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| Re-Os Isotopic Dating of Pyrite from the Neoproterozoic Datangpo Formation#br# in Tongren, Guizhou and Its Geological Significance |
| WANG Dan1,2， LIAO Zhen-wen1， WANG Sheng-wei1， JIANG Xiao-fang1， LIN Fang-cheng1 |
(1.Chengdu Center, China Geological Survey, Chengdu 610081， China;
2.Sichuan Institute of Geological Survey, Chengdu 610081, China) |
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Abstract Eight pyrites from the manganese-bearing rock series of the First Member of Neoproterozoic Datangpo Formation are used for Re-Os isotopic dating at Xixibao orefield in Tongren area, Guizhou province. The analyses yield an isochronic age 459±16 Ma, significantly later than the interglacial depositional age of Datangpo Formation (670~635 Ma), which suggest that the Datangpo Formation was probably affected by the tectonic 〖JP〗thermal activity of Late Caledonian. The pyrites also show high Re, low Os abundance, high Re/Os and 187Os/188Os ratio. The initial 187Os/188Os value is 1.02±0.41, significantly higher than the eigenvalue of mantle magma, which indicate the ore-forming materials are mainly derived from the crustal source.
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