A REVIEW OF SOME ASPECTS OF EVAPORITE DEPOSITION

A review of evaporation rates implies that evaporite models requiring annual evaporation of over 500 cm of seawater may be rejected as imposslble. An examination of laminated sulfates shows that they cannot be annual because that would require annual evaporation many tlmes the physically possible rate. The recognition that Jehresringe, or laminated evapori tes, are non-annual leads to the rejection of Schmalz's (1966) formula that indicates that evaporites rwt be laid down in deep basins. Landes' (1960) Theory of Supersal ine Invading Seas must also fail, for it ultimately requires the,same unrealistic evaporation rates, even though it was formulated . to explain the abnormal proportions of mineral species in evaporite section. Two analyses of the King (1947) and Brlggs (1957) models for the deep-water orlgln of evaporltes show that they will not work; first, if they are placed in hydrostatic equilibrium, for then the water surface will not be horizontal. If the water in them is allowed to go to horizontallty , then the water will not be exposed to evapor- ation long enough to create evaporite-precip itating salinities. Secondly, an analysis of diffusion in these models shows that d iffusion is far more rapid than evaporative concentration, so that a deep water basin could neither de- velop evaporite-producing salinities nor could it maintain them even if it were filled originally with brine of suf- ficient salinity derived from some other source. in view of the inadequacies of all proposed models, I conclude that no deposition of evaporites is possible in deep water and that all evaporites must be products of shallow-water conditions.