Deep Meteoric Water Circulation in Earth's Crust

Abstract

Deep meteoric waters comprise a key component of the hydrologic cycle, transferring water, energy, and life between the Earth's surface and deeper crustal environments, yet little is known about the nature and extent of meteoric water circulation. Using water stable isotopes, we show that maximum circulation depths of meteoric waters across North America vary considerably from <1 to 5 km, with the deepest circulation in Western North America in areas of greater topographic relief. Shallower circulation occurs in sedimentary and shield‐type environments with subdued topography. The amount of topographic relief available to drive regional groundwater flow and flush saline fluids is an important control on the extent of meteoric water circulation, in addition to permeability. The presence of an active flow system in the upper few kilometers of the Earth's crust and stagnant brines trapped by negative buoyancy offers a new framework for understanding deep groundwater systems.

Eocene fault-controlled fluid flow and mineralization in the Paradox Basin, United States

“…Rapid erosional exhumation and incision can lead to the formation of high relief topography along with high hydraulic gradients, where we can expect deeper circulation of meteoric waters recharged at higher elevations (McIntosh and Ferguson, 2021). This process can sweep reduced, hydrocarbon-bearing fluids into shallower formations along discharge zones such as faults, a process possibly responsible for the flow of hydrocarbons in the Rainbow Rocks paleo-oil reservoir (cite).…”

Crustal Groundwater Volumes Greater Than Previously Thought

“…Based on circulation depths of meteoric water (McIntosh & Ferguson, 2021), salinity distributions (Ferguson, McIntosh, Grasby, et al, 2018;Ferguson, McIntosh, Perrone, & Jasechko, 2018;Fritz & Frape, 1982;Stanton et al, 2017) and groundwater residence times ranging from tens of thousands (Jasechko et al, 2017) to over a billion years (Holland et al, 2013;Warr et al, 2018), the ∼20 million km 3 of water beneath 1-2 km in both sedimentary and crystalline rock is only weakly connected to the rest of the hydrologic cycle. There is little evidence of water with these chemistries discharging to surface environments.…”

“…Mixing of shallow and deep groundwater during these events may have important implications to biogeochemical cycles and subsurface life (Head et al, 2003;Martini et al, 2003;Wilhelms et al, 2001 Finally, despite potentially being the largest continental store of water, groundwater generally receives less attention than other parts of the hydrologic cycle (Famiglietti, 2014). This is especially true of deep groundwater, which is hitherto largely uncharacterized (McIntosh & Ferguson, 2021;Stober & Bucher, 2007;Warr et al, 2018Warr et al, , 2021. Our knowledge of the deep hydrogeosphere is limited to a few deep drilling projects and windows provided by the oil and gas industry and deep mines.…”

“…Our knowledge of the deep hydrogeosphere is limited to a few deep drilling projects and windows provided by the oil and gas industry and deep mines. Increased efforts are required in this frontier area of hydrology to understand hydrologic (Ferguson, McIntosh, Grasby, et al, 2018;McIntosh & Ferguson, 2021;Warr et al, 2018) and geochemical cycles (Li et al, 2016;Sherwood Lollar et al, 2014) and the distribution of life in the subsurface (Bar-On et al, 2018;Lollar et al, 2019;Magnabosco et al, 2018). This will require consideration of modern hydrogeological conditions as well as those over geological time as far back as the oldest crustal rocks (Precambrian Era in some cases).…”

“…Gleeson et al (2016) estimated that 22.6 million km 3 of groundwater was present in the upper 2 km of the Earth's crust (Table1; Figure 1). Although the volume of groundwater above the 2 km boundary includes most potable groundwater resources, the circulation of meteoric water can extend well beyond this depth (McIntosh & Ferguson, 2021). Groundwater flow is known to occur to a depth of at least 10 km based on evidence from geological processes, such as metamorphism , hydrothermal activity (Ingebritsen et al, 1992), and seismicity (Townend & Zoback, 2000).…”