Euxinian
As euxinisch refers to a natural environment, the anoxic , that is free of oxygen or in oxygen, and hydrogen sulfide (H 2 S). Such milieus occur mainly in waters and their sediments . The hydrogen sulfide can get into the water through volcanic outgassing from the earth's interior, but more often it is produced in the water through bacterial reduction of sulfate (SO 4 2− ) ( desulfurication , sulfate-reducing bacteria).
In geology , sediments that were deposited in a euxinic, i.e. oxygen-poor or oxygen-free (anoxic), hydrogen sulfide-containing environment are referred to as euxinic . These sediments are black due to the precipitation of iron sulfides (FeS to FeS 2 ) and the carbonization of organic substances. Such sediments can be consolidated into sedimentary rocks through diagenesis and are then referred to as black slate , among other things .
The word Euxinian comes from the Latin name of the Black Sea , Pontus Euxinus . There a euxinic sediment, a digested sludge ( sapropel ), is deposited in the depths .