Quantifying a tide-dominated, wave-, and river-influenced delta in Miocene facies of the Niger Delta basin
Bibliographic record
Abstract
ABSTRACT The modern Niger Delta has long been classified as a mixed tide-, wave-, and river-influenced delta. Still, no detailed studies have quantified the relative proportions of formative processes and facies. This work presents the first quantitative estimate of the relative influence of formative processes in Miocene deposits based on core data from the Greater Ughelli, Central Swamp, and Coastal Swamp depositional belts of the Niger Delta basin. Facies analysis of 288.2 m of core from four wells shows approximately 53% tidal facies, 33% fluvial facies, and 14% wave-formed facies, indicating deposition in a prograding tide-dominated, wave-, and river-influenced delta. Cores from the Greater Ughelli and Central Swamp depobelts exhibit coarsening-upwards, prograding deltaic facies successions overlain by fluvial mudstone. Tidal deposits in the Coastal Swamp depobelt show coarsening-upwards prograding deltaic facies successions with well-developed tidal bundles indicating seasonal deposition. The basal part of these facies successions also reveals repeated floods characterized by slump and load structures and dewatering features. Delta-plain and delta-front–prodeltaic facies associations are identified based on physical sedimentary and biological structures. The delta-plain facies association consists of weakly bioturbated mudstone, fissile mudstone, and coarse-pebbly stratified sandstone facies with sparse trace fossils. The delta-front–prodeltaic facies association contains muddy and sandy heteroliths, stratified, medium and coarse-grained, cross-bedded sandstone, and convoluted mudstone facies. The facies vary but characteristically contain trace-fossil assemblages of the recently proposed Rosselia and Phycosiphon Ichnofacies, indicating delta-front and prodeltaic settings, respectively. Variability in the facies is determined by the relative influence of hydrodynamic processes (tide, wave, and river), variations in physicochemical stress, and the episodic character of deposition. In addition, based on the relative influence of each hydrodynamic processes, the facies differ through the successions, sometimes subtly.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".