Global distribution of the HIMU end member: Formation through Archean plume-lid tectonics.

Homrighausen, Stephan, Hoernle, Kaj , Hauff, Folkmar , Geldmacher, Jörg , Wartho, Jo-Anne , van den Bogaard, Paul and Garbe-Schönberg, Dieter (2018) Global distribution of the HIMU end member: Formation through Archean plume-lid tectonics. Open Access Earth-Science Reviews, 182 . pp. 85-101. DOI 10.1016/j.earscirev.2018.04.009.

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Oceanic basalts reflect the heterogeneities in the earth's mantle, which can be explained by five mantle end members. The HIMU end member, characterized by high time-integrated μ (238U/204Pb), is defined by the composition of lavas from the ocean islands of St. Helena, South Atlantic Ocean and Mangaia and Tubuai (Cook-Austral Islands), South Pacific Ocean. It is widely considered to be derived from a mantle reservoir that is rarely sampled and not generally involved in mixing with the other mantle components. On the other hand, the FOZO end member, located at the FOcal ZOne of oceanic volcanic rock arrays on isotope diagrams, is considered to be a widespread common component with slightly less radiogenic 206Pb/204Pb and intermediate Sr-Nd-Hf isotopic compositions. Here we present new major and trace element, Sr-Nd-Pb-Hf isotope and geochronological data from the Walvis Ridge and Richardson Seamount in the South Atlantic Ocean and the Manihiki Plateau and Eastern Chatham Rise in the southwest Pacific Ocean. Our new data, combined with literature data, document a more widespread (nearly global) distribution of the HIMU end member than previously postulated. Our survey shows that HIMU is generally associated with low-volume alkaline, carbonatitic and/or kimberlitic intraplate volcanism, consistent with derivation from low degrees of melting of CO2-rich sources. The majority of end member HIMU locations can be directly related to hotspot settings. The restricted trace element and isotopic composition (St. Helena type HIMU), but near-global distribution, point to a deep-seated, widespread reservoir, which most likely formed in the Archean. In this context we re-evaluate the origin of a widespread HIMU reservoir in an Archean geodynamic setting. We point out that the classic ocean crust recycling model cannot be applied in a plume-lid dominated tectonic setting, and instead propose that delamination of carbonatite- metasomatized subcontinental lithospheric mantle could be a suitable HIMU source.

Document Type: Article
Keywords: HIMU; FOZO; Walvis ridge; Chatham rise; Manihiki plateau; Shona hotspot
Research affiliation: Kiel University
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.earscirev.2018.04.009
ISSN: 0012-8252
Date Deposited: 08 May 2018 06:53
Last Modified: 03 May 2020 23:38

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