scholarly journals Asymmetry of an epicontinental basin-facies, cycles, tectonics and hydrodynamics: The Triassic Upper Muschelkalk, South Germanic Basin

2019 ◽  
Vol 5 (1) ◽  
pp. 147-187 ◽  
Author(s):  
Matthias Warnecke ◽  
Thomas Aigner
Keyword(s):  
Germanic Basin ◽  
Upper Muschelkalk

scholarly journals Late Anisian microbe-metazoan build-ups ('stromatolites') in the Germanic Basin — aftermath of the Permian — Triassic Crisis

2021 ◽  
Author(s):  
Yu Pei ◽  
Jan-peter Duda ◽  
Jan Schoenig ◽  
Cui Luo ◽  
Joachim Reitner
Keyword(s):  
Microbial Mats ◽  
Middle Triassic ◽  
Ecological Niches ◽  
Carbon And Oxygen Isotopes ◽  
Germanic Basin ◽  
Sulfate Reducing ◽  
Mutualistic Relationship ◽  
Relative Rarity ◽  
Geochemical Analyses ◽  
Reducing Bacteria

The so-called Permian — Triassic mass extinction was followed by a prolonged period of ecological recovery that lasted until the Middle Triassic. Triassic stromatolites from the Germanic Basin seem to be an important part of the puzzle, but have barely been investigated so far. Here we analyzed late Anisian (upper Middle Muschelkalk) stromatolites from across the Germanic Basin by combining petrographic approaches (optical microscopy, micro X-ray fluorescence, Raman imaging) and geochemical analyses (sedimentary hydrocarbons, stable carbon and oxygen isotopes). Paleontological and sedimentological evidence, such as Placunopsis bivalves, intraclasts and disrupted laminated fabrics, indicate that the stromatolites formed in subtidal, shallow marine settings. This interpretation is consistent with δ13Ccarb of about -2.1 % to -0.4 %. Occurrences of calcite pseudomorphs after gypsum suggest slightly evaporitic environments, which is well in line with the relative rarity of fossils in the host strata. Remarkably, the stromatolites are composed of microbes (perhaps cyanobacteria and sulfate reducing bacteria) and metazoans such as non-spicular demosponges, Placunopsis bivalves, and/or Spirobis-like worm tubes. Therefore, these ″stromatolites″ should more correctly be referred to as microbe-metazoan build-ups. They are characterized by diverse lamination types, including planar, wavy, domal and conical ones. Microbial mats likely played an important role in forming the planar and wavy laminations. Domal and conical laminations commonly show clotted to peloidal features and mesh-like fabrics, attributed to fossilized non-spicular demosponges. Our observations not only point up that non-spicular demosponges are easily overlooked and might be mistakenly interpreted as stromatolites, but also demonstrate that microbe-metazoan build-ups were widespread in the Germanic Basin during Early to Middle Triassic times. In the light of our findings, it appears plausible that the involved organisms benefited from elevated salinities. Another (not necessarily contradictory) possibility is that the mutualistic relationship between microbes and non-spicular demosponges enabled these organisms to fill ecological niches cleared by the Permian — Triassic Crisis. If that is to be the case, it means that such microbe-metazoan associations maintained their advantage until the Middle Triassic.

The Bioclastic Limestones of the “Trochitenkalk” (Upper Muschelkalk) in SW Germany

1968 ◽  
pp. 205-214 ◽  
Author(s):  
Manfred P. Gwinner ◽  
Gerhard Bachmann ◽  
Karlheinz Schäfer ◽  
Klaus Skupin
Keyword(s):  
Upper Muschelkalk

Trace fossils from the Lower Muschelkalk of Raciborowice Górne (North Sudetic Synclinorium, SW Poland) and their palaeoenvironmental interpretation

2013 ◽  
Vol 63 (3) ◽  
pp. 315-353n ◽  
Author(s):  
Alina Chrząstek
Keyword(s):  
Trace Fossils ◽  
Carbonate Ramp ◽  
Trace Fossil ◽  
Germanic Basin ◽  
Sw Poland ◽  
Bathymetric Changes ◽  
Lower Muschelkalk ◽  
Short Episode

Abstract The following trace fossils have been recognised in the Lower Muschelkalk of Raciborowice Gorne (North Sudetic Synclinorium, SW Poland): Archaeonassa fossulata, Balanoglossites triadicus, ?Gastrochaenolites isp., Lockeia isp., Palaeophycus tubularis, Palaeophycus isp., ?Planolites beverleyensis, P. montanus, Planolites isp., ?Protovirgularia isp., Rhizocorallium commune var. auriforme, R. commune var. irregulare, R. jenense, Skolithos linearis, Thalassinoides suevicus and Trypanites weisei. Coprolites and an unidentified trace fossil A are also described. The trace fossils allow the discrimination of five ichnoassociations in the Raciborowice Gorne section: (IA 1) Rhizocorallium- Pholeus, (IA 2) Rhizocorallium-Palaeophycus, (IA 3) Thalassinoides, (IA 4) Trypanites-Balanoglossites and (IA 5) Planolites-Palaeophycus. The Lower Muschelkalk succession was deposited on a shallow carbonate ramp affected by frequent storms. Deposition commenced with sedimentation in a restricted lagoon on the inner ramp with a short episode of sabkha formation. It continued on the middle and outer ramp and then on a skeletal shoal of the outer ramp and in an open basin. Ichnoassociation IA 5 is related to a maximum transgression that commenced with the deposition of the Spiriferina Bed and which probably marked the opening of the Silesian-Moravian Gate. The basin underwent two shallowing episodes, as evidenced by ichnoassociations IA 3-IA 4, resulting in the formation of hardgrounds. Bathymetric changes in the Raciborowice Gorne section correspond well with a general transgressive trend in the Germanic Basin.

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