Geochemistry and cyclostratigraphy of homogeneous deposits using high-resolution hand-held X-ray Fluorescence: Outcrop to subsurface correlation, sequence stratigraphy, and constraints on hiatuses (middle-Upper Eocene, Tunisia)
Bibliographic record
Abstract
Abstract This paper aims to determine the applicability of the handheld X-ray fluorescence (HH-XRF) for studying homogenous deposits, which finds essential applications in economic geology and paleoenvironmental studies. We tested using the HH-XRF in thick mudstone series to delineate the sequence stratigraphic framework and redox conditions in the deep-water section and for outcrop to well correlation in the shallow water deposits. Samples that exhibit maximum or minimum values for Si and Ti elements were chosen for the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis to help establish sequence boundaries. A comparison of HH-XRF and ICP-MS for measuring major and minor element concentrations was applied to validate the HH-XRF data. The data was normalized by Al and Ti to reveal the major trends. Si/Al and Si/Ti measurements have proven particularly useful for delignating sequences in homogeneous deep-water mudstones and cyclostratigraphy. Changes in Mo/Al, As/Al, V/Cr, V/(V + Ni) and isolated peaks in Sulphur during the Lutetian – Bartonian transition have been related to Maximum Flooding Surfaces (MFS) or Sequence Boundaries (SB). They are, therefore, associated with condensation or no deposition rather than a significant change in oxygenation conditions in the bottom waters of the outer ramp of our basin. Consequently, they do not truly reflect dysoxia but rather the peculiar chemical conditions associated with condensation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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 source (direct Gemma or distilled Codex), 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".