Brief Introduction To Continental Growth Research
Continental growth is a very old hypothesis, but it is
also a heated discussing question for nearl
y all geologist. For a long period of time, scholars attempt to give answers to it via different ways. Nowadays, two kinds of theories have been widely accepted. The first is based on the theory of Plate Tectonics. The latter is based on a new research achievement called Mantle Plume intended to solve the problem of the growth of continental plate. The passage is aimed at show the main sites for continent to growth and try to explain the relationship between three kinds of plate convergence and continental growth. Key words: continental growth; Plate tectonics; Mantle plume; main sites; plate convergence
1. Main sites for continental growth An explanation from the theory of Plate Tectonics According to the theory of Plate Tectonics, the movements of plates are mainly of horizontal movement, and tectonic deformations are mainly occurred in the area of plate boundaries. The basic theory of plate tectonics point of view: the lithosphere plate block likes a wood floating in water, which is drifting on the
asthenosphere .Their movements are not synchronized. Ocean lithosphere grows through the expansion of mid-ocean ridge. Old
lithosphere is broken up and returned to the asthenosphere through subduction zone. New crust is generated at the place of plate boundaries via volcanic island arc and continental margin of the subduction zone’s volcanism，while arc spreading and arc basin volcanism happen in the arc. Such a movement is driven by shallow asthenosphere’s mantle convection. So lots of scholars believe that continental growth mainly happens at the places of plate boundaries. View by plate tectonics, continental growth is mainly through the island arc subduction zone’s magmatic activity to achieve. Another explanation from the theory of Mantle plume The theory of mantle plume is a newly developed theory, which are based on solving the problem of the movement continental plate. According to the theory, the role of mantle plume, on the one hand, break up the ancient continent. But some of the mantle plume activities don’t make the landmass crack, especially the mantle plume activity happening about 500Ma and 250 Ma. On the contrary, these large igneous Province connect separated landmass. On the other hand, some mantle plume activities taking place in continental plate make a contribution to the growth of
continent, for example, the E’Mei basalt body. The lower class crust and lithosphere crust material can return to the asthenosphere the Large igneous Provinces lithosphere can return to the
asthenosphere through the delamination and detachment of large igneous province. From the main idea of the theory, It’s obvious that continent growth can happen both at the boundaries of plate and in the continent plate.
2. The relationship between three kinds of plate convergence and continental growth.
Convergent plate boundary is location where two or more plates get closer or collide. earthquakes and volcanoes often happen because of the edge of the location of the pressure of collision, friction and melting of the plate material. If one plate is oceanic plates, it will sink into the other plate, returning to the asthenosphere. If both plates are continental plates, mountain ranges form as a result of continental collision. Plate convergence can be classified to three types according to their tectonic environment. Both Plate tectonic theory and Mantle Plume theory consider that continent growth happen at the boundaries of plate. I believe that all three types of plates convergence can generate continental crust.
Ocean-Ocean (oceanic island arcs)