| 其他摘要 | Many Cenozoic Pb-Zn-Cu-Ag polymetallic deposits, including the Jinding super giant Zn-Pb deposit, are concentrated in Sanjiang Region, one of the most important base metal mineralization belts in China. The Jinding deposit is the largest Zn-Pb deposit in China, and also is one of the dozen super giant deposits with Zn+Pb reserve more than 10 million tons in the world. The deposit, with enormous metal reserves and young mineralization age, is hosted in sedimentary rocks within the Lanping basin. Although it is genetically associated with the sedimentary evolution of the basin and the hydrothermal acitivities, the ore emplacements are obviously controlled by the overthrusting strike-slip system in Cenozoic after the formation of the basin. Therefore, the Jinding deposit shows a unique metallogenic mechanism with mineralization characterizations different from those of sediment-hosted MVT, SEDEX and SST Zn-Pb deposits. A large number of achievements have been made in the genesis of the Jinding deposit. However, some basic scientific issues, such as mineralization epoch, properties of ore-forming fluids and the source of metals have not been satisfactorily resolved due to its particularity and complexity, which greatly make it difficult to reach a consensus on the origin. Based on progresses in studies on geology and geophisics in the Lanping basin, and new analytical methods, further studies in abnormal enrichment mechanisms of ore-forming metals in the Jinding Zn-Pb deposit are theoretically and practically significant to a systematic understanding in the base metal metallogenesis under continental collisional settings. Based on previously published literatures, systematic field investigations and laboratory analysis have been carried out to identify the symbiotic and associated relationship of minerals and mineral assemblages in the Jinding Zn-Pb deposit. Using techniques of Re-Os dating, in situ sulfur isotopes measured by secondary ion mass spectrometry (SIMS), and nontraditional stable isotopes developed in recent years, a systematic study of Re-Os dating of pyrite, in situ S isotopes, Pb isotopes, Zn isotopes and Hg isotope of sulfide minerals from different mineralization stages, together with fluid inclusion geochemistry, C-O-H isotopes, He-Ar isotopes, Sr isotopes and trace elements of gangue minerals associated with different sulfide mineralizations has been conducted. Based on these scientific results obtained, we comprehensively discussed the age of the mineralization, the attributes of the ore-forming fluids, the sources of ore-forming metals and sulfur, the mechanisms of sulfate reduction, as well as sulfide precipitation, and brought forth the possible mechanism of abnormal enrichment of ore-forming metals in the Jinding Zn-Pb deposit. |
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