Oxygen isotope evidence for short-lived high-temperature fluid flow in the lower oceanic crust at fast-spreading ridges

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Abstract

Millimeter-scale amphibole veins in the lower oceanic crust record fracture-controlled fluid flow at high-temperatures but the importance of this fluid flow for the thermal and chemical evolution of the lower oceanic crust is unclear. In the section of lower oceanic crust recovered at Hess Deep from ODP Hole 894G, which formed at the fast-spreading East Pacific Rise, these veins are randomly distributed with an average spacing of similar to 1 m. We unravel the history of fluid flow through one of these veins by combining in situ O-isotope analyses of wall-rock plagioclase with major element analyses, geothermometry and diffusion modeling. Thermometry indicates vein sealing by amphibole at similar to 720 degrees C over a narrow temperature interval (+/- 20 degrees C). In situ O-isotope analyses by ion microprobe, with a precision of

Original languageEnglish
Pages (from-to)524-536
Number of pages13
JournalEarth and Planetary Science Letters
Volume260
Issue number3-4
DOIs
Publication statusPublished - 30 Aug 2007

Keywords

  • oceanic crust
  • hydrothermal circulation
  • O-isotope
  • diffusion
  • Hess Deep
  • EAST PACIFIC RISE
  • HESS-DEEP
  • HYDROTHERMAL CIRCULATION
  • SAMAIL OPHIOLITE
  • OMAN OPHIOLITE
  • ION MICROPROBE
  • DIFFUSION
  • FRACTIONATION
  • AMPHIBOLES
  • MINERALS

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