Extension of a WHOI-DOEI Postdoctoral Scholar Project: Sub-surface flow dynamics and poroelastic behavior in hydrothermal systems

Thibaut Barreyre, Geology & Geophysics
Dan Fornari, Geology & Geophysics

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2015 OEI Funded Project

Summary

We propose to develop a rigorous method for exploiting the tidal variability observed in exit-fluid temperature records as a means to constrain the crustal permeability structure of deep-sea vent fields (i.e., Lucky Strike, East Pacific Rise – 9°50’N, Main Endeavour Field and Lau Basin Field).
 
This work is motivated by the fact that permeability is a master variable that controls both the intensity and geometry of sub-surface convection. Despite its importance, permeability is also the most poorly constrained hydrologic parameter for oceanic crust, with constraints derived from various methodologies spanning several orders of magnitude. In order to make progress towards to the goal of understanding subsurface flow it will be necessary to develop novel methods that can robustly constrain key parameters as permeability without requiring major infrastructure investments, and this provides the overarching motivation for our proposed research – to use the natural forcing from ocean tides to constrain the permeability structure of deep-sea hydrothermal fields.
 
Using new high-resolution data along with our compiled dataset we extend the analytical models of poroelastic response to include multi-layer geometries and multi-phase flow, and we synthesize our results in order to understand how tidal loading affects hydrothermal flow in geologically distinct MOR settings (e.g., spreading rate/crustal structure, volcanic/tectonic activity) subject to a range of tidal loading amplitudes.
 
We propose to accomplish both of these tasks as part of a post-doctoral research program for Barreyre, with mentoring and support from Fornari.