Regional and Local Structural Controls on the Distribution of Jurassic Porphyry Cu-Au-Mo and Epithermal Au-Ag Deposits in the Toodoggone District of North-Central British Columbia, Canada
Bibliographic record
Abstract
The Toodoggone district is a 100 km long and 30 km wide NNW-trending belt of mainly Jurassic volcano-plutonic island arc rocks located within the Intermontane Belt of the Stikine terrane in north-central BC. The district hosts Kemess South, the largest gold mine in BC (produced 171,600 oz Au and 23,500 t Cu in 2009), and contains several other significant calc-alkaline porphyry Cu-Au-Mo (Kemess North and Pine) and epithermal Au-Ag (Shasta, Baker, and Lawyers) deposits (Figure 1). Possible genetic linkages between porphyry and epithermal deposits in the district were investigated during a 3-year NSERC-CRD project (2004-2007) by integrating district-scale geological mapping and geochronological studies with detailed deposit models of the key porphyry and epithermal systems (Duuring et al., 2009a; 2009b). Episodic plutonism from ca. 218 to 190 Ma coincided with the formation of the largest porphyry Cu-Au (Mo) systems from ca. 202 to 197 Ma, with only minor porphyry mineralization occurring from ca. 197 to 194 Ma. Porphyry systems are spatially restricted to exposed Asitka and Takla Group basement rocks and, more rarely, the lowest member of the Hazelton Group (i.e., the ca. 201 Ma Duncan Member). These country rocks are most commonly exposed in the southern half of the district where high rates of erosion and uplift have resulted in their preferential exposure. In comparison, low- and high-sulfidation epithermal systems are more numerous in the northern half of the district, where younger overlying Hazelton Group rocks are mainly exposed. High-sulfidation epithermal systems formed at ca. 201 to 189 Ma, whereas low-sulfidation systems developed at ca. 196 to 186 Ma, demonstrating a temporal coincidence with porphyry systems elsewhere in the district. Historically, most low-sulfidation epithermal systems in the Toodoggone district were considered to be unrelated to porphyry systems. Rather, these deposits were interpreted
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.005 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".