Baseline geochemistry and controls on mine drainage composition in the Bridge River Mining District, British Columbia
Bibliographic record
Abstract
Without appropriate environmental management controls and regulatory oversight, the mining and milling of gold (Au) can result in significant risks to the environment and human health. Orogenic lode Au deposits, hosted mainly by quartz-carbonate veins, occur in deformed greenstone and metasedimentary terranes around the world. These deposits are the main source of Au in Canada, and are presently a key focus for exploration and development. This Open File Report summarizes results from a three-year environmental geochemistry and mineralogy study of past-producing Au deposits in the Bridge River Mining District in British Columbia. From 2006 to 2008, samples of stream water, sediment, waste rock, tailings, and mine drainage were collected from the Bridge River District, including the Bralorne, King, and Pioneer Au mines near Bralorne, BC. Together, these three mines represent the largest historical Au producer in the Canadian Cordillera (> 4.15 M oz. between 1932 and 1971). Samples were also collected from several nearby antimony (Sb) and mercury (Hg) deposits, which may represent the epizonal portions of the Bralorne-Pioneer hydrothermal system. Baseline concentrations of As, Sb, and Hg in stream sediments from the Bridge River District range from 0.6-168 mg/kg, 0.1-8.3 mg/kg, and 9-1010 µg/kg, respectively. The distribution of these elements is strongly controlled by the original pattern of hydrothermal mineralization within the district. Historical tailings and sediments from underground mine workings have much higher concentrations of As (7.4-137,000 mg/kg; median, 3300 mg/kg), Sb (0.3-707 mg/kg; median, 12.6 mg/kg), and Hg (49->100,000 µg/kg; median, 1200 µg/kg). The highest Hg concentrations occur in tailings at former mill sites where Hg was used for Au amalgamation, and in stream sediments at an abandoned Hg mine. Baseline concentrations of As, Sb, and Hg in filtered stream waters throughout the district ranged from 0.1-4.5 µg/L, 0.03-0.43 µg/L, and 0.6-4.1 ng/L, respectively. Dissolved concentrations of As and Sb were typically much higher in waters draining from mine workings, whereas Hg concentrations were relatively low (<12 ng/L) in all waters sampled. Drainage from the main portal of the Bralorne Mine contains high concentrations of As (2250-2560 µg/L) derived from the flooded mine workings, and this study provides new information on the key processes controlling the composition of this mine effluent. The results of this research can be used to better understand the environmental characteristics of orogenic lode Au deposits, and help to minimize the environmental impacts associated with Au extraction.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.006 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".