Post-obduction listwaenite genesis in the Oman Mountains inferred from structural analysis and U-Pb carbonate dating

Andreas Scharf*, Christopher M. Bailey, Robert Bolhar, Frank Mattern, Uwe Ring

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Listwaenite, a distinctive rock formed by carbonation of peridotite, is important for understanding carbon fluxes and storage in the deep Earth. In northern Oman, this lithology occurs near/at the base of the Semail Ophiolite and has been proposed to have formed in the mantle wedge during Late Cretaceous obduction and ophiolite emplacement. Listwaenite occurs as tabular sheets associated with post-obductional extensional faults. Specifically, listwaenite formed in (1) extensional duplexes bound by shallowly-dipping normal faults, (2) moderately- to steeply-dipping extensional faults, and (3) layers that overlie rocks of the metamorphic sole and unmetamorphosed platform carbonates. Two dolomite veins cutting listwaenite yield near-identical LA-ICP-MS U-Pb ages of 60.3 ± 15.4 and 55.1 ± 4.7 Ma (2 standard error). Thus, listwaenite formed prior to or is coeval with the ∼60-55 Ma veins. One carbonate listwaenite sample yields a LA-ICP-MS U-Pb age of 64.31 ± 6.28 Ma. Further six listwaenite samples yield imprecise ages of ∼33-3 Ma. Thus, listwaenite is interpreted to have formed during at least two post-obductional deformational events in the Oman Mountains. Hydrothermal circulation of carbon-rich fluids along upper crustal extensional faults facilitated listwaenite formation. Our results indicate that listwaenite formed during post-obductional extension, challenging models of listwaenite genesis in the mantle wedge during obduction.

Original languageEnglish
Article number117756
JournalEarth and Planetary Science Letters
Volume595
DOIs
Publication statusPublished - Oct 1 2022
Externally publishedYes

Keywords

  • carbonated and silicified ultramafics
  • CO sink
  • doming
  • extension
  • subduction

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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