Conodonts, microfacies and palaeoenvironment during the mid-Tournaisian Event - comparison of platform and basin (lower Mississsippian, Germany and Belgium)
The globally traceable mid-Tournaisian Event (lower Carboniferous, Mississippian) was the result of glacio-eustatic sea-level fluctuations and its formation a matter of ongoing discussions. Two opposing sides postulate either a formation during a transgression or during an episode of a waxing ice sh...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | German English |
| Published: |
2021
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| Online Access: | https://kups.ub.uni-koeln.de/46175/ https://kups.ub.uni-koeln.de/46175/1/Diss_EstebanLopez_final.pdf |
| Summary: | The globally traceable mid-Tournaisian Event (lower Carboniferous, Mississippian) was the result of glacio-eustatic sea-level fluctuations and its formation a matter of ongoing discussions. Two opposing sides postulate either a formation during a transgression or during an episode of a waxing ice sheet. Here, an attempt is made to clarify the formation mechanisms, employing conodont biostratigraphy, conodont biofacies zonation, microfacies analysis and sequence stratigraphy. A review of the existing conodont biozonation models for the lower Carboniferous visualizes the differences that are the result of varying accumulation realms, and allows the correlation between the models. Sequence stratigraphy is used to support the correlation. The review also questions the usefulness of "standard" biozonation models as they cannot be applied to conodont faunas originating from shallow-water environments. Three studies from the Rhenish Mountains (Riescheid, Gladenbach, Wettmarsen) and one from the eastern Belgian Namur-Dinant Basin (Dolhain) represent different settings along a platform-basin transect and were used to reconstruct the conditions during the mid-Tournaisian Event. The section Riescheid, that is situated within the Herzkamp Syncline in the western Rhenish Mountains exposes middle Famennian to Upper Viséan strata of the Kulm facies (basin facies). The middle Tournaisian Kahlenberg Fm consists of dark shales and a package of intercalated calciturbidites and was accumulated during the Transgressive Systems Tract (TST) and Highstand Systems Tract (HST) of Sequence 2. The retrieved very poor conodont fauna indicates the affiliation to the isosticha-Upper crenulata Zone and the Siphonodellid Biofacies that represents lower slope to basin environments. The microfacies analysis allows the reconstruction of the sedimentational conditions. They reveal the accumulation of hemipelagic calciturbidites in distal, lower slope environments. The Gladenbach section, situated in the eastern Rhenish Mountains, exposes middle ... |
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