Catchment Analysis Applied to the Interpretation of New Stream Sediment Data from Northern Vancouver Island, British Columbia
(102I and 092L)

- D. Arne and O. Brown, CSA Global Canada Geosciences Ltd.

The terrain of northern Vancouver Island is considered ideal for the automated generation of catchment basins, which help define the zone of geological influence on a specific stream sediment sample site. For this reason, this project is using stream sediment data collected as part of the Northern Vancouver Island Exploration Geoscience Project, a partnership between Geoscience BC and the Island Coastal Economic Trust.

New map products will be produced, adding value to existing stream sediment datasets by providing additional information not readily available to most prospectors and geologists working for small exploration companies. It is hoped that these new maps, their release anticipated for early 2015, will encourage further mineral exploration on northern Vancouver Island.

Posters and Presentations
2015: Catchment Analysis Applied to the Interpretation of New Stream Sediment Data, Northern Vancouver Island, Canada - KEG 2015 Conference presentation (pdf, 3.4 MB)

2015: Catchment Analysis Applied to the Interpretation of New Stream Sediment Data from Northern Vancouver Island (NTS 102I and 92L) - Mineral Exploration Roundup Poster (pdf, 5.6 MB)
Technical Articles
2015: "Catchment analysis applied to the interpretation of new stream sediment data from northern Vancouver Island, British Columbia"
- Summary of Activities 2014, Report 2015-1 p. 41-46 (pdf, 1.8 MB)

Final Deliverables
Geoscience BC Report 2015-04
Catchment Analysis Applied to the Interpretation of New Stream Sediment Data, Northern Vancouver Island, Canada (NTS map 102I and 92L)

Raw copper data in stream sediment samples obtained from moss mats on Northern Vancouver Island are dominated by the presence of mafic volcanic rocks of the Karmutsen Formation and, to a lesser extent, by the presence of diabase sills of the Mount Hall Gabbro. These units can effectively be traced using the first principal component from multivariate analysis of the raw geochemical data. High background copper in these lithological units potentially obscures copper anomalies associated with exposed copper deposits in the region.

By examining previously published geochemical data from 1725 samples from Northern Vancouver Island, and using copper as the demonstration element, this study illustrates that there are a variety of ways to process raw copper data in areas strongly influenced by a particular rock type. Nested catchments for the samples were delineated automatically from digital elevation data using a procedure developed by the B.C. Geological Survey.

A limited number of map products are included in this report, designed to illustrate the relative effects of different data processing options for copper. Digital data files that accompany this report contain the catchment polygons as well as the leveled and residual data for a number of elements.

 


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