The genesis and tectonic environment of granite

As a product of specific geological background, the petrological, mineralogical and geochemical characteristics of granite should record the tectonic background of its formation.Thus, if we can obtain the formation and tectonic background information of the large amount of granite exposed on the surface, it will provide important information for us to reverse the tectonic evolution history.The problem, however, is not so simple.Even for some granites with known tectonic environments, their source zone inheritance and melt differentiation can affect the material composition of the resulting granites, resulting in the loss of correspondence with the tectonic environment.

Since the 1990 s, people have realized that most of the granite is the asthenosphere and lithosphere mantle heat input into the earth's crust cause a product of the interaction between crust and mantle, mantle can be released from derived heat flow, the mixture of volatile fluid, and the mantle source material, until the mantle partial melting, and other forms of participation in the formation of granite;The interaction between the mantle and the crust can also result in underplating, delamination or subduction.Therefore, the relationship between granite formation and geotectonic environment actually reflects the relationship between a certain stage of geotectonic evolution and the interaction between crust and mantle.In addition, it is also recognized that granites are one of the basic components of orogenic belts. In addition to being influenced by tectonic environment, their composition changes are also restricted by the following major factors: Different source rock composition;Different melting conditions;Chemical and physical reactions between basic and acidic components;The earth's crust is stained;5. Magma evolution mechanism, etc.

Based on the above consideration, granite, genetic types and tectonic environment research is still on the leading edge of the study of contemporary granite, but a new generation of classification of tectonic environment should not only consider the source rock and classical type of plate tectonic dynamics, and should be in the asthenosphere and lithosphere mantle heat input into the crust of the wider the scope and time evolution of granite formation of the tectonic environment.Should emphasize that the granite is a product a variety of geologic factors and their interaction, but overall the asthenosphere and lithosphere mantle heat input of crust and mantle interaction control is particularly important, therefore, should take regional granite genesis and crust-mantle interaction, lithosphere 3 d structure and evolution, the asthenosphere upwelling and the magma source area, the local conditions, and magma evolution mechanism etc.In this way, a framework of their interrelations can be established, and the tectonic environment in which they were formed and the mechanism and mechanism of heat transfer can be traced.