Exploring the significance of true substrates in a Pennsylvanian fluvio-estuarine tidal flat
Date
2025-01-25
Authors
Buatois, Luis
Mángano, M. Gabriela
Maples, Christopher G.
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Geological Society Special Publications
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Article
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Abstract
The Pennsylvanian Tonganoxie Sandstone of Kansas contains examples of true substrates in tidal rhythmites formed in a tidal flat at the fluvio-estuarine transition of a macrotidal valley. These surfaces are characterized by an impressive preservation of biogenic and physical sedimentary structures, indicative of the coexistence of low-energy tidal currents and freshwater conditions together with brief periods of subaerial exposure. Biogenic activity corresponds to a time of stasis during or immediately after accumulation of ebb-phase clay
followed by low tide. Deposition-stasis-deposition (D-S-D) was involved in the formation and preservation of these true substrates, with only a few instances of deposition-stasis-erosiondeposition (D-S-E-D). Crosscutting relationships among biogenic structures and of these with physical sedimentary structures suggest a tidally controlled taphonomic pathway, which indicates that these true substrates represent short-term time-averaged surfaces at the scale of a few hours, rather than snapshots. True substrates preserved in tidal rhythmites are widespread in other late Palaeozoic tide-dominated estuarine deposits of the North American Midcontinent. The likelihood and quality of preservation seem to show spatial and temporal trends at various scales that ultimately reflect a complex interplay of abiotic factors (e.g. sedimentary dynamics) and biotic factors (e.g. secular changes in intensity and depth of bioturbation).
Description
The published version is found in the Lyell Collection found at: https://doi.org/10.1144/SP556-2024-118
Buatois, Luis A, M. Gabriela Mángano, and Christopher G Maples. (2025). “Exploring the Significance of True Substrates in a Pennsylvanian Fluvio-Estuarine Tidal Flat.” In Bedding Surfaces: True Substrates and Earth’s Historical Archive. The Geological Society of London, 556. https://doi.org/10.1144/SP556-2024-118
Keywords
substrates, fluvio-estuarine, deposition-stasis-erosiondeposition
Citation
Buatois, Luis A, M. Gabriela Mángano, and Christopher G Maples. (2025). “Exploring the Significance of True Substrates in a Pennsylvanian Fluvio-Estuarine Tidal Flat.” In Bedding Surfaces: True Substrates and Earth’s Historical Archive. The Geological Society of London, 556. https://doi.org/10.1144/SP556-2024-118
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DOI
https://doi.org/10.1144/SP556-2024-118