EGU2020-12348 https://doi.org/10.5194/egusphere-egu2020-12348 EGU General Assembly 2020 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.
From Rodinia to Pangea: an extroversion process driven first by plume push followed by downwelling pull, absorption and merging
Numerous works also suggested that mantle plumes or mantle upwellings associated with LLSVPs in a degree-2 mantle state play a major role in driving the break-up of a supercontinent. However, subduction and mantle downwelling may play an increasing role in the leadup to the assembly of the next supercontinent. Anderson (1994) noticed that continents tend to gather at mantle downwelling zones, which was later developed into the hypothesis of orthoversion assembly of supercontinents by Mitchell (2012). Zhong et al. (2007) conceptualised the assembly of supercontinents through the merger or absorption of mantle downwellings, leading to the assembly of supercontinents over a superdownwelling in a degree-1 mantle. Here we present a revised global paleogeographic reconstruction featuring an extroversion assembly of Pangea (i.e. through the closure of the Mirovoi superocean) over a pre-existing yet dynamic mantle downwelling zone (Li et al., 2019). In particular, we show that the Paleozoic world was dominated by two major subduction (dowelling) cells, one associated with the newly assembled Gondwana, and the other associated with the assembly of Laurasia. The two cells gradually merged together by the Carboniferous time, forming the supercontinent Pangea over a mantle superdownwelling (Zhang et al., 2010). It was during the merger of the two dowelling cells that continental and arc terranes was successively transported from Gondwana margin to future Laurasia.
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