Encrustatsioon

Encrustatsioon is a geological term referring to the process by which a mineral or material deposits on and covers a surface, often forming a layer or coating. This can occur in various natural environments, including marine, freshwater, and terrestrial settings. The encrusting material is typically precipitated from a solution, such as dissolved minerals in water, or it can be the accumulation of biological matter.

In marine environments, encrustation is commonly observed on hard substrates like rocks, shells, and ship hulls. Organisms such as corals, barnacles, bryozoans, and various algae can attach to surfaces and grow, forming thick layers. This biological encrustation can significantly alter the habitat and physical structure of the substrate. On a geological timescale, the accumulation of mineral deposits, like calcite or silica, can also lead to encrustation, forming stromatolites or cementing sedimentary grains together.

Freshwater environments also exhibit encrustation, though often with different organisms and mineral compositions. Calcareous deposits from dissolved calcium carbonate in hard water can lead to the formation of tufa or travertine, which are forms of encrustation. In some cases, microbial activity plays a crucial role in precipitating minerals and forming these structures.

Terrestrial encrustation can occur in caves, where mineral-rich water drips and evaporates, leaving behind speleothems like stalactites and stalagmites, which are essentially mineral encrustations. Desert varnish, a dark coating found on rocks in arid regions, is another example, often attributed to the action of clay minerals and iron or manganese oxides, possibly facilitated by microbial communities. The process of encrustation is driven by factors such as the availability of dissolved minerals, water flow, temperature, and biological activity.