U.S. Dept. of Commerce / NOAA / OAR / ERL / PMEL /
Publications
Seafloor eruptions and evolution of hydrothermal fluid
chemistry
Butterfield, D.A., I.R. Jonasson, G.J. Massoth, R.A. Feely,
K.K. Roe, R.E. Embley, J.F. Holden, R.E. McDuff, M.D. Lilley, and
J.R. Delaney
Philosophical Transactions of the Royal Society of London
A, 355, 369-386 (1997)
A major challenge confronting geochemists is to relate the
chemistry of vented hydrothermal fluids to the local or regional
tectonic and volcanic state of mid-ocean ridges. After more than
15 years of sampling submarine hydrothermal fluids, a complex
picture of spatial and temporal variability in temperature and
composition is emerging. Recent time-series observations and
sampling of ridge segments with confirmed recent volcanic
eruptions (CoAxial and North Cleft on the Juan de Fuca ridge and
9-10°N on the East Pacific Rise) have created a first-order
understanding of how hydrothermal systems respond to volcanic
events on the seafloor. Phase separation and enhanced volatile
fluxes are associated with volcanic eruptions, with
vapor-dominated fluids predominating in the initial post-eruption
period, followed in time by brine-dominated fluids, consistent
with temporary storage of brine below the seafloor. Chemical data
for CoAxial vents presented here are consistent with this
evolution. Rapid changes in output and composition of
hydrothermal fluids following volcanic events may have a profound
effect on microbiological production, macrofaunal colonization,
and hydrothermal heat and mass fluxes. Size and location of the
heat source are critical in determining how fast heat is removed
and whether sub-seafloor microbial production will flourish.
CoAxial event plumes may be a direct result of dyking and
eruption of lavas on the seafloor.
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