Cross-hole tracer experiment reveals rapid fluid flow and low effective porosity in the upper oceanic crust

N. M. Neira, J. F. Clark, A. T. Fisher, C. G. Wheat, R. M. Haymon, Keir Becker

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Numerous field, laboratory, and modeling studies have explored the flows of fluid, heat, and solutes during seafloor hydrothermal circulation, but it has been challenging to determine transport rates and flow directions within natural systems. Here we present results from the first cross-hole tracer experiment in the upper oceanic crust, using four subseafloor borehole observatories equipped with autonomous samplers to track the transport of a dissolved tracer (sulfur hexafluoride, SF6) injected into a ridge-flank hydrothermal system. During the first three years after tracer injection, SF6 was transported both north and south through the basaltic aquifer. The observed tracer transport rate of ∼2–3 m/day is orders of magnitude greater than bulk rates of flow inferred from thermal and chemical observations and calculated with coupled fluid-heat flow simulations. Taken together, these results suggest that the effective porosity of the upper volcanic crust through which much tracer was transported is <1%, with fluid flowing rapidly along a few well-connected channels. This is consistent with the heterogeneous (layered, faulted, and/or fractured) nature of the volcanic upper oceanic crust.

Original languageEnglish (US)
Pages (from-to)355-365
Number of pages11
JournalEarth and Planetary Science Letters
Volume450
DOIs
StatePublished - Sep 15 2016

Fingerprint

upper crust
oceanic crust
fluid flow
tracers
Flow of fluids
crusts
Porosity
Sulfur Hexafluoride
tracer
porosity
Fluids
Flow simulation
Observatories
Boreholes
Aquifers
experiment
Experiments
volcanology
fluids
Heat transfer

Keywords

  • abyssal hills
  • borehole observatory
  • hydrothermal circulation
  • Juan de Fuca Ridge flank
  • ocean crustal properties
  • tracer injection experiment

ASJC Scopus subject areas

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

Cite this

Cross-hole tracer experiment reveals rapid fluid flow and low effective porosity in the upper oceanic crust. / Neira, N. M.; Clark, J. F.; Fisher, A. T.; Wheat, C. G.; Haymon, R. M.; Becker, Keir.

In: Earth and Planetary Science Letters, Vol. 450, 15.09.2016, p. 355-365.

Research output: Contribution to journalArticle

Neira, N. M. ; Clark, J. F. ; Fisher, A. T. ; Wheat, C. G. ; Haymon, R. M. ; Becker, Keir. / Cross-hole tracer experiment reveals rapid fluid flow and low effective porosity in the upper oceanic crust. In: Earth and Planetary Science Letters. 2016 ; Vol. 450. pp. 355-365.
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