According to the metallogenic theory by transmagmatic fluid （TMF）, one magmatic intrusion is a channel of ore-bearing fluids, but not their source. Therefore, it is possible to use TMF＇s ability for injection into ...According to the metallogenic theory by transmagmatic fluid （TMF）, one magmatic intrusion is a channel of ore-bearing fluids, but not their source. Therefore, it is possible to use TMF＇s ability for injection into and for escaping t^om the magmatic intrusion to evaluate its ore-forming potential. As the ore-bearing fluids cannot effectively inject into the magmatic intrusion when the magma fully crystal- lized, the cooling time and rates viscosity varied can be used to estimate the minimum critical thickness of the intrusion. One dimensional heat transfer model is used to determine the cooling time for three representative dikes of different composition （granite porphyry, quartz diorite and diabase） in the Shihu gold deposit. It also estimated the rates viscosity varied in these time interval. We took the thickness of dike at the intersection of the cooling time -- thickness curve and the rates viscosity varied versus thick- ness curve as the minimum critical thickness. For the ore-bearing fluids effectively injecting into the magma, the minimum critical thicknesses for the three representative dikes are 33.45 m for granite porphyry, 8.22 m for quartz diorite and 1.02 m for diabase, indicating that ore-bearing dikes must be thicker than each value. These results are consistent with the occurrence of ore bodies, and thus they could be applied in practice. Based on the statistical relationship between the length and the width of dikes, these critical thicknesses are used to compute critical areas： 0.0003--0.0016 km2 for diabase, 0.014--0.068 km2 for quartz diorite and 0.011-0.034 km2 for granite porphyry. This implies that ore- bearing minor intrusions have varied areas corresponding to their composition. The numerical simulation has provided the theoretical threshold of exposed thickness and area of the ore-bearing intrusion. These values can be used to determine the ore-forming potentials of dikes.展开更多
基金supported by National Program on Key Basic Research Project(973 Progranm)(Grant No.2007CB411304)National Natural Science Foundation of China(Grant No. 90814007)+1 种基金Geological Survey of China Project(Grant No. 1212010911028)China-Russia Cooperation Fund Project (Grant No.40911120079)
文摘According to the metallogenic theory by transmagmatic fluid （TMF）, one magmatic intrusion is a channel of ore-bearing fluids, but not their source. Therefore, it is possible to use TMF＇s ability for injection into and for escaping t^om the magmatic intrusion to evaluate its ore-forming potential. As the ore-bearing fluids cannot effectively inject into the magmatic intrusion when the magma fully crystal- lized, the cooling time and rates viscosity varied can be used to estimate the minimum critical thickness of the intrusion. One dimensional heat transfer model is used to determine the cooling time for three representative dikes of different composition （granite porphyry, quartz diorite and diabase） in the Shihu gold deposit. It also estimated the rates viscosity varied in these time interval. We took the thickness of dike at the intersection of the cooling time -- thickness curve and the rates viscosity varied versus thick- ness curve as the minimum critical thickness. For the ore-bearing fluids effectively injecting into the magma, the minimum critical thicknesses for the three representative dikes are 33.45 m for granite porphyry, 8.22 m for quartz diorite and 1.02 m for diabase, indicating that ore-bearing dikes must be thicker than each value. These results are consistent with the occurrence of ore bodies, and thus they could be applied in practice. Based on the statistical relationship between the length and the width of dikes, these critical thicknesses are used to compute critical areas： 0.0003--0.0016 km2 for diabase, 0.014--0.068 km2 for quartz diorite and 0.011-0.034 km2 for granite porphyry. This implies that ore- bearing minor intrusions have varied areas corresponding to their composition. The numerical simulation has provided the theoretical threshold of exposed thickness and area of the ore-bearing intrusion. These values can be used to determine the ore-forming potentials of dikes.
