There are many lakes in the world. These lakes can be divided into freshwater lakes and saltwater lakes according to the salt content of the lake water. Among them, the lake with a salt content of more than 35% is called a salt lake. For example, the Chaka Salt Lake in Chaka Town, Qinghai Province, due to the reflection of the brine on the crystalline salt layer of the lake surface, forming a mirror effect.
Where did the salt material that formed the salt lake come from?
There are four main sources:
- From surface rock or salt deposits near the salt lake. These salty ores are eroded by wind and water, and the dissolved substances enter the lake to form a salt lake.
- Magma and escaping gaseous materials from volcanic eruptions. Volcanic magma contains potassium, sodium, calcium, magnesium and other soluble silicates, which dissolve in lake water to form a salt lake.
- Overflow of deep brine. Deep brine flows into the lake continuously through deep crustal faults, forming a salt lake.
- Transmission from wind. Salt, which is easily soluble in water, is blown into the lake by strong wind to increase salt for the lake.
The formation of salt lakes needs to meet three conditions.
First, there must be a closed or semi-closed catchment lake basin. Such a closed terrain is conducive to the continuous flow of water resources and energy sources such as runoff and rainwater in the watershed into the lake basin without leakage, forming an aggregated state.
Second, the lake must have continuous dry climate conditions. Under such climatic conditions, the amount of evaporated water in the lake exceeds the amount of added water. Moreover, under intense evaporation, the lake water is continuously concentrated, and the salt content gradually increases, forming different types of salt deposits at the bottom of the lake to form a salt lake.
Third, the sources of salt in different salt lakes are diverse, but they all require abundant salt materials to continuously enter the lake to ensure that the salt lake has a certain salinity.
There are many lagoons in the world, and their types are also different. Generally speaking, there are three principles for dividing the types of salt lakes: According to the salt lake brine occurrence status, it can be divided into brine lake, dry salt lake and Shaxia lake. According to the classification of salt minerals formed by the main salt deposits of salt lakes, they can be divided into stone salt lakes, thenardite lakes, and trona lakes, as well as gypsum lakes, potassium-magnesium salt lakes, lithium lakes, and world rare nitrate (potassium) salt lakes. In addition, according to the classification of salt lake brine chemical composition, salt lake can be divided into carbonate type, sulfate type and chloride type.
In areas where salt lakes are distributed, “white necklaces” around the lake are often seen-a circle of silver-white salt belts. These “necklaces” are formed when salt materials migrate from the basin to the salt lake. During the migration of various salts dissolved in water from the watershed to the salt lake, the water continues to evaporate in the dry and hot environment. Over time, the more salt accumulates in the lake, the precipitation will occur when it reaches saturation or supersaturation. Due to the different solubility of various salts, there is a certain precipitation sequence, which makes the sediment of various salts present a distinct ring-shaped distribution, like wearing a “necklace” for the salt lake.