Gang Chen, Xiuqing Yang, Changhui Ke, Yanwen Tang, Maohong Chen
{"title":"The shallow marine VMS copper deposit of Yushui, Eastern Guangdong, South China: evidence from geology, geochronology, and geochemistry","authors":"Gang Chen, Xiuqing Yang, Changhui Ke, Yanwen Tang, Maohong Chen","doi":"10.1007/s00126-023-01232-5","DOIUrl":null,"url":null,"abstract":"<p>Many massive sulfide deposits have been discovered in the Upper Paleozoic rift-related volcaniclastic sequence in South China, among which the Yushui copper deposit is the most important due to its high grade. The deposit has been variably attributed as SEDEX (sedimentary exhalative) or MVT (Mississippi valley type). The Yushui copper deposit in Guangdong (South China) contains stratiform bornite-chalcopyrite orebodies (102.1 kt Cu @ 3.5%, 186.6 kt Pb @ 4.29%, 117.6 kt Zn @ 2.91%, and 339 t Ag @ 112 g/t) developed along the contact between Upper Carboniferous dolostone and Lower Carboniferous pebbly quartz sandstone, which indicates a shallow marine deposition environment. The Yushui deposit comprises an upper massive sulfide orebody and a lower stockwork orebody with intense alteration. In this study, we newly identified Carboniferous tuffs and syn-volcanic faults in the footwall, and exhalites in the hanging-wall. Hematite from the Cu ores yielded a U-Pb age of 320 ± 15 Ma (MSWD = 2.1, <i>n</i> = 57), and hydrothermal dolomite yielded a Sm-Nd isochron age of 308.1 ± 4.6 Ma (<i>n</i> = 7; MSWD = 0.94), which constrains the timing of mineralization at Yushui. These ages are coeval with the Carboniferous host rocks. Combining the evidence from the geological features (syn-volcanic faults, volcanic rocks, exhalites) and hematite trace element compositions, we suggest that the Yushui is a shallow marine VMS (volcanogenic massive sulfide) deposit. The Sr-Nd isotope composition of hydrothermal dolomite (<i>ε</i><sub>Nd</sub> ~−12) indicates that the ore-forming materials were originated from the crustal basement. The Yushui copper deposit was likely formed during the Late Carboniferous continental back-arc extension in eastern South China. The regional extension may have caused enhanced heat flow, which promoted fluid convection in the basement rocks. In addition, we suggest that volcanic rocks and disseminated chalcopyrite-pyrite mineralization in the Lower Carboniferous quartz sandstone and exhalites are good indicators for regional VMS prospecting.</p>","PeriodicalId":18682,"journal":{"name":"Mineralium Deposita","volume":null,"pages":null},"PeriodicalIF":4.4000,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mineralium Deposita","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s00126-023-01232-5","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Many massive sulfide deposits have been discovered in the Upper Paleozoic rift-related volcaniclastic sequence in South China, among which the Yushui copper deposit is the most important due to its high grade. The deposit has been variably attributed as SEDEX (sedimentary exhalative) or MVT (Mississippi valley type). The Yushui copper deposit in Guangdong (South China) contains stratiform bornite-chalcopyrite orebodies (102.1 kt Cu @ 3.5%, 186.6 kt Pb @ 4.29%, 117.6 kt Zn @ 2.91%, and 339 t Ag @ 112 g/t) developed along the contact between Upper Carboniferous dolostone and Lower Carboniferous pebbly quartz sandstone, which indicates a shallow marine deposition environment. The Yushui deposit comprises an upper massive sulfide orebody and a lower stockwork orebody with intense alteration. In this study, we newly identified Carboniferous tuffs and syn-volcanic faults in the footwall, and exhalites in the hanging-wall. Hematite from the Cu ores yielded a U-Pb age of 320 ± 15 Ma (MSWD = 2.1, n = 57), and hydrothermal dolomite yielded a Sm-Nd isochron age of 308.1 ± 4.6 Ma (n = 7; MSWD = 0.94), which constrains the timing of mineralization at Yushui. These ages are coeval with the Carboniferous host rocks. Combining the evidence from the geological features (syn-volcanic faults, volcanic rocks, exhalites) and hematite trace element compositions, we suggest that the Yushui is a shallow marine VMS (volcanogenic massive sulfide) deposit. The Sr-Nd isotope composition of hydrothermal dolomite (εNd ~−12) indicates that the ore-forming materials were originated from the crustal basement. The Yushui copper deposit was likely formed during the Late Carboniferous continental back-arc extension in eastern South China. The regional extension may have caused enhanced heat flow, which promoted fluid convection in the basement rocks. In addition, we suggest that volcanic rocks and disseminated chalcopyrite-pyrite mineralization in the Lower Carboniferous quartz sandstone and exhalites are good indicators for regional VMS prospecting.
期刊介绍:
The journal Mineralium Deposita introduces new observations, principles, and interpretations from the field of economic geology, including nonmetallic mineral deposits, experimental and applied geochemistry, with emphasis on mineral deposits. It offers short and comprehensive articles, review papers, brief original papers, scientific discussions and news, as well as reports on meetings of importance to mineral research. The emphasis is on high-quality content and form for all articles and on international coverage of subject matter.