Emplacement of Sulfide Deposits in the Copper Cliff OffsetDike during Collapse of the Sudbury Crater Rim: Evidence from Magnetic FabricStudies
Bibliographic record
Abstract
Quartz diorite offset dikes in the country rocks surrounding the 1.85 Ga Sudbury impact structure were emplaced within fractures formed during hypervelocity impact, providing conduits for the injection of quartz diorite impact melts. The offset dikes host major Ni-Cu-PGE deposits, with the radial Copper Cliff dike hosting ~15 percent of the known Sudbury ore. The anisotropy of magnetic susceptibility of the Copper Cliff dike was studied to determine the nature of the fabrics that developed during emplacement of the quartz diorite and the associated sulfide bodies. The anisotropy of magnetic susceptibility reveals a predominantly northwest-southeast-striking, steeply dipping foliation and a steeply northwest- to vertically plunging lineation. The foliation along both the eastern and western sides of the dike is counterclockwise-oblique to the north-south to north-northwest–south-southeast-striking, vertically dipping dike margins. The magnetic fabrics in the dike are consistent with a component of strike-slip displacement during emplacement of the quartz diorite melt. The data are interpreted to indicate that the Copper Cliff dike acted as a melt-lubricated dextral transfer fault during collapse of the inferred inner rim of the central peak ring to accommodate ultra-high strain rate displacements on previously documented pseudotachylite-rich normal fault zones. Collapse may have caused injection of sulfide-rich melts into the Copper Cliff dike leading to the formation of Cu-Ni-PGE deposits. Collapse of the inner rim of the central peak ring is thought to have occurred too soon after the impact to allow for fractionation of the sulfides from the impact melt sheet. Therefore, it is suggested the sulfide-rich impact melts were derived principally from the target rocks.
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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 | 0.002 | 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) | 0.002 | 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".