A new supercontinent self-destruct mechanism: evidence from the Late Triassic–Early Jurassic
We present a new conceptual model where supercontinents, by focusing subduction on narrow areas of the 670 km mantle discontinuity, trigger superplume events and initiate their own fragmentation. This supercontinent-triggered superplume mechanism for continental break-up is examined in light of the Mesozoic fragmentation of Pangaea–Gondwana. We summarize the evidence for a superplume event that occurred between 227 and 183 Ma ago, during the Late Triassic–Early Jurassic break-up of Pangaea–Gondwana. The evidence reviewed includes flood magmatism, kimberlite emplacement, plate reorganization and tectonism (including ophiolite obduction events), reversal rate frequency of the geomagnetic field, marine anoxia, deposition of carbon-rich sediments, including oil source rocks and coal, the carbon isotope record, major mass extinctions, and global sea levels. This Late Triassic–Early Jurassic superplume event was comparable in scale with those in the late Proterozoic (c. 800 Ma) and during Cretaceous times (c. 120–80 Ma). Similar to the mid-Cretaceous event, an extended phase of plume magmatism is implicated, with two oceanic and three continental large igneous provinces being emplaced.