{"title":"Orogenic Gold Deposits of Northern Transbaikalia, Russia: Geology, Age, Sources, and Genesis","authors":"A. V. Chugaev","doi":"10.1134/S0016702924700484","DOIUrl":null,"url":null,"abstract":"<p>The paper presents newly obtained and summarizes preexisting data of long-term geochronological and isotope studies of orogenic mesothermal gold deposits in the world’s largest Lena metallogenic province and reviews interpretations of their genesis. Geochronologic data indicate that the gold mineralization was formed during three ore-forming Paleozoic events. The early Late Ordovician–Early Silurian (450–430 Ma) event produced the abundant veinlet—disseminated gold–sulfide mineralization in Neoproterozoic carbonaceous terrigenous–carbonate rocks of the Baikal–Patom foldbelt (BPB). The mineralization was formed simultaneously with regional metamorphic processes. The rejuvenation of hydrothermal activity in the BPB resulted in gold-bearing quartz veins, which was produced in the Middle Carboniferous (340–330 Ma) in relation to postcollisional granitoid magmatism. The latest ore-forming event occurred in the Early Permian (290–280 Ma) and affected exclusively in Precambrian structures of the Baikal-Muya foldbelt (BMB). It was synchronous with the development of intraplate alkaline and subalkaline magmatism in the region. Newly obtained and preexisting isotopic-geochemical (<sup>87</sup>Sr/<sup>86</sup>Sr, <sup>143</sup>Nd/<sup>144</sup>Nd, Pb–Pb, and δ<sup>34</sup>S) data indicate that the mesothermal ore-forming systems of northern Transbaikalia were heterogeneous in their isotopic characteristics, which distinguishes them from the ore–magmatic (intrusion-related type) systems. Comparison of the Sr, Nd, and Pb isotopic composition of the ores and rocks, including magmatic rocks coeval with the gold mineralization, indicates that the Precambrian continental crust was the dominant source of mineral-forming components for the hydrothermal systems of the gold deposits. The contribution of the magmatic source to the genesis of the orogenic gold mineralization was limited and is identifiable only for the Early Permian ore-forming systems of the BMB, for which the input of metals from alkaline mafic melts was suggested.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.7000,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702924700484.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geochemistry International","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1134/S0016702924700484","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
The paper presents newly obtained and summarizes preexisting data of long-term geochronological and isotope studies of orogenic mesothermal gold deposits in the world’s largest Lena metallogenic province and reviews interpretations of their genesis. Geochronologic data indicate that the gold mineralization was formed during three ore-forming Paleozoic events. The early Late Ordovician–Early Silurian (450–430 Ma) event produced the abundant veinlet—disseminated gold–sulfide mineralization in Neoproterozoic carbonaceous terrigenous–carbonate rocks of the Baikal–Patom foldbelt (BPB). The mineralization was formed simultaneously with regional metamorphic processes. The rejuvenation of hydrothermal activity in the BPB resulted in gold-bearing quartz veins, which was produced in the Middle Carboniferous (340–330 Ma) in relation to postcollisional granitoid magmatism. The latest ore-forming event occurred in the Early Permian (290–280 Ma) and affected exclusively in Precambrian structures of the Baikal-Muya foldbelt (BMB). It was synchronous with the development of intraplate alkaline and subalkaline magmatism in the region. Newly obtained and preexisting isotopic-geochemical (87Sr/86Sr, 143Nd/144Nd, Pb–Pb, and δ34S) data indicate that the mesothermal ore-forming systems of northern Transbaikalia were heterogeneous in their isotopic characteristics, which distinguishes them from the ore–magmatic (intrusion-related type) systems. Comparison of the Sr, Nd, and Pb isotopic composition of the ores and rocks, including magmatic rocks coeval with the gold mineralization, indicates that the Precambrian continental crust was the dominant source of mineral-forming components for the hydrothermal systems of the gold deposits. The contribution of the magmatic source to the genesis of the orogenic gold mineralization was limited and is identifiable only for the Early Permian ore-forming systems of the BMB, for which the input of metals from alkaline mafic melts was suggested.
期刊介绍:
Geochemistry International is a peer reviewed journal that publishes articles on cosmochemistry; geochemistry of magmatic, metamorphic, hydrothermal, and sedimentary processes; isotope geochemistry; organic geochemistry; applied geochemistry; and chemistry of the environment. Geochemistry International provides readers with a unique opportunity to refine their understanding of the geology of the vast territory of the Eurasian continent. The journal welcomes manuscripts from all countries in the English or Russian language.