矿床地球化学国家重点实验室知识库

Recently, the mineral potential of the area surrounding the granitic batholiths in the Nanling Range was highlighted by the discovery of a series of tungsten and tin deposits or occurrences hosted in or near the Penggongmiao and Guidong batholiths in southern Hunan Province, South China. However, the lack of high precision geochronological data from these deposits has hampered the understanding of their ore genesis and further W-Sn exploration progress. Based on detailed geological investigations, we obtained precise Secondary Ion Mass Spectroscopy (SIMS) zircon U-Pb and muscovite Ar-Ar ages from the greisen-dominated Liuyuan tin deposit and Zhuyuanli tungsten deposit, which are located on the western margin of the Guidong batholith. The results show that the Ar-40/Ar-39 plateau age of muscovite (153.10 +/- 0.96 Ma) from the Liuyuan tin deposit is consistent with the Ar-40/Ar-39 plateau age of muscovite (151.64 +/- 0.96 Ma) from the Zhuyuanli tungsten deposit within analytical error. These data indicate that the W-Sn mineralization in the region occurred during the Late Jurassic, which is significantly later than the emplacement of the Caledonian (Early Paleozoic) ore-hosting Guidong granite batholith, as evidenced by the SIMS zircon U-Pb age data from the Liuyuan greisen (438.1 +/- 2.6 Ma) and the Zhuyuanli greisenized granite (433.8 +/- 3.1 Ma). The remarkable differences in age between the Guidong batholith emplacement and formation of these two W-Sn ore deposits indicate that the regional tungsten and tin mineralization is temporally and genetically associated with possibly concealed Late Jurassic granite at depth rather than with the surrounding Caledonian granite batholith. The uniform W-Sn mineralization age (153-151 Ma) of the Liuyuan and Zhuyuanli deposits suggests that significant Late Jurassic W-Sn ore-forming potential exists along the western margin of the Guidong batholith.