It’s hydrogeology but not as we know it: Sub-seafloor groundwater flow driven by thermal gradients

¹ BGR, Hannover, Germany
² Helmholtz-Centre for Environmental Research GmbH – UFZ Leipzig, Department of Environmental Informatics, Leipzig, Germany
³ Technische Universität Dresden, Professorship of Contaminant Hydrology, Dresden, Germany
⁴ Leibniz Universität Hannover, Institute of Fluid Mechanics and Environmental Physics in Civil Engineering, Hannover, Germany

Contact Information: Vincent Post, Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany, Phone: +49-511-6432393, Email: vincent.post@bgr.de

Abstract

Groundwater flow beneath the oceans plays an important role for cooling the earth’s crust and geochemical cycles, yet it remains an understudied subject in hydrogeology. This contribution focuses on the circulation of seawater through basalt covered by deep-sea sediments in the equatorial northeast Pacific Ocean. Numerical model simulations are used to infer the factors controlling the flow patterns that develop between basalt outcrops. The energy to drive the flow is derived from the crustal heat flux. It is found that the sediment thickness plays a key role in determining the development of hydrothermal siphons, i.e. the flow between two adjacent seamounts where one acts as a recharge point and the other as a discharge point for seawater. Amongst the various factors tested, the outcrop width was an important factor as well.