GOLD ORIGIN AND FLUID ORE-FORMING EFFECT OF ZHAO-YE ORE DEPOSITS CONCENTRATING AREA IN JIAODONG, SHANDONG, CHINA
Deng Jun1, Yang Liqiang2, Liu Wei2, Sun Zhongshi3, Li Xinjun2, Wang Qingfei1
1. China University of Geosciences, Beijing 100083; 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100101; 3. College of Earth Sciences, Jilin University, Changchun 130061
Based on geological analysis, taking the Zhao-Ye gold ore-deposits concentrating area for example and applying modern fractal theory, mathematical geology and computer simulation, a thorough study was made on ore-source system, fluids flowing and ore-forming effect, which played the roles of internal cause, external cause and evolution of ore-bearing properties respectively. The results are summaried as follows. 1)The metallogenic system is a super-complex entirety. It is made up of multi level temport-spatial scale, manifold ore-controlling parameters and multifarious processes. The ore-forming process is one expression of dynamic functions of the Earth. It is a complex non linear dynamic process. Dynamics is key that defines the evolution and final outcome of the system. 2)Ore source system consists of initial, intermediate and direct ore-source rocks, such as the Jiaodong, Jingshan and Fenzishan Groups, and the Linglong-type granites provides materials for mineralization. While the Guojialing-type granites may not only provide ore-forming materials partly, but also play a role as "hot engine". There is little probability for the Penglai Group and the Luanjiahe type granites to provide ore-forming materials. 3)Gold mineralization is a complex ploy staged and ploy sourced process. It started with Archean tholeiites fractionated from the ancient mantle and underwent shear, regional metamorphism and anatexis. Gold was enriched gradually in those tectonic thermal dynamic processes. Mesozoic shear remelting granites provided ore-forming materials directly. 4) Remobilization, migration and enrichment of ore-forming material generated by compressional extensional shear tectonics are main cause of mineralization. The decisive factors of gold mineralization are the geochemical characteristics of ore-forming elements and the features of ore-forming fluids. 5) The temperature gradient belts around the rock body after its intrusion are one of the main dynamics for hydrothermal mineralization. 6) The flow rate of ore-forming fluid can accelerate the formation of mixed hydrothermal solution, and the shear crushing zone is an advantageous ore-forming place with strong transportation and action. 7) Gold deposits are formed especially by long range moving mantle fluid, which is more-important to gold origin and rich mechanism in moving fluid. The key of giant gold origin and enrichment is link up for three kinds of gradations of circulatory system of Au bearing fluids: the C-H-O bearing fluid in mantle, the Si-bearing one in middle lower crust, and the S bearing one in shallow surface. Because of the three kinds of fluids linking up and mixing each other, the time of circulatory system of Au bearing fluids gets longer, the quantity of extraction of ore-forming elements gets larger, the abundance of gold gets higher; and the gold ore-deposit concentrating area gets formed finally.
Deng Jun,Yang Liqiang,Liu Wei et al. GOLD ORIGIN AND FLUID ORE-FORMING EFFECT OF ZHAO-YE ORE DEPOSITS CONCENTRATING AREA IN JIAODONG, SHANDONG, CHINA[J]. Chinese Journal of Geology, 2001, (3): 257-268.