Abstract

Active reflux may occur during periods of platform-top brine generation, but the role and fate of these brines after reflux events are uncertain. We have used a numerical flow model to investigate and quantify the response of reflux brines to changes in platform-top salinity. Simulations suggest that reflux brines, originally concentrated to gypsum saturation (150‰), have a relatively long platform residence time, on the order of 100 times the duration of the reflux event. When brine-generating conditions cease, brines will continue to sink through the platform, entraining seawater, a variant of reflux circulation we term latent reflux. Mesosaline brines intercepted by drilling of carbonate margins by the Ocean Drilling Program may have originated from Pleistocene reflux event(s) on the adjacent platform top and be currently moving by latent reflux. Latent-reflux circulation could deliver a significant quantity of dissolved reactants to platform carbonates, including Mg for dolomitization.

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