Metamorphic turnover at 2 Ga related to two-stage assembly of Columbia ...

• Main Authors: Volante, Silvia, Kirscher, Uwe
• Format: Article in Journal/Newspaper
• Language: English
• Published: ETH Zurich 2024
• Subjects: Greenland
• Online Access: https://dx.doi.org/10.3929/ethz-b-000666245; http://hdl.handle.net/20.500.11850/666245

Understanding the stabilization of cratons and how this is related to the onset of plate-tectonics is among the most important questions in geoscience. The assembly of Earth’s first supercontinent Columbia represents the first lines of evidence for a global subduction network, when the oldest, deep subduction-related rocks have been reported. We combine the low-, intermediate- and high-T/P global metamorphic record with the two-stage assembly of the Nuna-Columbia supercontinent to address the significance of the oldest “cold” rocks (low-T/P) and the related emergence of bimodal metamorphic belts. For this purpose, we analyse two examples from Laurentia (including Greenland) and Australia between 2.0–1.8 Ga and 1.8–1.6 Ga. Two main observations are: (i) a first-stage (2.0–1.8 Ga) amalgamation of the megacontinent Nuna (precursor to Columbia) is characterized by bimodal metamorphism along major mobile belts suturing the megacontinent’s center. In contrast, a second-stage (1.8–1.6 Ga) is dominated by the ... : Scientific Reports, 14 (1) ...