Source Of Granite

As a landmark rock of the continent, granite forms the basis of the upper crust of the continent, 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 issue of granite genesis has been the subject of numerous controversies. The debate on the genesis of granite can be seen in the works of Gillully (1948), Pitcher (1993), and Young (2003), and will not be listed here. It should be noted that since the introduction of plate tectonics theory in the 1960s, many explanations for the genesis of granite have been reinterpreted within the theoretical framework of plates. In many cases, understanding may seem to converge, but the actual debate continues.
The misconception of Bowen's (191419221948) theory of basaltic magma crystallization differentiation is that it combines the mineral crystallization sequence with the rock sequence of magmatic rocks from basic to acidic. The experimental results demonstrate that the crystallization differentiation of basaltic magma can only produce a small amount of residual granitic melt, which is in clear conflict with the fact that there are numerous granites in the field (Holmes, 1926; Read, 1957). The mineral reaction series can actually be applied to magma systems of different components. In other words, the initial crystallization from the magma system may not be basic rocks, and the final formation may not be Felsic (acid) rocks, because the nature of rocks 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, Plutonism rigidly binds to a single model, and it is somewhat conjectured that most of the evolution of Igneous rock is due to the cooling, crystallization and separation of basaltic magma invading the crust. The same chemical theory can be applied to other models."
In the 1940s (Gillully, 1948), H H. The "Transformation Theory" represented by Read and N L. The debate among the 'magma theorists' represented by Bowen 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, "Why did the granite come from
The overwhelming understanding of this issue is that granite is formed by partial melting and solidification of various components of rocks in the crust. This view combines two different understandings about the origin of granites in the early period, namely, the magmatic theory (that granites come from the crystallization of magma) and the metamorphic theory (that granites are Sedimentary rock rich in silicon and aluminum that were transformed by granitization under dry or water bearing conditions). It is proposed that granite is the result of ultrametamorphism (deep melting) of crustal rocks, which is of great significance for studying the origin and chemical differentiation of the crust, as they are related to the thermal state of the crust and the composition of the original rock during a specific period, including how much granite magma can be produced, the temperature and quantity and source of water during granite formation, tectonic background, and plate action process, etc.