Palaeoecological significance of calcimicrobial communities during ramp evolution: An example from the Lower Cambrian of Germany |
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Authors: | Dr Olaf Elicki |
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Institution: | (1) Geologisches Institut, TU Bergakademie Freiberg, D-09596 Freiberg |
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Abstract: | Summary The palaeoecology of calcimicrobial communities from the only Gondwana-related Lower Cambrian in Central Europe (eastern Germany,
carbonates and siliciclastics) has been studied. Six morphological groups of calcimicrobes are described. Some of them show
a significant ability for sediment stabilization and construction of biohermal reef mounds. Other types of calcimicrobes were
more common in biostromal thickets. Some of them were capable of populating different environments, growing in different modes
and on different substrates. AnEpiphyton-archaeocyathan reef mound is described, illustrating the importance of calcimicrobes for mound formation. The fossil communities
together with a complex of sedimentary features allow a reconstruction of the depositional history of the environment. Based
on comparison with similar Gondwanan Lower Cambrian successions (Sardinia/Italy, Spain) and facies development a model is
proposed describing the sedimentary history. Three depositional stages are distinguished: (1) deep subtidal ramp, (2) shallow
subtidal ramp, (3) shallow subtidal to intertidal mixed siliciclastic-carbonate ramp with migrating oolitic shoals. In spite
of similarities with the deposits in southern Europe, some distinct differences exist with respect to the succession of facies,
the completeness of the sections, the fossil spectrum, and the nature of the siliciclastic sediments. For the German Lower
Cambrian, a facies development from a low energy deep environment to a high energy shallow environment (partly restricted
and with some evaporites) can be reconstructed. As compared with Sardinia and Spain, the depositional environment of the eastern
German Lower Cambrian successions was predominantly characterized by low-energy conditions. |
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Keywords: | Calcimicrobes Palaeoecology Carbonateramps Reefs Germany Lower Cambrian |
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