Cretaceous and Cenozoic calcareous nannofossil biostratigraphy of the NW inland basins of Colombia
Bibliographic record
Abstract
Calcareous nannofossils, a well-calibrated group of marine microfossils, are widely used to date and correlate Mesozoic and Cenozoic deposits. Despite their importance, relatively few studies have focused on these fossils in onshore deposits of South America. To address this gap, we analyzed calcareous nannofossils from several basins in the Caribbean, Pacific, and inter-Andean regions of Colombia, aiming to develop a regional framework for dating and correlating marine deposits. Our findings indicate that diagenesis significantly affects preservation of microfossils, and that nannofossil abundance is notably lower in coastal and deltaic deposits. Even so, we identified fourteen well-preserved assemblages that serve as key biostratigraphic markers, indicating ages from the Aptian (Cretaceous) to the Calabrian-Chibanian (Quaternary). By integrating these results with existing biostratigraphic data from foraminifera, palynomorphs, diatoms, and ammonites, we constructed a chronostratigraphic framework that compiles and summarizes biostratigraphic, sedimentary, and lithostratigraphic information. This regional perspective on the tropical basins of Colombia is critical for understanding the geological evolution of the Caribbean Sea and the eastern Pacific Ocean. • 10+ years of calcareous nannofossil research across Colombian Caribbean, Pacific, and inter-Andean basins. • Fourteen nannofossil assemblages indicate ages from Aptian (Cretaceous) to Calabrian–Chibanian (Quaternary). • Integrated nannofossil data with foraminifera, palynology, diatoms, and ammonites for chronostratigraphy. • This chronostratigraphic framework compiles biostratigraphy, sedimentology, lithostratigraphy for NW South American basins.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.005 |
| 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".