THE DEVELOPMENT OF LAYERING, FLUXES THROUGH DOUBLE-DIFFUSIVE INTERFACES, AND LOCATION OF HYDROTHERMAL SOURCES OF BRINES IN THE ATLANTIS-II-DEEP - RED-SEA

The brines in the Atlantis II Deep of the Red Sea occur in horizontall y uniform, well-mixed layers, with the hottest and saltiest water at t he bottom, separated from the successively cooler and fresher layers a bove by very sharp vertical temperature and salinity gradients, Data a cccumulated over 3 decades are used to test the widely accepted hypoth esis that all heat and salt for the brine layers are supplied from bel ow and that the layered brine structure is the result of double diffus ion. Using the changes in temperature and salinity in each layer over successive time intervals, one can deduce the corresponding fluxes of heat and salt across the interfaces. It is found that the required flu x of salt cannot be sustained by double diffusion alone. An alternativ e calculation shows that most of the salt in the successively forming upper layers must have been injected directly from the bottom of the d eep through one or more vents located above the level of the lowest br ine interface, For the bottom layer, however, it is not possible to ob tain the observed salinity and temperature changes unless hot saline w ater is injected directly into that layer and some of the heat and a s maller fraction of the salt are transferred upward through the interfa ce. This process will also maintain convection in each of the layers a nd keep them well mixed, as is observed. The new interpretation in ter ms of separate inputs at various levels in the Atlantis II Deep is als o supported by recent geochemical evidence.