Petrogenesis of the ferrogabbroic intrusions and associated Fe-Ti-V-P mineralization within the McFaulds Greenstone belt, Superior Province, Canada
Bibliographic record
Abstract
The McFaulds Lake area (commonly known as the Ring of Fire), has been the site of \nmuch recent exploration within northern Ontario. The area represents a recently discovered \nArchean greenstone belt which is host to world class chromite deposits along with significant \nCu-??Zn VMS, magmatic Ni-??Cu-??PGE and Fe-??Ti-??V occurrences. Much emphasis has been placed on \nthe chromite mineralized ultramafic intrusions with little attention focused on the Fe-??Ti-??V \nmineralized ferrogabbroic intrusions. \nThe Butler and Thunderbird intrusions represent the best described intrusions within \nthe volumetrically significant ferrogabbroic suite within the McFaulds Lake area. These \nintrusions are characterized by a suite of well layered magnetite-??ilmenite rich rocks which are \ndominantly composed of gabbroic to anorthositic units with lesser stratigraphically \nconformable units composed of pure magnetite-??ilmenite. The Fe-??Ti oxide rich layers contain \nvariable vanadium mineralization and low chromium contents within magnetite (up to 2.45 \nV2O5 wt. %, 0.99 % Cr2O3 wt. %) and ilmenite (up to 0.57 V2O5 wt. %). The massive and semi-?? \nmassive oxide layers occur as basal members of repeated cycles characterized by sharp lower \ncontacts which grade upwards into oxide-??rich pyroxenite, followed by oxide-??bearing \nleucogabbros and/or anorthosites. The layers are believed to be caused dominantly by \nmagmatic convection currents within a system which is at least partially open to oxygen. No \nevidence has been found to suggest multiple pulses of magma. Oxide-??silicate liquid \nimmiscibility is thought to only occur within the evolved, apatite-??bearing margins of the \nThunderbird intrusion; however, additional drilling may reveal further apatite mineralization. \nThe ferrogabbroic intrusions are thought to have originated from a shallow depleted \nmantle source, possibly related to a plume event. The ferrogabbros have likely undergone a \ntwo stage differentiation to account for the extreme iron enrichments. The first stage is \ncharacterized by an anhydrous, tholeiitic melt, within the upper mantle (above the garnet \nstability field, <110 Km) which underwent Fe-??Ti enrichment due to the crystallization of Fe-?? \npoor phases (e.g., olivine, plagioclase, etc.) within a system closed to oxygen. The second stage \nis considered to be a very shallow intrusion within the McFaulds Lake mafic-??felsic volcanic \nrocks. This final stage is characterized by a system which was at least partially open to oxygen \nfrom an originally reduced magma (<QFM buffer). These magmas initially crystallized Cr-??V-??rich \nmagnetite-??ilmenite horizons and gradationally evolved into Cr-??V-??poor, apatite-??bearing \nferrogabbros. These ferrogabbros likely share a parental magma with the coeval Cr-??Ni-??PGE-?? \nbearing ultramafic intrusions of the McFaulds Lake greenstone belt. Additionally, spatial and \ngeochronological evidence suggests that abundant VMS-??style mineralization within the \nMcFaulds Lake area may be a result of a thinned lithosphere during plume tectonics.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| 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 teacher head, 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".