Coral Oolite

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In the lithostratigraphy of north-west Germany, a rock formation from the upper Jura ( Malm ) is referred to as coral oolite , which was deposited around 155 to 152 million years ago. According to the stratigraphic tables 2002 and 2012, the coral oolite is classified in the upper Oxford .

The coral oolite comprises several layers of sedimentary rocks, including the characteristic calcoolites and oolithic iron ore. The sedimentation took place in a shallow sea, in which sufficient light was possible for corals to grow due to the shallow water. A warm climate and slight wave movements made it possible for calcite to precipitate in the Upper Jurassic, with the seawater being correspondingly oversaturated. Small particles (e.g. quartz grains or shell fragments) serve as a mineralization nucleus, whereby calcite attaches to the particles. The wave movement created concentric layers of calcite around the crystal nuclei. These small spherical mineral grains are called ooidsdesignated; they grow to a maximum of 2 mm. The deposition environment for ooids is a sea area near the beach, shallows or flow channels. A rock consisting mainly of ooids is called an oolite .

The Korallenoolith is bounded below by the Heersumer strata , above by the Süntel formation . It is roughly subdivided into the Lower Korallenoolith and the Upper Korallenoolith. The period of deposition of the Lower Korallenooliths as well as the Heersum strata falls within the Oxford of the international hierarchy. In terms of time (chronostratigraphically), the upper coral oolith is already in Kimmeridge .

The Hohenstein in the Süntel consists of the gray limestone of the Korallenoolith. In numerous quarries in northwest Germany (e.g. on Langenberg in the northern Harz foreland), building lime and aggregates for road construction are extracted from the limestone layers of the corallenoolite . Oolithic iron ore is mined in the Weser Mountains, for example , where it is up to 25 meters thick.

Individual evidence

1. ^ STD 2002 (German Stratigraphic Commission): Stratigraphic Table of Germany 2002 . Ed .: M. Menning & A. Hendrich. GeoForschungsZentrum, Research Inst. Senckenberg, Potsdam, Frankfurt a. M. 2002, ISBN 3-00-010197-7 .
2. ↑ ^{a b} STDK 2012 (German Stratigraphic Commission): Stratigraphic Table of Germany . Ed .: M. Menning & A. Hendrich. German Research Center for Geosciences, Potsdam 2012.