Forms and evolution of plate tectonics on the Archean Earth

It is hotly debated when plate tectonics began to operate on the earth, believed to happen sometime during the Archean. We study here the relationship between metamorphism and drip and plate tectonics during the Archean. We examined metamorphic proxy, and tracked tectonic forms and processes over the Archean by synthesizing (i) zircon U-Pb age spectra and isotopes of samarium and neodymium, (ii) compiling events associated with continental crustal growth and reworking, and (iii) integrating various proxies connected to plate tectonics and special magmatism/tectonics. We propose that plate tectonics started at the latest in the Eoarchean and occurred in the form of accretion or collision without subduction around 3.7 billion years ago (Ga); suggest that 3.3-3.1 Ga and 3.0-2.9 Ga were the time of local subduction initiation and the onset of the global plate tectonics, respectively; confirm the assembly of Kenorland supercontinent at 2.8-2.5 Ga. We finally established a secular evolution model to visualize the evolution of Archean plate tectonics from stagnant to local, regional, and global scales.