APPLICATION OF PB ISOTOPE FOR QUANTITATIVE FORECASTING OF BLIND ORE DEPOSITS:A CASE STUDY FROM THE HANSHAN GOLD DEPOSIT IN THE NORTHWESTERN QILIAN OROGENIC BELT
LI Zhonglan1, 2, CUI Xuejun1, LIU Hongying3 , WANG Ran1 and Xu Lifeng1,2 (1.Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, GD 510640, China; 2.Graduate University of Chinese Academy of Sciences, Beijing 100049, China; 3.Heze Bureau of Land and Resources, Heze City, Shandong 274000, China)
This paper applies a new method of Pb isotopes for predicting the blind ore bodies of the Hanshan gold deposit in the northwestern Qilian orogenic belt. The results show that: (1) The V1 and V2 values display regular increase from west to east, suggesting an obvious decrease of the ore body revelation depth from west to east, with the largest revelation depth of the blind ore body up to 1047 m. Meanwhile, the blind ore body thins out toward the east. (2) The average hidden coefficient (Rs) of the Hanshan ore deposit is 3.68, indicating that the predicted reserves for the ore deposit is around 107 tons of gold. The Hanshan gold deposit is probably a superlarge gold deposit. Similarly, the hidden ore bodies of the western Yingzuishan gold deposit also show eastward dipping. The absence of Pb isotope data with V2 between 40 and 60 in these two gold deposits suggests the possible existence of ore bodies, which are not yet found at present. Our results imply that more attention should be paid in looking for such blind ore bodies in future exploration of these two gold deposits.