Depletion of the upper mantle by convergent tectonics in the Early Earth

Abstract Partial melting of mantle peridotites at spreading ridges is a continuous global process that forms the oceanic crust and refractory, positively buoyant residues (melt-depleted mantle peridotites). In the modern Earth, these rocks enter subduction zones as part of the oceanic lithosphere. H...

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Autores principales:	A. L. Perchuk, T. V. Gerya, V. S. Zakharov, W. L. Griffin
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/a042816e5bdc40dfb20898a07e572ccd
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spelling	oai:doaj.org-article:a042816e5bdc40dfb20898a07e572ccd2021-11-08T10:56:07ZDepletion of the upper mantle by convergent tectonics in the Early Earth10.1038/s41598-021-00837-y2045-2322https://doaj.org/article/a042816e5bdc40dfb20898a07e572ccd2021-11-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-00837-yhttps://doaj.org/toc/2045-2322Abstract Partial melting of mantle peridotites at spreading ridges is a continuous global process that forms the oceanic crust and refractory, positively buoyant residues (melt-depleted mantle peridotites). In the modern Earth, these rocks enter subduction zones as part of the oceanic lithosphere. However, in the early Earth, the melt-depleted peridotites were 2–3 times more voluminous and their role in controlling subduction regimes and the composition of the upper mantle remains poorly constrained. Here, we investigate styles of lithospheric tectonics, and related dynamics of the depleted mantle, using 2-D geodynamic models of converging oceanic plates over the range of mantle potential temperatures (Tp = 1300–1550 °C, ∆T = T − Tmodern = 0–250 °C) from the Archean to the present. Numerical modeling using prescribed plate convergence rates reveals that oceanic subduction can operate over this whole range of temperatures but changes from a two-sided regime at ∆T = 250 °C to one-sided at lower mantle temperatures. Two-sided subduction creates V-shaped accretionary terrains up to 180 km thick, composed mainly of highly hydrated metabasic rocks of the subducted oceanic crust, decoupled from the mantle. Partial melting of the metabasic rocks and related formation of sodic granitoids (Tonalite–Trondhjemite–Granodiorite suites, TTGs) does not occur until subduction ceases. In contrast, one sided-subduction leads to volcanic arcs with or without back-arc basins. Both subduction regimes produce over-thickened depleted upper mantle that cannot subduct and thus delaminates from the slab and accumulates under the oceanic lithosphere. The higher the mantle temperature, the larger the volume of depleted peridotites stored in the upper mantle. Extrapolation of the modeling results reveals that oceanic plate convergence at ∆T = 200–250 °C might create depleted peridotites (melt extraction of > 20%) constituting more than half of the upper mantle over relatively short geological times (~ 100–200 million years). This contrasts with the modeling results at modern mantle temperatures, where the amount of depleted peridotites in the upper mantle does not increase significantly with time. We therefore suggest that the bulk chemical composition of upper mantle in the Archean was much more depleted than the present mantle, which is consistent with the composition of the most ancient lithospheric mantle preserved in cratonic keels.A. L. PerchukT. V. GeryaV. S. ZakharovW. L. GriffinNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q A. L. Perchuk T. V. Gerya V. S. Zakharov W. L. Griffin Depletion of the upper mantle by convergent tectonics in the Early Earth
description	Abstract Partial melting of mantle peridotites at spreading ridges is a continuous global process that forms the oceanic crust and refractory, positively buoyant residues (melt-depleted mantle peridotites). In the modern Earth, these rocks enter subduction zones as part of the oceanic lithosphere. However, in the early Earth, the melt-depleted peridotites were 2–3 times more voluminous and their role in controlling subduction regimes and the composition of the upper mantle remains poorly constrained. Here, we investigate styles of lithospheric tectonics, and related dynamics of the depleted mantle, using 2-D geodynamic models of converging oceanic plates over the range of mantle potential temperatures (Tp = 1300–1550 °C, ∆T = T − Tmodern = 0–250 °C) from the Archean to the present. Numerical modeling using prescribed plate convergence rates reveals that oceanic subduction can operate over this whole range of temperatures but changes from a two-sided regime at ∆T = 250 °C to one-sided at lower mantle temperatures. Two-sided subduction creates V-shaped accretionary terrains up to 180 km thick, composed mainly of highly hydrated metabasic rocks of the subducted oceanic crust, decoupled from the mantle. Partial melting of the metabasic rocks and related formation of sodic granitoids (Tonalite–Trondhjemite–Granodiorite suites, TTGs) does not occur until subduction ceases. In contrast, one sided-subduction leads to volcanic arcs with or without back-arc basins. Both subduction regimes produce over-thickened depleted upper mantle that cannot subduct and thus delaminates from the slab and accumulates under the oceanic lithosphere. The higher the mantle temperature, the larger the volume of depleted peridotites stored in the upper mantle. Extrapolation of the modeling results reveals that oceanic plate convergence at ∆T = 200–250 °C might create depleted peridotites (melt extraction of > 20%) constituting more than half of the upper mantle over relatively short geological times (~ 100–200 million years). This contrasts with the modeling results at modern mantle temperatures, where the amount of depleted peridotites in the upper mantle does not increase significantly with time. We therefore suggest that the bulk chemical composition of upper mantle in the Archean was much more depleted than the present mantle, which is consistent with the composition of the most ancient lithospheric mantle preserved in cratonic keels.
format	article
author	A. L. Perchuk T. V. Gerya V. S. Zakharov W. L. Griffin
author_facet	A. L. Perchuk T. V. Gerya V. S. Zakharov W. L. Griffin
author_sort	A. L. Perchuk
title	Depletion of the upper mantle by convergent tectonics in the Early Earth
title_short	Depletion of the upper mantle by convergent tectonics in the Early Earth
title_full	Depletion of the upper mantle by convergent tectonics in the Early Earth
title_fullStr	Depletion of the upper mantle by convergent tectonics in the Early Earth
title_full_unstemmed	Depletion of the upper mantle by convergent tectonics in the Early Earth
title_sort	depletion of the upper mantle by convergent tectonics in the early earth
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/a042816e5bdc40dfb20898a07e572ccd
work_keys_str_mv	AT alperchuk depletionoftheuppermantlebyconvergenttectonicsintheearlyearth AT tvgerya depletionoftheuppermantlebyconvergenttectonicsintheearlyearth AT vszakharov depletionoftheuppermantlebyconvergenttectonicsintheearlyearth AT wlgriffin depletionoftheuppermantlebyconvergenttectonicsintheearlyearth
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Depletion of the upper mantle by convergent tectonics in the Early Earth

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