1874-2629/07 2007 Bentham Science Publishers Ltd. Numerical Modeling of Supercritical ‘Out-Salting ’ in the “Atlantis II Deep”

Abstract: Supercritical water behaves close to that of a non-polar fluid and its ability to dissolve salt ions is very low. In rifting locations world-wide, where hot vents occur, it has been shown that seawater attains supercritical conditions. We therefore anticipate that circulation of seawater in hydrothermal systems passing through regions of the supercritical do-main results in spontaneous precipitation of salt particles. Thus, the hot ‘geysers ’ of saturated brines observed in the ‘At-lantis II Deep ’ of the Red Sea could result from re-dissolution of salts accumulated in underground fracture systems. Here we report on an advanced numerical modeling study which demonstrates, for the first time, that there is a forced convec-tion cell where salts precipitate and accumulate. These combined numerical thermodynamic simulations and basin model-ling results also demonstrate that hot brines reflux back to surface immediately above the magma chamber located beneath the axis of the rift. Based on this study, we predict that hydrothermal ‘out-salting ’ is the main cause of dense, warm brines accumulating in the central portion of the Red Sea. Furthermore, the results are relevant for understanding how large vol-umes of evaporites (salts) accumulate along rifted plate margins