Abstract:

According to the metallogenic theory of the transmagmatic fluids, the magma body is not the source of orebearing fluids, but the channel for the fluids. Thus, it will be an effective way to estimate the ore forming potential by calculating the content of fluids injected into the magma body. Onedimensional heat transfer model is used to calculate the cooling time with different thicknesses of three representative types of dikes (granite porphyry, quartz diorite and diabase) in Shihu gold mine. The change rate of magma viscosity during the cooling is also estimated. Assuming that these magmas have been emplaced at ～6 km depth and that the orebearing fluid could not be effectively injected into the magma body only after these magmas were fully crystallized, we obtained the minimum critical thickness of mineralization of three representative types of dikes as follows: 3345 m for granite porphyry, 822 m for quartz diorite and 102 m for diabase in Shihu gold mine. Simulation results are consistent with the occurrence of ore bodies, suggesting that they are of practical value. According to the length/width ratio of the dike, the minimal critical oreforming intrusion outcrop area is estimated: 3121561 m2 for diabase, 00140068 km2 for quartz diorite and 00110034 km2 for granite porphyry. This kind of estimation provides a qualitative standard for field geological prospecting, and has certain reference value for rapid exploration.

Key words: dike, cooling time, numerical simulation, high level intrusion, critical thickness, Shihu gold mine; , transmagmatic fluids