Abstract
This paper summaries 12 years of documentation of secondary halite deposits in the Iranian salt karst. A variety of secondary halite deposits was distinguished and classified into several groups, on the basis of the site and mechanism of their origin.
Deposits formed: i) via crystallization in/on streams and pools, ii) from dripping, splashing and aerosol water, iii) from evaporation of seepage and capillary water, and iv) other types of deposits. The following examples of halite forms were distinguished in each of the above mentioned group: i) euhedral crystals, floating rafts (raft cones), thin brine surface crusts and films; ii) straw stalactites, macrocrystalline skeletal and hyaline deposits, aerosol deposits; iii) microcrystalline forms (crusts, stalactites and stalagmites, helictites); iv) macrocrystalline helictites, halite bottom fibers and spiders, crystals in fluvial sediments, euhedral halite crystals in rock salt, combined or transient forms and biologically induced deposits.
The occurrence of particular forms depends strongly on the environment, especially on the type of brine occurrence (pool, drip, splashing brine, microscopic capillary brine, etc.), flow rate and its variation, atmospheric humidity, evaporation rate and, in some cases, on the air flow direction. Combined or transitional secondary deposits can be observed if the conditions changed during the deposition.
Euhedral halite crystals originate solely below the brine surface of supersaturated streams and lakes. Macrocrystalline skeletal deposits occur at places with rich irregular dripping and splashing (i. e., waterfalls, places with strong dripping from the cave ceilings, etc.).
Microcrystalline (fine grained) deposits are generated by evaporation of capillary brine at places where brine is not present in a macroscopically visible form.