Submarine hydrogeology in volcanic seamount environments: An analysis of compaction- and buoyancy-driven fluid flow

Submarine fluid flow plays an important role in geothermal, geophysical, and geochemical processes within the oceanic crust. Seamounts and volcanic islands provide dynamic submarine environments in which to study hydrodynamics because both buoyancy- and compaction-driven flow interact due to the bathymetric relief and thick sedimentary aprons. I have developed a finite-element, transient, numerical code which couples fluid flow, heat transport, lithospheric flexure, sedimentation, and compaction to analyze the evolving hydrogeologic regime in these types of submarine environments.; There are four components in my dissertation: a theoretical analysis of the interactions between buoyancy- and compaction-driven flow, an examination of the evolution of fluid flow and pore pressure in the Hawaiian archipelago, a comparative analysis of fluid flow for three different volcanic seamounts, and a three-dimensional examination of fluid flow through seamounts. Compaction- and buoyancy-driven fluid flow are two major driving forces in submarine basins and the interactions between these two driving forces lead to complex flow patterns. Compaction can cause fluid to migrate unidirectionally across a marine basin instead of developing convection cells, thereby providing a mechanism for long distance mass transport. Compaction-driven flow can also help stimulate flow through the crust in areas of relatively low permeability. In the Hawaiian Islands, compaction-driven flow forces pore fluid from pelagic sediments below the edifice toward the flexural arch generating overpressures (pore pressure above hydrostatic). Similar processes are observed in the Marquesas and Canary Islands, however the thickness of prevolcanic sediment, sedimentation rate, and amount of lithospheric flexure influence the flow rates and patterns. By including the third dimension in our examination of submarine fluid flow, we observed that two-dimensional models generally underestimate the flow velocities and associated surface heat flux. Additionally, we quantified the amount that geometry and geology influence the fluid flow rates and patterns in seamount environments.; My dissertation gives the first detailed investigation of how compaction and convection are coupled in a submarine environment. By applying these results to seamount environments, we learn about flow pathways and pressure regimes of these areas, which may help explain geologic processes and may be applied to other submarine environments.