Groundwater Flow and Geothermal Regime of Florida Plateau: ABSTRACT

The Three Scales of Submarine Groundwater Flow and Discharge across Passive Continental Margins

“…3), which may include multiple confined aquifer systems extending below the first confined aquifer to depths of 500 m or more below the seafloor and to the outer continental shelf edges, submarine canyon incisions, and even the continental slope, especially during sea-level lowstands. The primary process driving flow at this scale is usually geothermal convection, which produces seawater recirculation through the shelf (Kohout 1967;Wilson 2005;Hughes et al 2007Hughes et al , 2009. Sediment compaction and associated dewatering, as well as brine-related processes, are also important in some settings (Wilson and Ruppel 2007).…”

“…It could be argued that there is actually more known about the occurrence of submarine groundwater systems at the shelf scale, including relict reduced-salinity groundwater, than is known about intermediate embayment-scale submarine aquifer systems in some settings. This is mostly a result of ancillary data collected as part of offshore oil exploration as well as scientific drilling through the (Kohout 1966(Kohout , 1967Paull et al 1991) as well as drilling of the Atlantic Margin Coring (AMCOR) Project and Continental Offshore Stratigraphic Test (COST) Program wells in the 1970s (Hathaway et al 1979;Kohout 1988) and installation of submarine monitoring wells off New Jersey in 1985 (McAuley et al 2001). Shelfscale groundwater processes, including both development of pore fluid overpressure due to sediment compaction and submarine spring sapping, were long hypothesized to impact the geomorphology of the shelf edge, including initiating slope failures and contributing to submarine canyon formation (Johnson 1939;Robb 1984;Orange et al 1994).…”

Site 1004

“…This temperature difference causes the water in the platform interior to rise, causing water to enter through the sides of the platform. This mechanism has been described and documented in Florida and has been termed "Kohout convection" (Kohout, 1966(Kohout, , 1967. A second mechanism whereby fluids might be circulated through the platform results from the reflux of more saline waters derived on the surface of the Great Bahama Bank.…”

Introduction

“…A third possible mechanism, known as Kohout convection, postulates that cold water is circulated through the flanks of the platform and advected upward by the higher heat gradient within the platform relative to the adjacent oceans (Kohout, 1966(Kohout, , 1967. Simms (1984) concluded that such a flow should be present in all steep-sided platforms where there is a strong horizontal pore-water density gradient.…”