As a landmark rock of the continent, granite forms the basis of the upper continental crust, and its formation process is usually closely related to continental tectonism, metamorphism and mineralization. Since the 18th century, when geological science was still in its infancy, the origin of granite has been the subject of many debates. The debate on the origin of granite can be seen in the works of Gilluly (1948), Pitcher (1993) and Young (2003), which will not be listed here. It should be mentioned that since the plate tectonic theory came out in the 1960s, many explanations about the genesis of granite have been put into the theoretical framework of plate to re understand. In many cases, the understanding seems to be consistent, but the actual debate continues.
Bowen's (191419221948) theory of basaltic magma crystallization differentiation was mistaken for the combination of mineral crystallization sequence and magmatic rock sequence from basic to acidic. The experimental results show that the crystallization differentiation of basaltic magma can only produce a small amount of residual granitic melt, which obviously conflicts with the fact that there are many granites in the field (Holmes, 1926; Read, 1957). The mineral reaction series can actually be applied to magmatic systems with different compositions. In other words, the primary crystallization from the magma system is not necessarily the basic rock, and the final formation may not be the felsic (acidic) rock, because the nature of the rock crystallized from the melt depends on the composition of the melt rather than the order of mineral crystallization (Kennedy, 1933). Walton (1960) made the following comments on Bowen's understanding: "There is no mistake in Bowen's chemical theory or in applying it to the separation of basaltic magma, which is still a basic principle of petrology. However, the igneous theory rigidly binds a single model. It is a bit speculative to think that the evolution of most igneous rocks is the result of basalt magma invading the crust to cool, crystallize and separate. The same chemical theory can be applied to other models."
In the 1940s (Gilluly, 1948), H H. "Transformation Theory" represented by Read and N 50. The debate between Bowen as the representative of the "Magma Theory" ended with more and more scholars recognizing the magma origin of granite. However, where did the magma that made up the granite body come from? In Bowen's words, "When the granites?"
For this problem, the overwhelming understanding is that granite is formed by partial melting and solidification of rocks with different compositions in the crust. This view combines two different understandings about the origin of granite in the early period, namely, the magmatic theory (that granite comes from the crystallization of magma) and the metamorphic theory (that granite is a sedimentary rock rich in silicon and aluminum that is transformed by granitization under dry or water bearing conditions). It is proposed that granite is the result of super metamorphism (anatexis) of crustal rocks, which is of great significance to the study of the origin and chemical differentiation of the crust, because they are related to the thermal state of the crust and the composition of the original rock in a specific period, including how much granite magma can be produced, the temperature at the time of granite formation and the amount and source of water, the tectonic setting and the process of plate action, etc.
