Corallian Limestone
Reef limestones (also Riffkalkstein ) are limestones, resulting from massive accumulations of corals, sponges and other sessile marine organisms. They occur mainly in coastal or other shallow marine regions. Unlike Schillkalken the calcareous skeletons have not been zusammengspült by sea waves but in the original habitat of the organisms, often preserved in life position ( in situ).
In today's oceans reef limestones are formed mainly by hard corals. The corresponding Riffkörper are therefore referred to as coral reefs. The usually tiny, but live in large colonies of coral polyps have the ability to deposit lime. They form meter - to hundreds of meters high reefs in the course of millennia. The reef limestones are partly also from Riffschutt, which was created by the ocean surf or earth movements. Often the structures that have generated the Riffbildner in the reef limestones still recognizable.
Properties and Uses
Reef limestones may be colored differently and have a banded or spot- like appearance. The colors of the reef limestones are usually whitish or yellowish, sometimes reddish, reddish brown, brown or gray to black.
The manifestations of reef limestones are very changeable because of the biological diversity in the former reefs. Typical characteristics are individual Riffbruchstücke and bioclasts as Stromatoporenteile, small pebbles of shellfish and coral pieces. They occur in dickbankiger, almost unstratified facies as well as in gebankter form.
The reef limestones are dense natural stone, therefore they are usually well polished. Often dense reef limestone are incorrectly referred to as marble, but they belong to the family of limestone rock. Polished reef limestones are used in architecture for interior wall cladding, flooring and stairs. Because of their decorative effect you have it temporarily very common to artistic and art used for commercial purposes.
Like other limestone reef limestones also be used as aggregates, such as in the ironmaking, or mined for cement production.
Massenkalk
Especially dickbankige and extensive Riffkalkvorkommen are often referred to with the term Massenkalk. Examples are known in Germany as from the Rhenish Slate Mountains. Here Middle Devonian reef limestones form in the Eifel, in the Bergische Land and Sauerland and in the Lahn- Dill area ( Lahnmarmor ) widespread limestone deposits, which are obtained in many places to limestone quarries and natural stone production. Typical index fossils of this Massenkalkes are the brachiopods ( Brachiopoda ) Stringocephalus Burtini and Uncites gryphus.
Other Massenkalke are known about from the Jura, in particular up to 500 m thick Jurassic in the Swabian and Franconian Alb. The calcification by sponges but ungebankt unlike coral reefs. Older, formed in the Triassic of the Alps reef limestone massifs are eg the Wettersteinkalk Tyrolean Wettersteingebirge.
Types of natural stone in Germany
Reef limestones were in Germany, since they can be polished, historically incorrectly referred to as marbles. Some examples are:
- Vineyard marble, consisting of Riffkalkschutt, Kerpen
- Cistercian marble, reef limestone, Üxheim Gerolstein / Eifel
- Precious rock marble, reef limestone, Diez an der Lahn