科研之友
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摘要
The unique of the lithosphere in the earth is that it contains large amounts of granite, which does not occur elsewhere in the solar system. The continental crust of the earth is mainly composed of granite, whereas the oceanic crust is dominated by basalt. Unlike the short-lived oceanic crust which may have only existed in 200 to 300Myr on the earth, the continental crust can survive in 4000 to 4500Myr. The granite in the earth thus may record the history of the formation and evolution of the continental lithosphere of the Earth. The earliest continental crust is composed of Tonalite-Trondhjemite-Granodiorite (TTG) suite, however. TTG is neither a product of fractionation of magma ocean, nor of partial melting of the mantle. The origin of TTG is thus crucial for understanding the origin of continental crust. Extensive continental growth and cratonization occurred in Phanerozoic, which was associated with massive granite production and mineralization. All these issues are difficult to be explained by the current theory of plate tectonics. The answers for the key issues on the granite may trigger the new theory of solid earth sciences. Reworking of continental crust is related to intensive tectonothermal events in the earth as proposed by Prof. Guoda Chen and his "platform activation" model. Mesozoic large-scaled intracontinental deformation and extensive magmatism in East China may provide an ideal natural laboratory to study the dynamic mechanism of the continental reactivation and to understand plate tectonics and cratonization. Presence of voluminous granite may change the internal structure of the earth and the stability of continental lithosphere, leading to the craton re-activation or destruction. However, it remains unclear how these processes worked in the history of Phanerozoic continental crust. New theory rather than classic plate tectonics is desired to establish to explain the granite issues. The change from routine granite geochemistry to continental growth will make a real breakthrough in the theory of solid earth sciences in the 21st century. The 540th Xiangshan Conference on the key issues of granite research is a milestone to prompt the research of granite and continental evolution, rheology and thermodynamics in the next five years in China.
- 出版日期2017
- 单位中国科学院地质与地球物理研究所; 浙江大学; 中国科学院地质与地球物理研究所兰州油气资源研究中心
