Rock-forming living being
Organisms that contribute to the formation of biogenic sedimentary rocks through their vital activity are referred to as rock-forming living beings or rock-forming organisms . The contribution here can consist in the provision of body substance (mostly parts of exoskeletons or endoskeletons, but also - for example in the case of brown or hard coal - organic material). Due to their way of life, the organisms can also serve as "traps" for non-biogenic sediment particles, whereby transitions are also possible: coral reefs, for example, act as sediment catchers on the one hand, and stony corals on the other hand produce inorganic skeletons that act asFossils also contribute to rock formation. Finally, the metabolic processes of the organisms outside their body can also induce the formation of inorganic particles, as in the case of the stromatolites formed from biofilms , which on the one hand act as sediment traps, on the other hand can cause the precipitation of calcium carbonate due to the assimilation of carbon dioxide . If the rock bodies formed by biological activity can be clearly distinguished from the surrounding sediments, one speaks of a bioherm .
Most organisms are calcareous skeletal material ready ( calcareous algae , foraminifera , cnidarians , sponges , bryozoans , molluscs , echinoderms , arthropods ), but also siliceous (may diatoms , radiolarians , silicoflagellates , siliceous sponge spicules) or phosphatisches (bones and teeth of vertebrates ) biogenic rock material Be of origin.
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- Dorrik AV Stow: Sedimentary rocks in the area. Spectrum, Heidelberg 2008, ISBN 978-3-8274-2015-2 .
- Ulrich Sebastian: Geology. 2nd edition, Spektrum, Heidelberg 2012, ISBN 978-3-8274-2822-6 .
- Hans Füchtbauer (Ed.): Sediments and sedimentary rocks. 4th edition, Schweizerbart, Stuttgart 1988, ISBN 3-510-65138-3 .