The stratigraphy of ponded submarine fans in sections around Arta region and the presence of trace fossils in them as the means to identify the evolution conditions of the basin
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Date
2025-02-19
Authors
Ζεληλίδης, Παναγιώτης
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Abstract
The studied deposits are located around Arta region, organized into 13 sections in two sub-regions, one on the Northeast and one on the Southeast. They correspond to the upper part of submarine fans that accumulated in the Pindos foreland basin and consist mostly of thin- to medium-bedded sandstones and mudstones, whereas conglomerates are absent, indicating probably a lower level of environmental energy, despite the proximity to the Gavrovo thrust, or to the uplifted basement of Pindos Zone. The presence of sedimentary structures that are common in submarine fan systems agree with previous results that propose development of such systems in a foreland basin. The absence of massive to normal graded sandstones (Ta) could be related mostly with the long distance from the source or with the lower basin floor inclination gradient and thus the lower energy conditions. Statistical analysis of the different sedimentary facies showed the high contribution of the Tc sub-division and the Ta absence indicating the low energy conditions. Additionally, the presence of some successive sandstone beds with erosional contacts and the presence of amalgamation surface indicates repetitive flows. Finally, the repetitions of thin-bedded mudstones and sandstones (deposited in a ponded basin) probably could be related with either interchannel deposits or with crevasse splay deposits. In the absence of exposed channel deposits, it is supposed that the studied area represents the interchannel deposits. The statistical analysis of the interbedded sandstone and mudstone bed thicknesses showed a weak relation with a sandstone to mudstone ratio <1 and this fact could be related to the restriction of the basin due to which the mudstone suspension was trapped within the basin. Age determination, based on foraminifera points to a late Eocene up to early Oligocene age, in contrast to the early and late Oligocene age based on nannoplankton from previous studies. Considering the proximity to the Pindos thrust, the major sedimentary source of Pindos foreland, the late Eocene to early Oligocene age is supported for the upper part of Pindos foreland basin. Finally, as determined by the use of trace fossils the depositional environment seems to be a deep-sea with high oxygen conditions which matches well the ponded basin theory we consider as the most probable depositional palaeoenvironment.
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Keywords
Trace fossis, Ponded basin, Submarine fans, Stratigraphy, Statistical analysis