From ocean to mantle: new evidence for U-cycling with implications for the HIMU source and the secular Pb isotope evolution of Earth's mantle

Pettke, Thomas; Kodolányi, János; Kamber, Balz S. (2018). From ocean to mantle: new evidence for U-cycling with implications for the HIMU source and the secular Pb isotope evolution of Earth's mantle. Lithos, 316-317, pp. 66-76. Elsevier 10.1016/j.lithos.2018.07.010

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Of the isotopically distinctive mantle domains, the so-called HIMU (“high-μ”; μ=238U/204Pb) source is the most extreme, and its genesis continues to be debated. We report very strong U enrichment at unchanged Th concentrations
in Cretaceous oceanic serpentinites with exceptionally high 206Pb/204Pb (reaching 56) but unchanged 208Pb/204Pb. Similar, but less extreme, features are found in 1.9 billion years old altered oceanic crust (AOC). Forward modelling demonstrates that mantle, if metasomatised by supercritical liquids derived from AOC and serpentinites, evolves to the HIMUPb isotope signatures,while satisfying experimental and empirical constraints on subduction zone element processing. By contrast, no model solutions for the conventional proposal of the HIMU source representing residual igneous altered oceanic crust can be reconciledwith 208Pb/204Pb, strengthening the need for a paradigm shift regarding HIMU OIB genesis. Over time, the net U addition to the convecting mantle via deeply subducted serpentinite has expressed itself as the so-called second terrestrial Pb isotope paradox,or kappa conundrum.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Rock-Water Interaction

UniBE Contributor:

Pettke, Thomas and Kodolányi, János

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0024-4937

Publisher:

Elsevier

Funders:

[4] Swiss National Science Foundation

Language:

English

Submitter:

Thomas Pettke

Date Deposited:

23 Nov 2018 10:32

Last Modified:

13 Mar 2021 17:16

Publisher DOI:

10.1016/j.lithos.2018.07.010

BORIS DOI:

10.7892/boris.121220

URI:

https://boris.unibe.ch/id/eprint/121220

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