| Located in Youxi of the southern Central Fujiang Rifting Zone, the Meixian lead-zinc deposit has several ore domains, such as Dingjiashan, Guandou, Xiekeng, etc. The mineral deposits mainly occur in volcanic-sedimentary metamorphic rocks of the Mesoproterzoic-Neoproterozoic Longbeixi formation. Some ore bodies occur in post-sedimentry tectonic zone or contact beltw between the Longbeixi formation and granite. Orebody are mainly strata bounded with of greenschist facies metamorphism and deformation. The wall rock alterations are widely developed with silicification, chloritization, epidotization,diopsidation, actinolitization and garnetization. According to orebody structure, ore fabric and mineral paragenesis relationship, the minerazliation of the Meixian lead-zinc deposit was subdivided into three periods.1) Meso-Neo Proterozoic volcanic associated massive sulphide (VMS) depositing period:volcano-sedimentary deposit to form ore sourcebed under rifting environments. With the deep hydrothermal fluid erupting, depositing and accumulating, the massive sulphide deposit formed.2) Caledonian metamorphism period:with the influence of regional metamorphism, metallogenic material (elements) will undergo reactivation, remobilization, precipitation, and result to mineral aggregation, overprinting, recrystallization, enrichment, or forming new orebodies;3) Yanshanian magmatic verprinting period:due to intrusion and associated hydrothermal activity of the granitic magma, skarn type orebodies formed, while previous strata-bounded orebodies were strongly reworking. With detailed LA-ICP-MS zircon U-Pb geochronology and geochemical analysis, it is confirmed that the granitic magmatism is highly fractionated high-K calc-alkaline I-type granitic magma, and intrude in the Late Jurassic (about150Ma),. |
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