Stratified limestone
Schichtkalk (stone) , also Bankkalk (stone) mentioned are sedimentary rock body , characterized by limestone , marl limestones, distinguished Kalkmergelsteine, etc., in the digestion show a clearly visible stratification, the layers being platy or usually bankig secrete. It is not a sedimentological term or a special facies term . The name only serves to distinguish it from unlayered (massive) limestone bodies, whereby the latter must be differentiated into mass limestone (i.e. reef limestone) and unlayered fine-grain limestone (e.g. the Rügen chalk ).
Individual layers or layer packages of such sequences can be characterized by a particularly high hardness and are therefore mined as natural stone . The corresponding layers are also called work stone benches in German .
Layered limestones are usually of marine origin. They arise when relatively fine limestone particles sink to the sea floor. The stratification is created by the fact that the environmental conditions change slightly during the deposition, so that sometimes more and sometimes less calcium carbonate is produced in the water column and is deposited. During diagenesis , calcium carbonate can be dissolved from layers with a slightly lower calcium content and precipitated again in layers with a higher calcium content, whereby the original change of material can be accentuated even more or only become visible to the naked eye. Periodically larger amounts of coarse limestone particles, often in the form of fossil debris as a result of z. B. storm events or landslides in the deposit area and then form appropriate ( tempestitic or turbiditic ) intermediate layers.
Layered limestones occur all over the world in carbonate series of virtually every geological age . In Germany they are particularly typical for the Muschelkalk ( Middle Triassic ) and the Malm / Weißjura ( Upper Jura ). Appropriate reserves are found anywhere outside the plot Mountain risers in the Low Mountain Range and in the Süddeutsche cuesta landscape .