| Popis: |
The Wurinitu molybdenum deposit, located in Honggor, Sonid Left Banner of Inner Mongolia, China, is recently discovered and is considered to be associated with a concealed fine-grained granite impregnated with molybdenite. The wall rocks are composed of Variscan porphyritic-like biotite granite and the Lower Ordovician Wubin'aobao Formation. LA-ICP-MS zircon U-Pb dating of the fine-grained granite reveals two stages of zircons, one were formed at 181.7±7. 4 Ma and the other at 133.6±3.3 Ma. The latter age is believed to be the formation age of the fine-grained granite, while the former may reflect the age of inherited zircons, based on the morphological study of the zircon and regional geological setting. The Re-Os model age of molybdenite is 142.2±2.5 Ma, which is older than the diagenetic age of the fine-grained granite. Therefore the authors believe that the metallogenic age of the Wurinitu molybdenum deposit should be nearly 133.6±3.3 Ma or slightly later, i.e., Early Cretaceous. Combined with regional geological background research, it is speculated that the molybdenum deposits were formed at the late Yanshanian orogenic cycle in the Hingganling-Mongolian orogenic belt, belonging to the relaxation epoch posterior to the compression and was associated with the closure of the Mongolia-Okhotsk Sea. |
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