Plume-induced sinking of intracontinental lithospheric mantle: an overlooked mechanism of subduction initiation?

Cloetingh, S. et al. (2021) Plume-induced sinking of intracontinental lithospheric mantle: an overlooked mechanism of subduction initiation? Geochemistry, Geophysics, Geosystems, 22(2), e2020GC009. (doi: 10.1029/2020GC009482)

Abstract

Although many different mechanisms for subduction initiation have been proposed, only few of them are viable in terms of consistency with observations and reproducibility in numerical experiments. In particular, it has recently been demonstrated that intra-oceanic subduction triggered by an upwelling mantle plume could greatly contribute to the onset and operation of plate tectonics in the early and, to a lesser degree, modern Earth. On the contrary, the initiation of intra-continental subduction still remains underappreciated. Here we provide an overview of 1) observational evidence for upwelling of hot mantle material flanked by downgoing proto-slabs of sinking continental mantle lithosphere, and 2) previously published and new numerical models of plume-induced subduction initiation. Numerical modeling shows that under the condition of a sufficiently thick (>100 km) continental plate, incipient downthrusting at the level of the lowermost lithospheric mantle can be triggered by plume anomalies of moderate temperatures and without significant strain- and/or melt-related weakening of overlying rocks. This finding is in contrast with the requirements for plume-induced subduction initiation within oceanic or thinner continental lithosphere. As a result, plume-lithosphere interactions within continental interiors of Paleozoic-Proterozoic-(Archean) platforms are the least demanding (and thus potentially very common) mechanism for initiation of subduction-like foundering in the Phanerozoic Earth. Our findings are supported by a growing body of new geophysical data collected in various intra-continental areas. A better understanding of the role of intra-continental mantle downthrusting and foundering in global plate tectonics and, particularly, in the initiation of “classic” ocean-continent subduction will benefit from more detailed follow-up investigations.

• Item Type: Articles
• Additional Information: This study is co-funded by an Alexander von Humboldt Foundation fellowship to A. Koptev and A. Beniest; the Dis-tinguished Guest Scientist Fellowship Program of the Hungarian Academy of Sciences to S. Cloetingh; the MTA CSFK Lendület Pannon LitH2Oscope grant and NN128629 (Topo-Transylva-nia) grant to I. Kovács; and a German Science Foundation grant to T.A. Ehlers (DFG EH329 23-1).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Eizenhoefer, Dr Paul and Ehlers, Professor Todd A.
• Authors: Cloetingh, S., Koptev, A., Kovács, I., Gerya, T., Beniest, A., Willingshofer, E., Ehlers, T. A., Andrić-Tomašević, N., Botsyun, S., Eizenhöfer, P. R., François, T., and Beekman, F.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Geochemistry, Geophysics, Geosystems
• Publisher: Wiley
• ISSN: 1525-2027
• ISSN (Online): 1525-2027
• Published Online: 20 January 2021
• Copyright Holders: Copyright © 2020 The Author(s)
• First Published: First published in Geochemistry, Geophysics, Geosystems 22(2):e2020GC009482
• Publisher Policy: Reproduced under a creative commons licence

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