The Edison magnetite deposits in the context of pre-, syn-, and post-orogenic metallogenesis in the Grenville Highlands of New Jersey
Bibliographic record
Abstract
Most of the magnetite deposits of the eastern Grenville Province have been described as precipitates from hydrothermal solutions derived from metamorphic processes, from early, late, or post-Grenville granites, or as metasediments. Granites host many of these deposits, but others, including the historic Edison iron mines of New Jersey, are hosted by potassium-feldspar gneiss, commonly interpreted as meta-arkose. Our new geochemical data indicate, however, that the protolith of the potassium-feldspar gneiss is rhyolite, not arkose. Supporting evidence includes (i) the absence of an underlying potassic provenance for arkosic sediment, (ii) potassium and sodium contents among host rocks that exceed the range of arkose but are consistent with A-type rhyolite, and (iii) a close chemical resemblance of the potassium-feldspar gneiss to an A-type granite (Byram granite) that is closely associated in time and space. As the ore zone through the Edison mines is approached, the K/Na ratio of the host rocks undergoes a distinct increase, consistent with extensive diagenetic alteration of rhyolitic pyroclastics in a hypersaline environment. This alteration provided a local ligand source for subsequent hydrothermal iron mineralization derived from the nearby pre-orogenic Byram granite. These iron concentrations were then remobilized and recrystallized during subsequent Grenville metamorphism. Although some of the magnetite deposits of the New Jersey Highlands display evidence of post-orogenic replacement and an association with undeformed pegmatites, the banded magnetite ore and related pegmatites of the Edison mines are conformable to the foliation of the host rock and are interpreted as metamorphic products of pre-orogenic, granite-derived, hydrothermal iron concentrates.
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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 | 0.001 | 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".