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Petrogenesis of lava from Christmas Island, Northeast Indian Ocean: implications for the nature of recycled components in non-plume intraplate settings

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Falloon, TJ ORCID: 0000-0001-6528-9739, Hoernle, K, Schaefer, BF, Bindeman, IN, Hart, SR, Garbe-Schonberg, D and Duncan, RA 2022 , 'Petrogenesis of lava from Christmas Island, Northeast Indian Ocean: implications for the nature of recycled components in non-plume intraplate settings' , Geosciences, vol. 12, no. 3 , pp. 1-37 , doi: 10.3390/geosciences12030118.

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Abstract

Lava samples from the Christmas Island Seamount Province (CHRISP) record an extreme range in enriched mantle (EM) type Sr-Nd-Pb-Hf isotope signatures. Here we report osmium isotope data obtained on four samples from the youngest, Pliocene petit-spot phase (Upper Volcanic Series, UVS; ~4.4 Ma), and four samples from the earlier, Eocene (Lower Volcanic Series, LVS; ~40 Ma) shield building phase of Christmas Island. Osmium concentrations are low (582 ppt) with initial Os isotopic values (187Os/188Osi) ranging from (0.12300.1679). Along with additional new geochemical data (major and trace elements, Sr-Nd-Pb isotopes, olivine δ18O values), we demonstrate the following: (1) The UVS is consistent with melting of shallow Indian mid-ocean ridge basalt (MORB) mantle enriched with both lower continental crust (LCC) and subcontinental lithospheric mantle (SCLM) components; and (2) The LVS is consistent with recycling of SCLM components related to Gondwana break-up. The SCLM component has FOZO or HIMU like characteristics. One of the LVS samples has less radiogenic Os (γOs 3.4) and provides evidence for the presence of ancient SCLM in the source. The geochemistry of the Christmas Island lava series supports the idea that continental breakup causes shallow recycling of lithospheric and lower crustal components into the ambient MORB mantle.

Item Type: Article
Authors/Creators:Falloon, TJ and Hoernle, K and Schaefer, BF and Bindeman, IN and Hart, SR and Garbe-Schonberg, D and Duncan, RA
Keywords: osmium isotopes, petit-spot volcanism, olivine oxygen isotopes, intraplate volcanism, Christmas Island, Indian Ocean, CHRISP, crust recycling, lithosphere recycling, DUPAL
Journal or Publication Title: Geosciences
Publisher: MDPI AG
ISSN: 2076-3263
DOI / ID Number: 10.3390/geosciences12030118
Copyright Information:

Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons 4.0 International (CC BY 4.0) license (https://creativecommons.org/licenses/by/4.0/).

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