<<

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 to Pangea: an extroversion process driven first by plume push followed by downwelling pull, absorption and merging

Zheng-Xiang Li, William Collins, Lei Wu, and Sergei Pisarevsky Curtin University, Dynamics Research Group, School of Earth and Planetary Sciences, Perth, ([email protected])

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 . However, subduction and mantle downwelling may play an increasing role in the leadup to the assembly of the next supercontinent. Anderson (1994) noticed that tend to gather at mantle downwelling zones, which was later developed into the hypothesis of orthoversion assembly of 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 ) over a pre-existing yet dynamic mantle downwelling zone (Li et al., 2019). In particular, we show that the was dominated by two major subduction (dowelling) cells, one associated with the newly assembled , and the other associated with the assembly of . The two cells gradually merged together by the 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 was successively transported from Gondwana margin to future Laurasia.

References:

Anderson, D.L., 1994. Superplume or supercontinents? Geology 22, 39-42.

Huang, C., Zhang, N., Li, Z.-X., Ding, M., Dang, Z., Pourteau, A., Zhong, S., 2019. Modeling the Inception of Supercontinent Breakup: Stress State and the Importance of Orogens. Geochemistry, Geophysics, Geosystems 20, 4830-4848.

Li, Z.X., Mitchell, R.N., Spencer, C.J., Ernst, R., Pisarevsky, S., Kirscher, U., Murphy, J.B., 2019. Decoding Earth’s rhythms: Modulation of supercontinent cycles by longer superocean episodes. Research 323, 1-5.

Mitchell, R.N., Kilian, T.M., Evans, D.A.D., 2012. Supercontinent cycles and the calculation of absolute palaeolongitude in deep time. 482, 208-211.

Zhang, N., Zhong, S., Leng, W., Li, Z.-X., 2010. A model for the of the Earth's mantle structure since the Early Paleozoic. Journal of Geophysical Research: Solid Earth 115, B06401.

Zhong, S., Zhang, N., Li, Z.-X., Roberts, J.H., 2007. Supercontinent cycles, true polar wander, and very long-wavelength mantle convection. Earth and Planetary Science Letters 261, 551-564.

Powered by TCPDF (www.tcpdf.org)