal","doi":"10.1016/j.oreoa.2024.100064","DOIUrl":"10.1016/j.oreoa.2024.100064","url":null,"abstract":"<div><p>Existing algorithms for estimating the maturity of lunar soils are not optimized for data from any of the orbital sensors which are currently active. This paper addresses this issue by proposing an algorithm for estimating soil maturity (I<sub>S</sub>/FeO) using spectroscopic data at the spectral resolution of the Moon Mineralogy Mapper (M<sup>3</sup>). As part of this method, four key spectral parameters for estimating I<sub>S</sub>/FeO are identified and used to train a Support Vector Regression (SVR) model. The physical significance of each parameter is discussed, and the equation of the predictive hyperplane is provided for increased transparency. The proposed method outperforms state-of-the-art algorithms and returns a coefficient of determination (<em>R</em><sup><em>2</em></sup>) of 0.92 over the Lunar Soil Characterization Consortium (LSCC) dataset.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100064"},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142239307","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}
Pub Date : 2024-09-11DOI: 10.1016/j.oreoa.2024.100067
Fonabe Victor Embui , Mbafor Phebe Ursula Teh , Ngambu Aloysius Afahnwie , Cyriel-Armand-Michel Maurille Moudioh
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 > 20, and Th/Nb > 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<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 <0.3 values revealing elevated magma water content while Dy/Yb >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.
锆石矿物可抵御结晶后的蚀变，并可存储结晶后的化学元素信息，这使其成为地球科学领域一个具有多种应用的潜在工具。这些应用包括通过锆石中的 Hf-同位素对熔体和流体源进行示踪，利用 Eu 和 Ce 对岩浆的氧化还原状态进行评估，以及分馏结晶程度，这可以提供与矿石类型、矿化和源岩有关的宝贵信息。本综述利用喀麦隆东部金矿区已发表的岩浆锆石数据（痕量元素和稀土元素），确定了花岗岩侵入体成岩时熔体来源的区域趋势、氧化还原状态以及熔体批次的含水量。喀麦隆东部金矿区位于阿达马瓦-雅温得域内，该域是更大的中非金矿带的一部分，其特征是泛非时代的花岗岩侵入体，推测该金矿带沿线的金矿化就位于该侵入体中。锆石痕量比（Nb/Yb ≥ 0.01，Yb/U ≥ 0.1，U/Nb > 20，Th/Nb > 10）将所研究的锆石归类于大陆领域，这阐明了主要的地壳熔体来源，并设想在某些地方有地幔输入。数据还显示出 176Hf/177Hf (ƐHf<0)的低值特征，这也支持了熔体的主要地壳来源。此外，该地区的 K、Rb、Th、Y 和 Nb 浓度以及 Sr 和 Nd 同位素特征都很高，说明较古老的地壳岩石在低压下熔化。鉴于广泛报道的金矿起源与上述熔体形成的花岗岩侵入体之间的遗传联系，本研究还评估了熔体的氧化还原状态和含水量代用指标，这些指标被认为对金矿化有重大影响。锆石颗粒中的 Eu/Eu* 值从 0.02 到 1.6 不等，Ce/Nd 比值从 0.28 到 181.67 不等，说明了还原熔体到氧化熔体的特征。参照 Lu 等人（2016 年）所报告的肥沃和贫瘠岩组，所审查的数据位于肥沃和贫瘠区域内，以肥沃侵入体为主。Dy/Yb 数据位于 Dy/Yb = 0.3 的判别线上下，<0.3 值显示岩浆含水量升高，而 Dy/Yb >0.3 是无水熔体的临界值。研究得出结论，熔体的主要来源是较古老地壳岩石的再加工，以及零星的地幔输入。参与这些侵入体成岩过程的熔体批次在还原组和氧化组之间波动，氧化组和岩浆水含量的升高有助于金矿化。
{"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 , Mbafor Phebe Ursula Teh , Ngambu Aloysius Afahnwie , 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 > 20, and Th/Nb > 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 <sup>176</sup>Hf/<sup>177</sup>Hf (ƐHf<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 <0.3 values revealing elevated magma water content while Dy/Yb >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":"2024-09-11","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}
Pub Date : 2024-08-31DOI: 10.1016/j.oreoa.2024.100066
Mingwei Song , Yiwei Peng , Youliang Chen , Yan Zhang , Hong Yang , Shipu Xu , Qi wang
Research on fluid inclusions in Iron Oxide Copper Gold hydrothermal systems has significantly progressed over the past few decades. This paper summarizes the major research advances including petrography, microthermometry, and the compositional of fluid inclusions, as well as the main theories regarding the origins and evolution of ore formation. Fluid inclusions are prevalent within hydrothermal minerals of IOCG systems, including aqueous biphasic (L-V), three-phase (L-V-S) and multiphase (L-V-nS), aqueous-carbonic (LH2O-LCO2) and aqueous-carbonic with solids (LH2O-LCO2-S), single phase (LCO2) inclusions. The types and quantity of fluid inclusions are varied in different hydrothermal alteration and mineralization stages. Geochemical investigations have identified at least two distinct fluid contributors in IOCG systems: a hot, saline magmatic-hydrothermal fluid and an external, non-magmatic fluid (e.g., basin brine, meteoric water, formation water, or metamorphic fluids). It is generally believed that the early stages of the hydrothermal alteration are primarily controlled by magmatic fluids rich in metals and volatiles, with the Fe (-REE) mineralization. Non-magmatic fluids mixing at the last stage can effectively induce a temperature decrease or added reduced sulfur may be a significant factor contributing to Cu-Au precipitation.
{"title":"Research progress of fluid inclusions and its application in iron oxide copper-gold (IOCG) deposits","authors":"Mingwei Song , Yiwei Peng , Youliang Chen , Yan Zhang , Hong Yang , Shipu Xu , Qi wang","doi":"10.1016/j.oreoa.2024.100066","DOIUrl":"10.1016/j.oreoa.2024.100066","url":null,"abstract":"<div><p>Research on fluid inclusions in Iron Oxide Copper Gold hydrothermal systems has significantly progressed over the past few decades. This paper summarizes the major research advances including petrography, microthermometry, and the compositional of fluid inclusions, as well as the main theories regarding the origins and evolution of ore formation. Fluid inclusions are prevalent within hydrothermal minerals of IOCG systems, including aqueous biphasic (L-V), three-phase (L-V-S) and multiphase (L-V-nS), aqueous-carbonic (L<sub>H2O</sub>-L<sub>CO2</sub>) and aqueous-carbonic with solids (L<sub>H2O</sub>-L<sub>CO2</sub>-S), single phase (L<sub>CO2</sub>) inclusions. The types and quantity of fluid inclusions are varied in different hydrothermal alteration and mineralization stages. Geochemical investigations have identified at least two distinct fluid contributors in IOCG systems: a hot, saline magmatic-hydrothermal fluid and an external, non-magmatic fluid (e.g., basin brine, meteoric water, formation water, or metamorphic fluids). It is generally believed that the early stages of the hydrothermal alteration are primarily controlled by magmatic fluids rich in metals and volatiles, with the Fe (-REE) mineralization. Non-magmatic fluids mixing at the last stage can effectively induce a temperature decrease or added reduced sulfur may be a significant factor contributing to Cu-Au precipitation.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100066"},"PeriodicalIF":0.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666261224000282/pdfft?md5=0f01760f5ab6e1a6b875afe4356cd6cb&pid=1-s2.0-S2666261224000282-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142168981","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}
Pub Date : 2024-08-27DOI: 10.1016/j.oreoa.2024.100063
Qian Pang , Hao Song , Zhengqi Xu , Shenglin Xu , Guang Hu , Yidong Liu , Jiayu Zhang
Black shale serve as a new uranium sources and provide reducing agents for uranium deposits through hydrocarbon generation. However, the systematically interplay between the black shale and the formation of uranium deposits is not obscure. This paper provides a comprehensive summary and critical assessment of the depositional control factors of uranium in black shales, the extent of uranium migration during hydrocarbon generation, the enrichment of uranium in oil/gas reservoirs, and the relationship between crude oil-natural gas leakage and uranium. The study show that U-riched constituents within black shale persist through mechanisms of adsorption, reduction, complexation, and absorption within matrices rich in phosphates, iron, carbonate minerals, and organic matter. The U in black shale originates from continental weathering, volcanic eruptions, and seabed hydrothermal activities. The average U concentration in black shale is determined by the U content in atmosphere, while its relative content is controlled by the degree of anoxia during the geological historical periods.. Black shale prior to the Late Neoproterozoic period exhibits minimal migration with hydrocarbon substances, whereas black shale post the Late Neoproterozoic period demonstrates migration, with a migration rate ranging approximately between 55 and 75 %. However, the migrated uranium does not accumulate in (ancient) reservoirs. The correlation between hydrocarbon substances and sandstone-type uranium deposit is attributed to the oxygen uptake by hydrocarbons or the thermochemical sulfate reduction (TSR). The study has fundamental significance for further understand the interaction mechanisms between uranium and hydrocarbon substances.
{"title":"Uranium mobility and enrichment during hydrocarbon generation and accumulation processes: A review","authors":"Qian Pang , Hao Song , Zhengqi Xu , Shenglin Xu , Guang Hu , Yidong Liu , Jiayu Zhang","doi":"10.1016/j.oreoa.2024.100063","DOIUrl":"10.1016/j.oreoa.2024.100063","url":null,"abstract":"<div><p>Black shale serve as a new uranium sources and provide reducing agents for uranium deposits through hydrocarbon generation. However, the systematically interplay between the black shale and the formation of uranium deposits is not obscure. This paper provides a comprehensive summary and critical assessment of the depositional control factors of uranium in black shales, the extent of uranium migration during hydrocarbon generation, the enrichment of uranium in oil/gas reservoirs, and the relationship between crude oil-natural gas leakage and uranium. The study show that U-riched constituents within black shale persist through mechanisms of adsorption, reduction, complexation, and absorption within matrices rich in phosphates, iron, carbonate minerals, and organic matter. The U in black shale originates from continental weathering, volcanic eruptions, and seabed hydrothermal activities. The average U concentration in black shale is determined by the U content in atmosphere, while its relative content is controlled by the degree of anoxia during the geological historical periods.. Black shale prior to the Late Neoproterozoic period exhibits minimal migration with hydrocarbon substances, whereas black shale post the Late Neoproterozoic period demonstrates migration, with a migration rate ranging approximately between 55 and 75 %. However, the migrated uranium does not accumulate in (ancient) reservoirs. The correlation between hydrocarbon substances and sandstone-type uranium deposit is attributed to the oxygen uptake by hydrocarbons or the thermochemical sulfate reduction (TSR). The study has fundamental significance for further understand the interaction mechanisms between uranium and hydrocarbon substances.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100063"},"PeriodicalIF":0.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666261224000257/pdfft?md5=f34df12482c5248d9eba3b89962942ad&pid=1-s2.0-S2666261224000257-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142135803","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}
Pub Date : 2024-08-27DOI: 10.1016/j.oreoa.2024.100065
Sidique Gawusu , Benatus Norbert Mvile , Mahamuda Abu , John Desderius Kalimenze
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.
{"title":"Machine learning based prospect targeting: A case of gold occurrence in central parts of Tanzania, East Africa","authors":"Sidique Gawusu , Benatus Norbert Mvile , Mahamuda Abu , 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":"2024-08-27","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}
Drilled well data and 3D seismic data are integrated to model the seal capacity of the Late Campanian- Maastrichtian mudstone in the exploration Block 52 operated by PETRONAS Suriname Exploration & Production BV. The study proposes simple relationships between interval velocity and porosity, porosity against permeability, and normal compaction of the mudstone with depth, based on the drilled well data. The most likely model of the top seal capacity suggests a maximum column height to be in the range of 330 – 350 m in the study area for gas. The model also suggests a gradual increase in the top seal risk towards the northeastern direction of the study area which may be due to the effect of sediment fairway from the nearby Demerara High. On the other hand, an increasing trend of top seal capacity towards the southwestern side of the block relates to the possible effect of the thicker deposition of transgressive fine-grained package with more compaction resulting in a decreasing trend of porosity and permeability of the mudstone.
{"title":"Evaluation of top seal capacity by pseudo-capillary pressure model in Suriname offshore Basin","authors":"Sumangal Dasgupta, Mariah Harris, Zurriya Hayati Bt Hasnan, Ritchie Martua Simamora","doi":"10.1016/j.oreoa.2024.100061","DOIUrl":"10.1016/j.oreoa.2024.100061","url":null,"abstract":"<div><p>Drilled well data and 3D seismic data are integrated to model the seal capacity of the Late Campanian- Maastrichtian mudstone in the exploration Block 52 operated by PETRONAS Suriname Exploration & Production BV. The study proposes simple relationships between interval velocity and porosity, porosity against permeability, and normal compaction of the mudstone with depth, based on the drilled well data. The most likely model of the top seal capacity suggests a maximum column height to be in the range of 330 – 350 m in the study area for gas. The model also suggests a gradual increase in the top seal risk towards the northeastern direction of the study area which may be due to the effect of sediment fairway from the nearby Demerara High. On the other hand, an increasing trend of top seal capacity towards the southwestern side of the block relates to the possible effect of the thicker deposition of transgressive fine-grained package with more compaction resulting in a decreasing trend of porosity and permeability of the mudstone.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100061"},"PeriodicalIF":0.0,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142002282","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}
Pub Date : 2024-08-12DOI: 10.1016/j.oreoa.2024.100062
Sukun Zhang , Cuihua Chen , Junqiang Xu , Xing Jin , Hui Wang , Shaoping Feng , Xinhui Liang
1. Three-dimensional (3D) deterministic modeling is crucial for analyzing the controlling factors of mineralization. The Shanggong gold deposit, situated in the southern margin of North China Craton, represents a magmatic hydrothermal deposit. To construct the 3D deterministic model, boreholes, cross-sections, and geochemistry assays are integrated based on the geological characteristics of the Shanggong gold deposit. This paper summarizes its contents as follows: 1) GoCAD software can be utilized to build a 3D geology model encompassing faults and ore bodies; 2) Geostatistics and discrete smooth interpolation (DSI) can be employed to create a 3D attribute model involving grade and Au/Pb ratio. The findings reveal that: 1) High-value zones are associated with NE and NNE trending cross faults; 2) Deterministic modeling, such as grade model and Au/Pb ratio model, effectively elucidates the metallogenic process mechanism.
1.三维（3D）确定性建模对于分析成矿控制因素至关重要。上宫金矿床位于华北克拉通南缘，是一个岩浆热液矿床。为了构建三维确定性模型，根据上宫金矿床的地质特征，对钻孔、横断面和地球化学化验进行了整合。本文内容概述如下：1）利用 GoCAD 软件建立包括断层和矿体在内的三维地质模型；2）利用地质统计学和离散平滑插值法（DSI）建立涉及品位和金/铅比（Au/Pb ratio）的三维属性模型。研究结果表明1）高价值区与 NE 和 NNE 走向的交叉断层有关；2）品位模型和 Au/Pb 比率模型等确定性模型可有效阐明成矿过程机制。
{"title":"Deterministic modelling for driving factors of mineralization in Shanggong gold deposit (China)","authors":"Sukun Zhang , Cuihua Chen , Junqiang Xu , Xing Jin , Hui Wang , Shaoping Feng , Xinhui Liang","doi":"10.1016/j.oreoa.2024.100062","DOIUrl":"10.1016/j.oreoa.2024.100062","url":null,"abstract":"<div><p>1. Three-dimensional (3D) deterministic modeling is crucial for analyzing the controlling factors of mineralization. The Shanggong gold deposit, situated in the southern margin of North China Craton, represents a magmatic hydrothermal deposit. To construct the 3D deterministic model, boreholes, cross-sections, and geochemistry assays are integrated based on the geological characteristics of the Shanggong gold deposit. This paper summarizes its contents as follows: 1) GoCAD software can be utilized to build a 3D geology model encompassing faults and ore bodies; 2) Geostatistics and discrete smooth interpolation (DSI) can be employed to create a 3D attribute model involving grade and Au/Pb ratio. The findings reveal that: 1) High-value zones are associated with NE and NNE trending cross faults; 2) Deterministic modeling, such as grade model and Au/Pb ratio model, effectively elucidates the metallogenic process mechanism.</p></div>","PeriodicalId":100993,"journal":{"name":"Ore and Energy Resource Geology","volume":"17 ","pages":"Article 100062"},"PeriodicalIF":0.0,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666261224000245/pdfft?md5=1465319e95d95f73a05dd4797a504af9&pid=1-s2.0-S2666261224000245-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142006350","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}
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