岩石矿物学杂志2025，Vol.44Issue(6)：1340-1358,19.DOI:10.20086/j.cnki.yskw.2025.5075
辽-吉造山带变基性-超基性岩成因机制及其对Ni-Co富集成矿的制约
Petrogenesis of meta-mafic-ultramafic rocks in the Liao-Ji Orogen and implications for Ni-Co enrichment and mineralization
摘要
Abstract
The study of Paleoproterozoic meta-mafic-ultramafic rocks in the North Liaohe Group of the Liao-Ji oro-genic belt in the North China Craton provides critical evidence for understanding regional tectonic evolution.Through detailed field investigations,petrographic observations,and systematic geochemical analyses,combined with previous research findings,this study yields new insights into the petrogenesis and tectonic setting of these rocks.It also presents a preliminary discussion on the intrinsic genetic relationship between the geodynamic mecha-nism of the Liao-Ji orogen and the source of Ni-Co elements.Based on previous data,the protoliths of the meta-mafic-ultramafic rocks have a peak emplacement age of～2 152 Ma and underwent regional metamorphism at ap-proximately 1 882 Ma.Geochemical results indicate that the meta-ultramafic rocks are hornblende-chlorite schists with a cumulate origin.Their LREE enrichment and Nb-Ta-Ti depletion characteristics suggest that the primary magma likely experienced metasomatism by subduction-related fluids.The protoliths of the meta-mafic rocks are all subalkaline tholeiitic basalts,which can be classified into two types.The first type exhibits geochemical features similar to MORB,originating from a depleted asthenospheric mantle source with limited fluid metasomatism.Zircon Hf isotopes from this type provide direct evidence for Paleoproterozoic juvenile crustal growth events in the Liao-Ji orogen.The second type of meta-mafic rock shows significant LREE enrichment and Nb-Ta-Ti negative anoma-lies,indicating that their primary magmas were derived from an enriched lithospheric mantle source that was intensely metasomatized by subduction fluids.Based on the petrogenetic mechanisms and source characteristics of the meta-mafic-ultramafic rocks,this study proposes that they formed in a back-arc basin tectonic setting.The two types of meta-mafic rocks respectively record the complete evolutionary process of the back-arc basin from initial extension(enriched component)to maximum spreading(depleted component).Ni-Co mineralization is closely related to this evolutionary process:back-arc extension facilitated mantle melting and extraction of Ni-Co elements;magmatic underplating and cumulate processes achieved pre-enrichment;the addition of crustal sulfur triggered sulfide melt segregation;and the final collisional orogeny led to the extraordinary enrichment and formation of the ore deposits.关键词
辽-吉造山带/北辽河群/变基性-超基性岩/地球化学/Ni-Co成矿Key words
Liao-Ji orogenic belt/North Liaohe Group/meta-mafic-ultramafic rocks/geochemistry/Ni-Co miner-alization分类
天文与地球科学引用本文复制引用
李同宇,刘福来,王舫,王慧宁,姜杭云,陶鹏..辽-吉造山带变基性-超基性岩成因机制及其对Ni-Co富集成矿的制约[J].岩石矿物学杂志,2025,44(6):1340-1358,19.基金项目
国家重点研发计划项目(2022YFC2903502) （2022YFC2903502）
国家自然科学基金重点支持项目(92062214) National Key Research and Development Program of China(2022YFC2903502) （92062214）
Key Program of National Natural Science Foundation of China(92062214) （92062214）
