Mineral exploration and environmental applications of lake sediment geochemical mapping in the Canadian Cordillera
Bibliographic record
Abstract
In much of the Canadian Cordillera, stream sediments are the standard sampling medium for reconnaissance scale geochemical surveys, and in British Columbia, Regional Geochemical Surveys (RGS) conducted over the past 20 years comprise some 43,000 sites covering a large proportion of the province. Organic-rich profundai lake sediments are, however, a more appropriate geochemical medium in the northern Interior Plateau, a region of subdued topography and an abundance of lakes in the central part of the Cordillera within British Columbia, where stream sediment geochemical methods are limited by a paucity of active sediment in drainage channels. Mineral exploration here has historically been impeded by extensive drift and forest cover, poor bedrock exposure, a barren Tertiary volcanic cover and, until recently, relatively low-resolution geological mapping. Lake sediment geochemistry is based on the detection of metals which are liberated from rock, till or other material during weathering, and subsequently transported to and bound in organic-rich lake sediments. It can be an effective tool to delineate regional geochemical patterns and anomalous metal concentrations related to mineral deposits ( Hoffman 1976 , Coker et al. 1979 ) in central British Columbia, and since 1993 the British Columbia Geological Survey Branch (GSB) has been conducting regional lake sediment geochemical coverage of this region ( Fig. 1 ). The objective of these surveys is the development of a high-quality geochemical database suitable for mineral exploration, resource assessment and environmental studies. Currently, most work has been concentrated in the Nechako and Fraser Plateau regions of the Interior Plateau, where survey results have been successful in helping stimulate and focus mineral exploration. Its environmental application in assessing concentrations of elements detrimental to human health or to that of fish, wildlife or livestock, has been less clear. The objective of this paper is to outline the usefulness of regional lake sediment geochemical surveys in this part of the Cordillera, focusing on its applicability as a geochemical mapping medium in identifying lithological variations in underlying bedrock; mineral exploration; and environmental assessment. Figure 1 Map showing locations of regional lake sediment geochemical surveys conducted in the Nechako and Fraser Plateau areas of the Interior Plateau (dotted line) in central British Columbia. Locations of examples cited in text: (1) and (3) Pinchi Lake area, and (2) Tommy lakes area are outlined in bold. Outline of Interior Plateau after Holland (1976 ). Parsnip River map area (NTS 93) outlined; letters in map indicate its component 1:250,000 map areas. A map of central British Columbia, Canada, showing lake sediment survey areas conducted between 1983 and 1996, with key cities and regions labeled. https://www.w3.org/1999/xlink" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003761259/8b43f88f-68ae-41db-a20d-72c98ffc38e5/content/pg178_Image_48.tif "/>
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.004 | 0.007 |
| 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) | 0.002 | 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".