Huang, Si-Fang, Wang, Wei, Kerr, Andrew C.  ORCID: https://orcid.org/0000-0001-5569-4730, Cawood, Peter A. and Lu, Guimei
2026.
Sediment melting during subduction initiation: Evidence of mantle-hosted S-type granitoids in the Neoproterozoic Fuchuan Ophiolite.
Global and Planetary Change
257
, 105272.
10.1016/j.gloplacha.2025.105272
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Abstract
The mechanisms and geodynamic significance of sediment recycling in subduction zones remain intensely controversial in Precambrian geology. This study reports a suite of Precambrian sediment-derived felsic intrusions preserved within an exhumed mantle peridotite of a supra-subduction zone in South China. These felsic rocks intruded into the peridotite of the Fuchuan Ophiolite show U-Pb ages of 846–837 Ma, coinciding with the dating of ca. 848–820 Ma crustal section rocks of the ophiolite, implying their generation during slab subduction rather than later obduction. Petrography, zircon O isotopic and trace elemental signatures of the Fuchuan mantle-hosted granitoids indicate S-type affinity. Integrated O (δ18O = 7.5 ‰ to 11.3 ‰), Hf (ɛHf(t) = −3.8 to +6.9) and Nd (ɛNd(t) = −2.2 to −0.4) isotopic compositions, coupled with inherited zircon ages and whole-rock geochemistry, collectively suggest derivation from a continental margin sediment protolith. Geochemical analyses and pseudosection modeling reveal partial melting of subducted sediment at 650–790 °C and < 4 kbar (∼12–15 km). This condition of melting is atypical in a mature subduction channel, but is plausible during the initiation phase of subduction. Consequently, the mantle-hosted S-type intrusions formed during slab subduction may represent a proxy for subduction initiation. In contrast to the formation depth (< 14 kbar; depths <45 km) of Phanerzoic mantle-hosted leucogranitoids, sediment-derived melt transport from subducting slabs during the Neoproterozoic occurred at substantially shallower depths, suggesting that the Neoproterozoic era may witness the reoperating of modern-style plate tectonics after Earth's middle age, occurring under elevated mantle potential temperatures relative to present-day conditions.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Schools > Earth and Environmental Sciences |
| Publisher: | Elsevier |
| ISSN: | 0921-8181 |
| Date of First Compliant Deposit: | 9 January 2026 |
| Date of Acceptance: | 22 December 2025 |
| Last Modified: | 09 Jan 2026 10:00 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/183737 |
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