Displacive Halite Hoppers from the Dead Sea: Some Implications for Ancient Evaporite Deposits

ABSTRACT Large hopper-shaped halite cubes (up to 10 cm on a side) grow displacively within Holocene sediments near the southern end of the Dead Sea, under conditions of high temperatures, ionic concentrations and rapid rates of crystallization. Two theories of formation are presented: downward diffusion of ions versus upward diffusion, and "evaporative pumping." Both alternatives are considered possible, and the correct choice probably depends upon the location of the sediments at the time of precipitation--whether subaqueous or subaerial--a choice indeterminate at present, because of human disturbance to the sediments prior to collection. Displacively formed halite crystals, similar in morphology to the Dead Sea cubes, are common in evaporite-bearing carbonate rocks of many regions, such as the Salina Fm. (U. Silurian), Michigan Basin; the Kirkham Mudstone (U. Triassic), Cumbria, England; and the U. Miocene Gessoso-Solfifera Fm. of Sicily. These are believed to have formed under conditions analogous to those in the present Dead Sea. These observations taken together with those of other authors may now be used for the facies interpretation of ancient halite deposits.