科研之友
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摘要
The Luming-molybdenum deposit, discovered in recent years, is a large-size porphyry molybdenum deposit in the Yichun-Yanshou metallogenic belt. This deposit area mainly exposes the monzonitic granite, granitic porphyry, granodiorite and porphyroid granodiorite. The monzonitic granite and granitic porphyry, occurring as the host rocks of the deposit, with similar geochemical characters of low Sr and high Y and others, formed in Early Jurassic ages of 194. +/- 0.7Ma and similar to 184Ma. Both the granodiorite and porphyroid granodiorite, with dark enclaves, reveal their formation ages of 176.2 +/- 2.1Ma which is consistent with the mining deposit formation age acquired from Re-Os dating carried on the molybdenite, and show geochemical characters of high-K calk alkaline series, high-Sr and low Y. Their geochemical characters are similar to the adakites in eastern China. Both the granodiorite and porphyroid granodiorite are also suggested to be the parent rocks for mineralization process of porphyry deposit and to have relationship with multiple Mesozoic significant geological events occurred in eastern China and its neighbor area. The intrusion of adakited magma enriched in Na, LILE and ore-forming materials, generated by the partial melting of subducted slabs at high fO(2) condition results in the formation of porphyry Luming-molybdenum deposit. The discovery of adakite in Luming suggests that the shrink and elimination of Pacific plate has occurred at the Middle Jurassic, and the relating magmatism and ore-forming process should occur at wider region but one or some rocks, and more extensive petrology studies can provide important clues to discover more porphyry deposits in this area.
