Prolonged super-orogens during Gondwana assembly contributed to the formation of a habitable Earth: Insights from big data

Abstract

Since the initiation of plate tectonics on Earth, the evolution of tectonic regime and supercontinent cycles (Nuna, Rodinia and Pangea) have been the first order factors that contributed to Earth surficial environmental changes and thus development of Earth habitability. In particular, the Neoproterozoic to Cambrian eras recorded dramatic evolution in solid earth and surficial systems, including the breakup of the Rodinia supercontinent and the assembly of the Gondwana (680–430 Ma) landmasses, the Neoproterozoic Oxidation Event (NOE) and Cambrian life diversification. However, the key tectonic factors that were responsible for the evolution of Earth surficial systems during this period remain highly debated and are largely confined to conceptual models. The authors reconstructed the temporal trends of continental orogenic belts, using detrital zircon europium anomalies (Eu/Eu*) and orogen length big data database. The quantitative results indicate that the sustained orogens over 200 Ma formed prolonged super-mountains during the Gondwana assembly period. This might have occurred due to the initiation of modern type plate tectonic regime since the Neoproterozoic time, which allowed large-scale continental deep-subduction for the first time in Earth history. This coincides well with the large-scale Himalaya type collision orogenic belt during Gondwana assembly, along with the sudden drops of the global thermobaric ratio (T/P) and the large-scale occurrence of high-pressure and ultrahigh-pressure metamorphism. This suggests that orogenic elevation and scales were comparable to those of modern Earth. The high topographic relief of terrestrial systems during this time likely resulted in intense weathering and erosion of low-latitude orogenic belts, supplying huge continental sediments to the ocean, consistent with the seawater Sr isotope variation. Huge sediments and nutrients supply profoundly changed ocean composition and increased ocean productivity, triggering Neoproterozoic oxygenation events and providing environmental triggers for the Ediacaran–Cambrian explosion. Overall, multiple factors, with orogens being the most important one, contributed to the genetic, environmental and ecological conditions for Ediacaran life radiation and Cambrian life explosion.