Inorganic geochemical characterisation of the cretaceous marine and continental sediments in the Keana area of the middle-Benue trough, north-central Nigeria: Its implication in tectonic setting, provenance and depositional environment
Bibliographic record
Abstract
Sandstone, shale and limestone, constitute the lithological units occurring in the southern part of the Middle-Benue Trough of Nigeria. The geochemistry of major, trace and rare earth element (Na2O, K2O and Ba, Cu, Zn, Co, Sc, Ni, Cr, V, Th, U, Nb, Rb, Sr, Zr, and Y) of the Cretaceous marine and continental sediments belonging to the Asu-River Group, Awe, Keana, Ezeaku and Agwu formations was carried out to determine the provenance, tectonic setting and depositional environment of the sediments. AIMS AND OBJECTIVES. * To determine the lithostratigraphy of the area through field geological mapping. * To carry out petrographic analysis. * To carry out major, trace and rare earth element geochemical analysis of the sediments. * To classify the rocks, deduce their tectonic setting and source rock potential based on field, petrographic and geochemical criteria. PROCEDURES Thirteen shale and limestone samples and three samples of nodules from my study area were pulverized in the Department of Geology and Mining. They were analysed for major, trace and rare earth elements at the ACME laboratories limited (code: VAN1204168), Vancouver Canada. The analytical technique employed is the ultra-trace analytical package which uses the ICP mass spectrometry method of geochemical samples; samples were subjected to high temperature dissociate into atoms which in the process cause significant amount of collision excitation and ionization of sample atom. Results of the analysis were used in interpreting to deduce their Tectonic Setting, Provenance and Depositional Environment. RESULTS Chemical analysis show that the sediments are depleted in Na2O which may be due to intense chemical weathering at source rock area during fluvial transportation of detrital materials. Al2O3/TiO3 ratio (8-21%), La/Sc, Th/Sc, La/Co ratios, Cr, Th values points to an intermediate- felsic provenance under different tectonic environments. Na2O/K2O ratio of less than 1 indicates matured sediments while the Ni/Co ratio (<5), V/V+Ni ratio (<9) and low value Cu/Zn ratio indicates an oxic environment of deposition and the Th/U ratio (<7) strongly suggest a dominantly marine environment. CONCLUSION The oxic marine environment provided a conducive environment for organisms that could have destroyed the hydrocarbon producing materials to thrive, thus making the environment unfavourable for the production of hydrocarbon especially the light crude.
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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".