Quantifying the invisible: pXRF analyses of three boreholes, British Columbia and Ontario
Bibliographic record
Abstract
Portable X-ray fluorescence (pXRF) technology collects geochemical data at a fraction of the cost of traditional laboratory methods. Although the pXRF spectrometer provides concentrations for 41 elements, only a subset of these elements meet the criteria for definitive, quantitative, and qualitative data. However, high-quality pXRF data obtained by correct application of analytical protocols, can provide robust insight to stratigraphy and sediment characteristics that are often not observed by, for example, visual core logging, grain size analysis, and geophysical logging. We present examples of geochemical results obtained from pXRF analysis of drill core samples from three boreholes located in Canada, that demonstrate: 1) Definitive stratigraphic boundaries observed in geochemical changes obtained from 380 analyses collected over 150 m of core, which intersects three Ordovician sedimentary formations and Precambrian granite. These boundaries could not be reconciled by traditional visual core logging methods. 2) Significant elemental concentration changes observed in 120 samples collected in each of two ~120 m deep boreholes located in a confined paleo-glacial foreland basin. The collected geochemical data provide insight to sediment provenance and stratigraphic relationships that were previously unknown. 3) Abrupt changes in the geochemical signature in a subset of 135 samples collected from a 151 m deep borehole intersecting Quaternary glacial derived till, sands, and ahomogeneous silt and clay succession. These data provide a platform for discussion on ice sheet dynamics, changes in depositional setting, and changes in provenance. Results from each of these studies highlights previously unknown (invisible) geological information revealed through geochemical analyses. A significant benefit of using pXRF technology is refining sampling strategies in near real time and the ability to increase sample density at geochemical boundaries with little increase in analysis time or budget. The data also provide an opportunity to establish a chemostratigraphic framework that complements other stratigraphic correlation techniques, including geophysical methods. Overall, data collected with pXRF technology provide new insights into topics such as spatial correlations, facies changes, provenance changes, and depositional environment changes.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".