Figure 1
From: Metamorphic turnover at 2 Ga related to two-stage assembly of Columbia
Metamorphic T/P (C°/GPa) records versus ages (Ga) modified after Brown and Johnson71, where three types of metamorphism are identified: high-T/P (red), intermediate-T/P (orange) and low-T/P (blue). Bimodal metamorphism (marked by the red and orange arrows) and associated appearance of the first low-T/P metamorphic rocks (blue circles) can be related to the first supercontinent cycle with the assembly of the megacontinent Nuna, followed by the supercontinent Columbia25. Rough durations of megacontinent/supercontinent pair of Nuna/Columbia and Gondwana/Pangea are based on25. Stars indicate the metamorphic rock record marking the final assembly of the supercontinent Columbia at 1.6 Ga. This compilation is superimposed to a histogram and probability curve for the metamorphic age record.
