Precipitation of Sulfates and Chlorides by Mixing Seawater Brines: ABSTRACT

Experiments using artificial and seawater brines indicate that gypsum, halite, and sylvite can be precipitated by mixing brines at differing stages of evaporation, as well as by the previously recognized mechanisms of direct evaporative crystallization and crystallization by temperature changes. A modification of existing geologic models is proposed to show how brine mixing might work in an evaporite basin. Conclusions based on the experiments and their relations to the geologic model are as follows: 1. Precipitation of salts can occur in a marine evaporite basin by mixing brines of different composition and specific gravity. 2. Precipitation occurs without further water loss by evaporation. 3. Precipitation can occur from brines that were undersaturated before mixing. 4. Brine mixing could cause different salts to be deposited in different parts of a basin depending on the stage of the evaporite cycle. 5. Sylvite could be precipitated as a primary mineral. 6. Hopper crystals (cubic and tabular) of sodium chloride can form as a result of brine mixing in water of any depth. End_of_Article - Last_Page 647------------