Coexisting divergent and convergent plate boundary assemblages indicate plate tectonics in the Neoarchean

This study reports coexisting Neoarchean divergent and convergent plate boundary rock assemblages, providing new evidence for the operation of plate tectonics 2.55-2.51 billion years ago; and also suggests the subduction zone was warm then. The coexistence of divergent (spreading ridge) and convergent (subduction zone) plate boundaries at which lithosphere is respectively generated and destroyed is the hallmark of plate tectonics. Here, we document temporally- and spatially-associated Neoarchean (2.55-2.51 Ga) rock assemblages with mid-ocean ridge and supra-subduction-zone origins from the Angou Complex, southern North China Craton. These assemblages record seafloor spreading and contemporaneous subduction initiation and mature arc magmatism, respectively, analogous to modern divergent and convergent plate boundary processes. Our results provide direct evidence for lateral plate motions in the late Neoarchean, and arguably the operation of plate tectonics, albeit with warmer than average Phanerozoic subduction geotherms. Further, we surmise that plate tectonic processes played an important role in shaping Earth's surficial environments during the Neoarchean and Paleoproterozoic.

Automated summary

This study provides new evidence for plate tectonics 2.55-2.51 billion years ago by reporting the coexistence of Neoarchean divergent and convergent plate boundary rock assemblages. The findings suggest that the subduction zone during that time was warmer than average. The results also indicate lateral plate motions in the late Neoarchean and the possible operation of plate tectonics, albeit with higher subduction geotherms than in the Phanerozoic. Plate tectonic processes likely played an important role in shaping Earth's surficial environments during the Neoarchean and Paleoproterozoic.