The terms brines and evaporites are used in a generic way to describe concentrated solutions of ions and the chemical precipitates from those solutions. Based on the order of precipitation of evaporite minerals from brines of known composition, geochemists have deduced the chemistry of brines from which ancient evaporites have been deposited. Modern evaporite basins and their brines also serve as models to reconstruct the physical and temporal development of ancient evaporite deposits. The following discussion highlights some of the major geological aspects of hypersaline environments as well as chemical and physical aspects of brines. The discussion of brine chemistry emphasizes the factors that are important in biological productivity. The modern evaporite areas discussed in this book are shown in Figure 1.1.
