Chemotrophy-based phosphatic microstromatolites from the Mississippian at Drewer, Rhenish Massif, Germany

Zwicker J, Smrzka D, Gothieu M, Libowitzky E, Joachimski M, Ernst Böttcher M, Peckmann J (2023)

Publication Type: Journal article

Publication year: 2023

Journal

Geological Magazine Cambridge University Press (CUP)

DOI: 10.1017/S0016756823000493

Abstract

The Drewer quarry located in the Rhenish Massif is a well-studied outcrop that comprises Upper Devonian (Famennian) to Lower Carboniferous (Viséan) strata. Within the Drewer deposits two black shale intervals have been described that are linked to two global oceanic anoxic events, the Hangenberg Event and the Lower Alum Shale Event. The black shales associated with the Middle Tournaisian Lower Alum Shale Event contain abundant phosphatic concretions, which were investigated using thin section petrography, powder X-ray diffraction, Fourier-transform infrared spectrometry and scanning electron microscopy. The concretions formed during several growth phases under anoxic and at least episodically sulphidic conditions within the sediment and served as a substrate for subsurface microbial mats that formed phosphatic microstromatolites. The microstromatolites occur either as partially branched columns of up to 600 μm in length attached to the phosphatic concretions or as smaller, bulbous aggregates surrounding the concretions. Element mapping identified the presence of pyrite and other metal sulphides within the phosphatic microstromatolites. The carbon and oxygen stable isotopic composition of phosphate-associated carbonate within the phosphatic microstromatolites suggests that the mat-forming microorganisms were probably anaerobic, chemotrophic microbial communities dwelling in the anoxic environment during the Lower Alum Shale Event. Such interpretation agrees with the deeper-water depositional setting of the Lower Alum Black Shale and its high content of organic matter, suggesting that chemotrophic microbial mats are potent agents of phosphogenesis in general, and of the formation of phosphatic stromatolites in particular.

Authors with CRIS profile

Michael Joachimski Lehrstuhl für Geologie (Exogene Dynamik)

Involved external institutions

Universität Hamburg (UHH) DE Germany (DE) Leibniz-Institut für Ostseeforschung / Leibniz Institute for Baltic Sea Research DE Germany (DE) Universität Wien / University of Vienna AT Austria (AT) Universität Bremen DE Germany (DE)

How to cite

APA:

Zwicker, J., Smrzka, D., Gothieu, M., Libowitzky, E., Joachimski, M., Ernst Böttcher, M., & Peckmann, J. (2023). Chemotrophy-based phosphatic microstromatolites from the Mississippian at Drewer, Rhenish Massif, Germany. Geological Magazine. https://doi.org/10.1017/S0016756823000493

MLA:

Zwicker, Jennifer, et al. "Chemotrophy-based phosphatic microstromatolites from the Mississippian at Drewer, Rhenish Massif, Germany." Geological Magazine (2023).

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