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| 1 | Structural deformation, metallogenic epoch and genetic mechanism of the Woxi Au-Sb-W deposit, Western Hunan Province, South China显示文摘The remobilization,migration,precipitation,and enrichment of ore-forming elements are closely related to structures.Therefore,detailed regional and ore-field structural analyses are critical for determining the genesis of a mineral deposit.The Jiangnan Orogenic Belt(JOB)is an important gold polymetallic metallogenic belt in South China,which is characterized by multiple periods of gold mineralization in the Paleozoic and Mesozoic.However,the genesis of these gold polymetallic deposits is still not well understood due to a lack of systematic research on the regional geology,ore-controlling structures and metallogenic mechanism.In this study,a detailed structural survey at the surface and in the subsurface tunnels was conducted on the Woxi Au-Sb-W deposit,the genesis of which is relatively controversial among the gold polymetallic deposits in the JOB due to poor structural constraints.In addition,a wolframite U-Pb dating was carried out to further constrain the relationship between structures and mineralization.Based on the results of these studies,together with those from previous studies,it is proposed that the Woxi deposit and surrounding areas likely underwent six periods of regional deformation,which are constrained in time and geodynamic setting.Furthermore,we present a systematic discussion on the roles of ore-controlling structures in the transportation,distribution,and deposition of ore-forming elements and localization of orebodies.According to the wolframite dating results,structural analyses,and previous data,we propose that the Woxi Au-Sb-W deposit was formed in two stages during the Yanshanian:a W(wolframite)-Au mineralization stage at ca.140 Ma and an Au-Sb-W(scheelite)mineralization stage at<130 Ma.These mineralizing events are interpreted to have a tight relationship with tectonic reactivation,and the ore-forming fluids were derived from deep sources,including those of magmatic or metamorphic origins.The Woxi deposit can therefore be classified as an“intracontinental reactivation-type”,and the mineralization is related to lithospheric extension caused by plate retreat,retention,and delamination following the cessation of westward subduction of the Paleo-Pacific Plate beneath the East Asian continent. | Bin LI Deru XU Daoyuan BAI Guoxiang CHI Junfeng DAI Cheng GAO Teng DENG Shaohao ZOU Wen MA Guojian WANG Yuexin LING Guangqian ZENG Yinmin LI | 2022 | Science China Earth Sciences2022，65，12： | 2 |
| 2 | Mass Transfer during Hematitization and Implications for Uranium Mineralization in the Zoujiashan Deposit,Xiangshan Volcanic Basin显示文摘The Zoujiashan uranium deposit in the Xiangshan ore field is the largest volcanic-related uranium deposit in China.Hematite-and fluorite-type ores are the predominant mineralization styles.Hematitization in the Xiangshan ore field is closely associated with uranium mineralization,mainly occurring as hematitized rocks enclosing fluorite-type vein ores developed in pre-ore illitized porphyritic lava.Detailed petrographic and mass balance calculation studies were conducted to evaluate the mechanisms for uranium precipitation and mass transfer during hematitization.Petrographic observations suggest that in the hematitized rocks,orthoclase is more altered than plagioclase,and quartz dissolution is common,whereas in the illitized rocks,pyrite commonly occurs within the altered biotite grains,and chlorite grains are locally found.Mass balance calculations indicate that Na2O and U were gained,K2O,Ca O and Si O2were lost,whereas Fe2O3-t remained more or less constant during hematitization.These observations suggest that the hydrothermal fluids were Na-and U-rich and Ca-K-poor,and the Fe2+used for hematitization was locally derived,most likely from biotite,pyrite and chlorite in the host rocks.The Fe2+is inferred to have played the role of reductant to precipitate uranium,and calculation indicates that oxidation of Fe2+provided by host rocks is sufficient to form ores of economic significance.Consequently,the hematite-type ore is interpreted to be generated by the reaction between oxidized ore fluids and reduced components in host rocks.The development of calcite and pyrite in the fluorite ores suggests that perhaps mixing between the U-rich fluid and another fluid carrying reduced sulfur and carbon may have also contributed to uranium mineralization,in addition to temperature and pressure drop associated with the veining. | Teng Deng Guoxiang Chi Xiongjie Zhang Zenghua Li Deru Xu Shengmiao Li Pengfei Du Pei Shang Shaohao Zou Wanpeng Zhou Ke Xu Hai Yan MaWen Zhengpeng Ding | 2022 | Journal of Earth Science2022，33，2： | 0 |
| 3 | Petrogenesis, oxidation state and volatile content of Dongga tonalite in the Gangdese belt, Xizang: Implication for porphyry Cu mineralization显示文摘The Gangdese belt in Xizang has experienced both Jurassic subduction and Cenozoic continental colli-sion processes,making it a globally renowned region for magmatic rocks and porphyry copper deposits.Numerous Jurassic intrusions have been identified in the belt.Apart from the quartz diorite porphyry in the large Xietongmen deposit,the Cu mineralization potential of other Jurassic intrusions in this belt remains unclear.This study presents zircon U–Pb dating and trace elements,apatite major and trace elements as well as published whole-rock geochemi-cal and isotopic data of the Dongga tonalite in the central part of the Gangdese belt,aiming to reveal the petrogen-esis,oxidation state,volatile content,and Cu mineraliza-tion potential of this intrusion.The Dongga tonalite has a zircon U–Pb age of 179.4±0.9 Ma.It exhibits high whole-rock V/Sc values(8.76–14.6),relatively low apatite CeN/Ce*N ratios(1.04–1.28),elevated zircon(Eu/Eu*)N values(an average of 0.44),high Ce^(4+)/Ce^(3+)values(205–1896),and high∆FMQ values(1.3–3.7),collectively suggesting a high magmatic oxygen fugacity.The Dongga tonalite fea-tures amphibole phenocrysts,relatively high whole-rock Sr/Y ratios(20.3–58.9),and lower zircon Ti temperatures(502–740°C),reflecting a high magmatic water content.Estimation of magmatic sulfur content(0.002–0.024 wt%)based on apatite SO3 contents indicates an enriched magma sulfur content.Combined with previous studies and the col-lected Sr–Nd–Hf isotopes,the Dongga tonalite is derived from juvenile lower crust related with subduction of the Neo-Tethys oceanic slab.When compared with Xietongmen ore-bearing porphyries,the Dongga tonalite exhibits remarkable similarities with the Xietongmen ore-bearing porphyries in terms of magma source,tectonic background,magmatic redox state,and volatile components,which indicates that the Dongga tonalite has a high porphyry Cu mineralization potential,and therefore,provides important guidance for the future mineralization exploration. | Liqiang Zhang Xilian Chen Shaohao Zou Deru Xu Xuena Wang Hua Wang | 2024 | Acta Geochimica2024，43，2： | 0 |
| 4 | Geochronology and zircon geochemistry of auriferous intrusions in the Bumo deposit,Hainan Province,China显示文摘Intrusion-related gold deposits(IRGS)are a lowgrade,large-tonnage exploration target.Recently,auriferous magmatic rocks were found in the Bumo deposit of the Gezhen shear zone in Hainan Province,China.However,the geochronology and geochemical characteristics of the intrusions,as well as the mineralization potential,are still unclear.Field and petrographic work show that the sulfidebearing intrusions can be divided into diorite porphyrites,quartz monzodiorites and monzodiorites.Zircon LA–ICP–MS U–Pb dating demonstrates that diorite porphyrites,quartz monzodiorites and monzodiorites were formed at104±1,114±1,114±1 Ma,respectively.In addition,sulfides in Yanshanian intrusion-related gold mineralization haveδ;S values of 0.2–4.4%,lower than those in Hercynian-Indosinian(1.9–9.8%)orogenic deposits(ca.219–378 Ma)in the Gezhen shear zone.In addition,all these intrusions display close correlations between Eu/EuN*with Th/U,consistent with the differentiation of amphibole,apatite and titanite from a hydrous melt.Moreover,zircon Eu/EuN*in the intrusions are higher than0.4,demonstrating that the magmatic rocks have high water contents and oxygen fugacity values,favorable for gold mineralization.Consequently,the Yanshanian magmatic rocks can be a new potential gold exploration target in the Gezhen shear zone. | Yan Hai Bingtao Li Teng Deng Deru Xu Li Wang Youzhong Xiong Xiaowen Zhang Zhiling Wang Shaohao Zou Zhengpeng Ding Qian Qian Shichao Guo | 2022 | Acta Geochimica2022，41，2： | 0 |
| 5 | A machine learning approach to tracking crustal thickness variations in the eastern North China Craton显示文摘The variation of crustal thickness is a critical index to reveal how the continental crust evolved over its four billion years.Generally,ratios of whole-rock trace elements,such as Sr/Y,(La/Yb)n and Ce/Y,are used to characterize crustal thicknesses.However,sometimes confusing results are obtained since there is no enough filtered data.Here,a state-of-the-art approach,based on a machine-learning algorithm,is proposed to predict crustal thickness using global major-and trace-element geochemical data of intermediate arc rocks and intraplate basalts,and their corresponding crustal thicknesses.After the validation processes,the root-mean-square error(RMSE)and the coefficient of determination(R2)score were used to evaluate the performance of the machine learning algorithm based on the learning dataset which has never been used during the training phase.The results demonstrate that the machine learning algorithm is more reliable in predicting crustal thickness than the conventional methods.The trained model predicts that the crustal thickness of the eastern North China Craton(ENCC)was-45 km from the Late Triassic to the Early Cretaceous,but-35 km from the Early Cretaceous,which corresponds to the paleo-elevation of 3.0±1.5 km at Early Mesozoic,and decease to the present-day elevation in the ENCC.The estimates are generally consistent with the previous studies on xenoliths from the lower crust and on the paleoenvironment of the coastal mountain of the ENCC,which indicates that the lower crust of the ENCC was delaminated abruptly at the Early Cretaceous. | Shaohao Zou Xilian Chen Deru Xu Matthew JBrzozowski Feng Lai Yubing Bian Zhilin Wang Teng Deng | 2021 | Geoscience Frontiers2021，12，5： | 0 |
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