Earth-like planets in the solar system and the moon have similar core-mantle-shell structures, but only the earth where humans live has a felsic continental crust. In most cases, the continental crust is much older than the oceanic crust. The oldest continental crust rocks are as old as 4 billion years, the oldest zircon is as old as 4.4 billion years, and the oldest oceanic crust is no more than 250 million years old. In this sense, the continental crust preserves more information about the geological evolution history of the earth than the oceanic crust. The mainland provides a suitable living place and natural resources for human beings. Therefore, when, where and how the mainland originated, proliferated, transformed and even destroyed is a very important scientific issue in earth science. However, there are still many controversies about these issues.

Figure 1 Spatial distribution of global craton

Research by Academician Zhu Rixiang from Institute of Geology and Geophysics of China Academy of Sciences, Academician Zhao from Northwest University and Academician Xiao Wenjiao from Xinjiang Institute of Ecological Geography of China Academy of Sciences shows that:

(1) Archaean continent with felsic crust originated from the ocean platform formed by island arc or mantle plume under plate tectonic system.

(2) The island arc model under the plate tectonic system can well explain the genesis of Archean tonalite-adamellite-granodiorite (TTG), in which high-pressure TTG is considered as the result of partial melting of subduction plates, low-pressure TTG (equivalent to calc-alkaline granitoids) is derived from partial melting of neobasaltic crust, and Cenozoic crust itself is formed by partial melting of mantle wedge caused by fluid released by subduction plates. However, the island arc model can not well explain many characteristics of Archean greenstone terrane, such as the lack of a large number of andesite, Komatiite 1600 high temperature formation environment, TTG suite of craton scale, large-scale dome structure and counterclockwise P-T trajectory with the characteristics of ancient craton metamorphism and deformation.

(3) The model of mantle plume ocean floor plateau can reasonably explain the genesis of Archean greenstone and TTG rock combination, in which tholeiite and coeYan Ma in greenstone are derived from molten magma at the head and tail of mantle plume, dacite, rhyolite dacite and rhyolite are derived from partial melting of the earth's crust, and TTG is derived from partial melting of basalt at the bottom of ocean floor. The ocean floor plateau model can also explain Archean dome structure, counterclockwise P-T trajectory, lack of blue schist and double metamorphic belt.

(4) Since the emergence of plate tectonics on the earth, the Archean continental core has experienced a process of proliferation or growth due to the subduction of the surrounding marine lithosphere, and the formation and proliferation of young arcs is the main mechanism of continental growth in the early history of the earth.

(5) Archean continental core formed a continent through island arc magmatism and combined lateral growth in Proterozoic. In Paleoproterozoic (265,438+0-65,438+0.8 billion years), the global continents collided and built mountains, forming the first supercontinent on earth-Nuna continent (also known as Columbia continent). The Cordillera Mountains in Central Asia, North America and Tasmanide Mountains in eastern Australia are the best examples of Phanerozoic continental growth.

(6) The growth of giant subduction-accretion complex, the retreat of subduction plate, the subduction of ocean ridge and the formation of intracontinental subduction system are the main processes leading to continental growth. Collision orogeny may be a sign of the transformation from Archean plate structure (proliferation) to modern plate structure (proliferation and collision).

Fig. 2 schematic diagram of horizontal and vertical structural heterogeneity of continental lithosphere

(7) In the evolution process of continental lithosphere, besides lateral proliferation or vertical growth, it also experienced episodic transformation, which led to widespread horizontal and vertical structural heterogeneity. The complex structure, inherent chemical buoyancy and high strength of the lithosphere are the basic factors for the long-term stable existence of the ancient continent.

(8) Since the emergence of plate tectonics 3-2.5 billion years ago, the growth rate of the continent has decreased, while the continental transformation has become remarkable, which is mainly related to ocean subduction and continental collision in the process of supercontinent assembly and the deep mantle process.

(9) Continental transformation usually occurs in the weak lithosphere at the continental margin or within the continent, and generally does not affect the overall stability of the continent. However, in the stable craton region, remarkable continental transformation did occur, which strongly activated the craton and even caused the destruction of the craton lithosphere.

(10) The destruction of the craton is mainly attributed to the long-term oceanic subduction. Ocean subduction can lead to the softening and deformation of craton lithosphere through the input of water and other volatiles and obvious tectonic stress. Although the mantle plume beneath the plate may affect the plate movement and the evolution of the craton lithosphere, it plays a relatively small role in the process of continental transformation and destruction.

Fig. 3 Geological model of continental origin, proliferation and transformation

This achievement was supported by the National Natural Science Foundation (9 1958209, 4 1774058). The research results were published in the international authoritative academic journal Geophysical Review (Zhu Rixiang *, Zhao, Xiao Wenjiao, Tang). The origin, proliferation and transformation of the mainland [J]. Geophysical review, 202 1, 59: e20 19RG000689. DOI: 10. 1029/20 19rg 000689).

Proofreading: Liuqi County, Zhou Xingxing.