What is the Archean TTG?
太古宙TTG岩石是什么含义?

The Archean granulite massif and Archean TTG are two big mystery in Archean. Archean TTG has long been a hot topic. It is related to how the early continental crust formed grew and evolved. It has been widely acknowledged that Archean TTG formed either in a subduction zone or a product of melting thickened lower continental crust. However, these understandings were based on a simple comparison between Archean TTG and modern adakite. Instead, the correct comparison should be made between various types of Archean granites. And the Archean crust was abnormally hot and the presence of plate tectonics in Archean is still questioned. As the major component of the Archean crust, Archean TTG reflects the average thickness of the Archean crust. But, thickened crust is a concept compared to normal crust thickness. Consequently, there is a significant misunderstanding in the studies on Archean geology and improper usage of the principle of uniformitarianism. Such principle is only applicable in Phanerozoic and Proterozoic other than Archean. TTG research is a key for us to understand the former plate tectonics and when the plate tectonics started.