Halogenesis

Halogenesis is the process by which salt-rich deposits, known as evaporites, are formed from the evaporation of water. This typically occurs in arid or semi-arid climates where water bodies, such as lakes or seas, lose more water through evaporation than they gain through precipitation or inflow. As the water evaporates, the concentration of dissolved salts increases. Eventually, the solution becomes supersaturated, causing the salts to precipitate out of the water and accumulate on the basin floor.

Common minerals that form through halogenesis include halite (sodium chloride, common table salt), gypsum (calcium sulfate), and anhydrite (anhydrous calcium sulfate). These deposits can form in various geological settings, including inland lakes (playas), restricted marine basins, and even within the pore spaces of existing rocks. The accumulation of these evaporite minerals over geological time can lead to the formation of thick layers within sedimentary sequences.

The study of halogenesis is important for understanding ancient environments, as the types and structures of evaporite deposits can provide clues about the climate, water chemistry, and geological history of a region. Halite deposits, in particular, are of economic interest, serving as sources of salt for consumption and industrial use. They can also act as effective seals in geological formations, trapping hydrocarbons and other fluids.