Bottom-up mineral exploration: ore-element upgrading in the upper mantle and tools for its discovery
Bibliographic record
Abstract
Mineral exploration targeting typically focuses on the critical pathways and depositional traps of ore systems. The role of pre-enriched source regions on ore deposit genesis is unclear, particularly for systems that involve significant transport of ore components (e.g. Au). Because Au is suggested to be derived from the mid- to lower-crust and/or upper mantle at orogenic deposits, it is not surprising that the deepest and most inaccessible parts of this ore system is also the least studied and understood. Herein we address that knowledge gap by studying the upper mantle directly, using examples of young ophiolitic mantle (Atlin, British Columbia) and ancient cratonic mantle (Superior craton, Ontario; Slave craton, Nunavut). Project results demonstrate two dominant mechanisms for Au upgrading in the lithospheric mantle: (1) base metal sulphide precipitated during melt:rock reactions between peridotitic residues and asthenospheric melts, and (2) hydrous, fluid-inclusions trapped after release from subducting slabs. The remelting of such pre-enriched metasomatized mantle has been previously proposed as a viable source for a variety of ore systems (e.g. mafic to ultramafic rock-hosted platinum-group element deposits). Mapping the architecture of these deep lithospheric metasomatized mantle domains and their association with rising asthenospheric melts is of significant interest for mineral exploration. New geochemical methods and data processing completed as part of the current study, coupled with advances in geophysical imaging, provide additional tools for mapping these pre-enriched lithospheric mantle domains at depth.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".