Two styles of plate tectonics in Earth's history.

When plate tectonics started to occur on Earth and how it has evolved through time are two of the most fundamental questions in earth sciences. While gravity-driven subducting has been accepted as a critical condition for the operation of plate tectonics on Earth, it is intriguing how the dynamic regime and thermal state of subduction zones have affected the style of plate tectonics in Earth's history. The metamorphic rocks of regional distribution along convergent plate boundaries record reworking of crustal rocks through dehydration and melting at lithospheric depths. The property of regional metamorphism is determined by both dynamic regime and thermal state of plate margins. The two variables have secularly evolved in Earth's history, which is recorded by changes in the global distribution of metamorphic facies series through time. This results in two styles of plate tectonics. Modern-style plate tectonics has developed since the Neoproterozoic when plate margins were rigid enough for cold subducting, whereas ancient-style plate tectonics has developed since the Archean when plate margins were ductile enough for warm subducting. Such a difference is primarily dictated by higher mantle temperatures in the Archean than in the Phanerozoic. The development of plate subduction in both cold and warm realms is primarily dictated by the rheology of plate margins. This leads to a holistic model for the style of plate tectonics during different periods in Earth's history.