Abstract:

The Xinping granite-porphyry occurring in the Xinping gold mining area is located in the middle part of the Dayaoshan Au metallogenic belt, eastern Guangxi Province. During our recent field geological survey, a gold deposit was found in contact zone between the porphyry and its wall rocks, whereas quartz-vein-typed molybdenum orebody and mineralized spot were also firstly recognized inside of the intrusion. These suggest that the Au-Mo-polymetallic mineralization is closely related to the granitic igneous activity. Zircons of the granitic porphyry are analyzed using LA-ICP-MS U-Pb isotopic method, which gives a weighted mean 206Pb/238U age of (462.9 ± 6.4) Ma. It reveals a midOrdovican magmatic timing, providing a lower constraint for the mineralization age. The Xinping porphyry samples show REE characteristics akin to those of the granite-porphyries occurring in nearby Gupao, Yuanzhuding and Dali minging areas, indicative of similar nature of source rocks and petrogenesis. Thus, a further potential is predicted by this study in exploring porphyry-related gold and molybdenum deposits in the Xinping gold field.

Key words: granite-porphyry, Xinping gold deposit, Au-polymetallic mineralization, Dayaoshan metallogenicbelt, eastern Guangxi Province