Pressure-Temperature-Fluid Constraints for the Formation of the Halo-Shakiso Emerald Deposit, Southern Ethiopia: Fluid Inclusion and Stable Isotope Studies
Bibliographic record
Abstract
ABSTRACT The Halo-Shakiso emeralds were discovered near the town of Shakiso in southern Ethiopia in 2016. They are gem quality, Cr-dominant emeralds hosted within ultramafic rocks and associated with Cambrian pegmatite intrusions of the Adola Belt. Aqueous-carbonic primary fluid inclusions hosted within emerald have a composition of approximately 3.0 wt.% NaCl eq. and an XCO2 of 0.06, with minor amounts of N2, CH4, and H2S. Stable isotope thermometry of contemporaneous quartz and emerald yields temperatures in the range of 420 to 470 °C. Combined stable isotope and fluid inclusion data are consistent with emerald precipitation at pressures ranging from 2.0 to 3.0 kbar, corresponding to depths of 5.9 to 8.9 km. Additionally, emerald channel water δD and calculated δ18O isotope values are consistent with an igneous origin for the fluids responsible for emerald precipitation; these fluids are also responsible for the metasomatization of the host rocks in and near the pegmatite, forming the phlogopite schist that is host to the Halo-Shakiso emeralds. The isotopic signatures, combined with the occurrence of adjacent pegmatites, support the classification of the Halo-Shakiso emerald deposit as a Tectonic-Magmatic-Related emerald deposit.
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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 | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".