UC Santa Cruz

Ridge-flank hydrothermal circulation is a critical crustal process that affects the Earth's global heat budget, geochemical signature of the Earth's oceans, and supports a vast and diverse subsurface biosphere. These hydrothermal systems are globally pervasive, found in ocean crust of varying ages, spreading rates, and depths. In addition to the broad spatial and structural occurrence, ridge-flank hydrothermal systems operate on a wide range of temperatures, some barely above the temperature of bottom sea water and others near boiling. This dissertation focuses on North Pond, an important end-member, ridge-flank, cool hydrothermal system located on slow-spreading crust in the North Atlantic Ocean. Here I present three original studies that elucidate hydrogeologic and thermal characteristics of North Pond. In chapter 1, I present the first coupled three-dimensional simulations of fluid and heat below North Pond revising many long-standing hypotheses in this system. In chapter 2, I extend three-dimensional simulations to incorporate anisotropic permeability representing important crustal processes and provide a more holistic approach to characterizing the hydrogeologic and thermal regimes of North Pond. Finally, in chapter 3, I develop a workflow for constructing geologically realistic simulation domains and provide insights and rationale about important considerations during this process. The combination of these studies sheds light on the hydrogeological and thermal regime of this non-discharge dominated, end-member system and provides insights into the drivers of hydrological and thermal processes that are important across the spectrum of ridge-flank hydrothermal systems.