New isotopic evidence for the origin of Red Sea brines

Abstract

THE hot brines in the Atlantis II Deep in the Red Sea (Fig. 1) have concentrations of both oxygen- and hydrogen-isotopes which are different from those of the overlying Red Sea deep water but are identical to the surface waters, only at the southern parts of the Red Sea1,2. It was inferred, therefore, that these brines originated in the southern Red Sea and have migrated northwards to their present location. This hypothesis has often been questioned, using mainly geological arguments, the most striking of which is the improbability of a plumbing system which had to work over a distance of more than 800 km (refs 3, 4). However, the geochemical problem of the depletion in heavy isotopes in the hot brines as compared to the directly overlying seawater has still not been solved. We can add new data to this discussion from stable isotope analyses carried out on new brines which were found throughout the Red Sea (Fig. 1). Many of these occurrences are between the Atlantis II Deep and the southern Red Sea5.