透岩浆流体成矿体系

Metallogenic systems on the transmagmatic fluid theory.

根据透岩浆流体成矿理论,熔浆体系与含矿流体体系可以看作是两个相互独立的地质体系,它们因相互需要而耦合在一起形成一个复杂的混合体系。当熔浆与流体发生解耦时,可以在不同的边界条件下发生不同类型的成矿作用。因此,可以将透岩浆流体成矿体系进一步划分成正岩浆成矿体系、接触带成矿体系、远程热液成矿体系和火山热液成矿体系。如果熔浆具有很强的流体圈闭能力,所有的含矿流体都将被封存在岩浆体内,并随着岩浆的固结而析出成矿物质,形成正岩浆矿床。当岩浆具有较高的渗透率且含矿流体逸出岩浆体时,如果岩浆的直接围岩具有较强的捕获成矿物质的能力,即发生接触带成矿作用。否则,含矿流体将在岩浆热驱动下远离岩浆体,形成远程热液矿床。如果有利的流体通道直达岩浆体,含矿流体甚至可以喷出地表或其附近,形成火山热液矿床或水底喷流沉积矿床。这种理论分析似乎与许多成矿事实相吻合,可以有效地指导区域成矿预测和矿床勘探。

The melt system and the ore-bearing fluid system can be seen as two independent geological systems according to the theory of transmagmatic fluid metallogenesis. They have coupled to form a complex mixing system because of their needs each other when the magma and ore-bearing fluids emplace up to the shallow level of crust. Decoupling between the melt and the fluid systems induces to the different type of minerallisation under the different boundary conditions. Therefore, the metallogenic system of the transmagmatic fluids can be subdivided into the following systems： the orthomagmatic, the contact-metasomatic, the epithermal, and the volcano-hydrothermal. If the melt has higher ability to entrap the ore-bearing fluids, all of the fluids will be trapped in the magma body and separate out the ore-forming materials from the melt with its consolidation to form the orthomagmatic deposit. If the magma body is easily percolated and the ore-bearing fluids can be separated from the melt, the contact-metasomatic deposit is formed if the surrounding rocks of the magma body have strong ability to entrap the ore-forming materials. Otherwise, the ore-bearing fluids will flow far from the magma body due to the driving force of the magma heat, and form the epithermal deposits. When a favourable channel is connected to the magma body, the ore-bearing fluids even can be erupted to or near the surface and form volcano-hydrothermal or VMS deposits. This theoretical analysis seems better coincide with the observations, and hence the theory of the transmagmatic fluids may effectively serve the regional prospecting and exploration of the mineral deposits.