Discovery of a heavy silicon isotope mantle reservoir

Liu, Mao-Rui, Wang, Jun, Cui, Ze-Xian, Wei, Gang-Jian, Yang, Qing, Xu, Yi-Gang, Kerr, Andrew C. ORCID: https://orcid.org/0000-0001-5569-4730, Wyman, Derek, Bai, Jiang-Hao, Zhu, Guan-Hong, Ma, Lin, Hao, Lu-Lu, Zhou, Jin-Sheng, Fan, Jing-Jing, Huang, Tong-Yu, Zhang, Miao-Yan and Wang, Qiang 2025. Discovery of a heavy silicon isotope mantle reservoir. National Science Review , nwaf410. 10.1093/nsr/nwaf410

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Abstract

Silicon cycling between Earth’s reservoirs provides critical insights into how the Earth operates. While average crust and the Bulk Silicate Earth (BSE) share similar silicon isotope (δ30Si) compositions, some mantle-derived magmas exhibit lower δ30Si values than the BSE, implying the existence of an unidentified mantle reservoir with complementary higher δ30Si values. We present silicon isotope data from Cenozoic lamproites and their hosted mantle pyroxenite xenoliths from the Himalaya-Tibet orogen. These mantle-derived rocks have higher δ30Si values than the BSE, which resulted from reaction between mantle peridotite and 30Si-rich silicate melts from subducted Indian continental crust. Our results demonstrate that slab melting can produce high-δ30Si melts and complementary low-δ30Si residues. These products are unevenly distributed in the mantle - with high-δ30Si melts stored as metasomatic veins in the lithospheric mantle while low-δ30Si residues are recycled into deep mantle. This study provides evidence that mantle metasomatism by high-δ30Si slab melts creates heavy silicon reservoirs in the lithospheric mantle above continental slabs or cool mantle wedges above oceanic slabs.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Computer Science & Informatics
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Start Date: 2025-09-24
Publisher:	Oxford University Press
ISSN:	2095-5138
Date of First Compliant Deposit:	8 October 2025
Last Modified:	08 Oct 2025 09:45
URI:	https://orca.cardiff.ac.uk/id/eprint/181550

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