Vorkommen fossiler Charophyten in Deutschland

Zusammenfassung

For geological research in Germany, fossil charophytes generally play a rather exotic, but sometimes significant role. This is especially true for the biostratigraphy (dating and correlation of rock successions) within non-marine sediments holding carbonates and marls (for Germany: mainly upper Jurassic to basal Cretaceous and Oligocene to Miocene). More generally, charophytes are often used for a simple first estimation of the depositional environments of sedimentary rocks. Here, charophyte remains (usually quite easily recognizable) simply serve as indicators for non-marine environments (fresh or brackish waters). For most geologists and carbonate specialists, the latter is certainly by far the most important benefit of the fossil remains of this group of algae.

The fossil record of charophytes in Germany starts with the Devonian (middle Paleozoic): In rocks from this time, charophytes are quite common in (at least in certain horizons). One of its most important genera (Sycidium) was first described here, and also a few other genera from Germany have been important for the research on Devonian charophytes in general. Furthermore, the paleoecological consequences of frequent associations of Sycidiales and Trochiliscales with marine faunas are still under controverisal discussion.

On the contrary, the few findings of charophytes in Carboniferous, Permian and Triassic and Middle Jurassic rocks of Germany are rather insignificant and – in an international context – of minor importance.

In contrast, parts of the German upper Jurassic and basal Cretaceous are extremely rich in charophytes. A number of fossil genera was first described here (Porochara, Latochara), as well as numerous species of other genera. In general, the study of the charophytes from this period provided an important input to the systematics, phylogeny, and paleoecology of fossil charophytes – as well as to the development of supraregional biostratigraphic zonations.

During the following period of time (middle to to upper part of the Lower Cretaceous, the entire Upper Cretaceous and the first section of “Tertiary” (Paleocene/most of the Eocene), charophytes were very rare and played a minor role again.

This changes again very significantly for the Oligocene and Miocene series. Some of the charophyte deposits in Germany played an important role for the development of the European charophyte biozonation for the Paleogene and Neogene, mainly deposits in the Oligocene of the Mainz Basin (European Rhabdochara major, Chara microcera and C. notata zones).