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From ridge to subduction zone: dual-temperature serpentinization of the ophiolitic mantle revealed by triple oxygen isotopes and magnetite formation
File(s)
Author(s)
Qi, Liang
Wu, Guanghui
Muxworthy, AR
Cao, Xiaobin
Yang, Xiaokai
Type
Journal Article
Abstract
Mantle sections in ophiolites are almost always serpentinized. However, it often remains unclear whether the serpentinization occurs near the ridge axis during lithospheric formation, or later within the subduction zone during ophiolite obduction and emplacement. To constrain serpentinization in ophiolites, we combine triple-oxygen-isotope technique with rock magnetic and major-element analyses to establish an integrated framework linking fluid sources and temperatures to magnetite formation and iron behavior in serpentinite. We apply this framework to the Troodos ophiolite, Cyprus, where representative serpentinized samples were collected from ultramafic zones along a fossil ridge-transform intersection preserved within the ophiolite. Our analyses reveal fluid sources and distinct temperature regimes for ridge-axis and subduction mantle wedge serpentinization. Ridge-axis serpentinization is characterized by ~200-310 °C seawater circulation and strongly magnetic serpentinites, whereas mantle wedge serpentinization is associated with ~150-220 °C slab-derived fluids and weakly magnetic serpentinites. We further identify a temperature-dependent relationship linking serpentine iron content, magnetite formation
and magnetic properties. This relationship indicates the contrasting magnetic properties of serpentinite result from the preferential formation of magnetite over iron-rich serpentine at temperatures > 200-220 °C.
Date Issued
2026-09-09
Date Acceptance
2026-09-09
Citation
Geology, 2026
URI
ISSN
0091-7613
Publisher
Geological Society of America
Journal / Book Title
Geology
Copyright Statement
Copyright This paper is embargoed until publication. Once published the author’s accepted manuscript will be made available under a CC-BY License in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy).
License URL
Publication Status
Accepted