From tectonic-environmental factors of Early life diversification during Gondwana assembly to Earth Science System

The Cambrian animal diversification is a milestone in life evolution history. This also coincides well the Neoproterozoic atmospheric oxygenation (NOE), Gondwana assembly (~680~430 Ma) and Snowball Earth event, as well as magnetic field extreme evolution and formation of Earth inner core. Moreover, modern plate tectonics may have also been established during this period. Thus, solid Earth and surficial system evolution must be closely linked. However, the tectonic factors that drove the evolution of surficial systems during Gondwana assembly are less constrained, as is the driving mechanism. Most earlier studies are limited to conceptual models. Here, a review of data patterns shows that this period initiated with the breakup of the Rodinia supercontinent, whic’h induced the Snowball Earth and oxygenation events. The subsequent Gondwana assembly, within the modern plate tectonic regime, generated super-orogens that lasted for more than 200 million years. The elevations of these over 9000 km long super orogens might have been comparable to those of modern Earth, which should have served as a continuous driving force for the Earth’s surficial environs. The large-scale Himalaya type collision orogenic belt during this period is consistent with the sudden drops of the global thermobaric ratio (T/P) and the large-scale occurrence of high-pressure and ultrahigh-pressure metamorphism. On the other hand, due to secular mantle cooling and thinning of the oceanic crust, the duality of ocean and continental crust became more significant at this time. This indicates that the topographic relief might have reached an unprecedented level during this period, which can provide ecological space for ocean animal system. This, together with low-latitude orogenic belts caused extensive weathering and supplied a huge amount of continental sediments to the ocean, consist with the seawater Sr isotope that reached the highest value in the history. Meanwhile, snowball Earth also contributed to continental weathering. Huge sediments and nutrients supply profoundly changed ocean composition and increased ocean productivity, triggering oxygenation events. In addition, in the late Neoproterozoic to the Cambrian time, the Earth had an extremely weak magnetic field, possibly related to the formation of the Earth’s inner core. Ediacaran true polar wander path and high frequency magnetic field reversing also occurred. This indicates high cosmic radiation that might have contributed to genetic mutation. Therefore, multiple accidental and inevitable factors provided genetic, environmental and ecological conditions for Ediacaran life radiation and Cambrian life explosion. In addition, the increased supply of sediments reduced the friction coefficient within subduction zone and increases the plate subduction rate, which can explain the rapid continental plate drift during Gondwana cycle Overall, the Gondwana cycle is a critical period in the evolution of the Earth system.