Ichnology of a tropical delta and associated strandplain: the Oligocene–Miocene Ciénaga de Oro Formation of Colombia
Bibliographic record
Abstract
The Oligocene-Miocene Ciénaga de Oro Formation, located in the San Jacinto Fold Belt Basin (SJFB) of northwestern Colombia, records a complex interplay of fluvial, wave, and tidal (Fwt) processes. This study integrates sedimentologic and ichnologic data to reconstruct depositional environments and corresponding paleoecologic conditions. Two facies associations were identified: FA1 (deltaic), including distributary channels, interdistributary bays, lagoons, marshes, and delta front deposits; and FA2 (strandplain), comprising backshore, foreshore, and shoreface deposits. The succession reflects a deltaic system, varying laterally to a strandplain. Ichnologic analysis reveals archetypal ichnofacies, such as the Skolithos Ichnofacies in the high-energy shoreface, the Rosselia Ichnofacies in the delta front, and the Teichichnus Ichnofacies in the interdistributary bays and lagoons. These trace fossils indicate varying stress factors, including high sedimentation rates, alternating hydrodynamic energy conditions, elevated water turbidity, and salinity fluctuations, which influenced benthic communities. The stratal stacking pattern is progradational and aggradational, indicating that deposition occurred in a highstand systems tract (HST). This study provides a depositional model for mixed influence deltaic (Fwt) and strandplain systems in a tropical area, enhancing our understanding of the Oligocene-Miocene evolution of the SJFB and offering insights applicable to similar systems in low-latitude settings.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".