Geochemistry
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Anomaly Identification  

In this study, the 99th percentile was used to classify samples as "enhanced" in any element for the purposes of a MineMatch description. Select from the following links to view tables showing these thresholds in the format of your choice. Thresholds were calculated for the sample population as a whole, as well as for each lithology individually.

  • PDF format listing of thresholds
  • PDF format listing of numbers of samples in each lithology population
  • Web page (HTML format) showing all lithologies, thresholds, and sample populations
  • Excel Spreadsheet with locked lithology column and column headers showing lithologies, thresholds and sample populations. [This requires that the (free) MS Office
    Web Components (16 Mb) are installed on your computer.]

MineMatch reports for each Anomaly Cluster list the anomalous elements which characterise the cluster, and include, in the "Comments" column of the report, a statement as to whether the element is anomalous within the entire population, the lithology-specific population, or both populations.  (See examples of each explanation in the graphic above.)

  • Steve Amor has written a good overview of geochemical data presentation and interpretation for exploration, which includes a discussion of the advantages of using percentiles to set anomaly thresholds.  It is available for download in summary <362Kb> and complete <1.9Mb> form.
Regional Silt Geochemistry Statistics  

A large number of statistical graphics have been prepared to assist with the interpretation of the stream sediment data used in this study, and to support the use of the 99th percentile as the threshold above which to regard a sample's analytical result as "anomalous" or, in MineMatch terminology, "enhanced".

A special web page has been designed to facilitate the comparison of data sets, by lithology, analytical method, or element, using constant horizontal and vertical plotting scales when appropriate.

To view these graphics, please click here.

These plots are likely to be of value beyond the scope of target generation in minerals exploration. Environmentalists will be interested in the information they provide about stream compositions. Bedrock mappers will be interested in the extent to which they validate lumping and splitting of rock types into different mappable lithological units at a scale of 1:250000.

  • To compare the geochemistry of lithologies mapped in the Yukon with lithologies mapped in neighbouring British Columbia, please click here.
  • The GERM geochemical reservoir database  provides a wealth of reference data which is downloadable in many formats, and which is useful of comparison with the data reported in this study.
Thresholds by Lithology

In this study, the 99th percentile was used to classify samples as "enhanced" in any element for the purposes of a MineMatch description. Select from the following links to view tables showing these thresholds in the format of your choice. Different thresholds were calculated for each lithlology.
 

  • PDF format listing of thresholds
  • PDF format listing of numbers of samples in each lithology population
  • Web page (HTML format) showing all lithologies, thresholds, and sample populations
  • Excel Spreadsheet with locked lithology column and column headers showing lithologies, thresholds and sample populations. [This requires that the (free) MS Office
    Web Components (16 Mb) are installed on your computer.]
 
Anomaly Cluster Geochemical Details

The Anomaly Cluster Details report provides RGS sample compositions for anomalous samples, together with 99th percentile thresholds (lithology and non-lithology-specific), and the number of samples present in each sample population.

Click here to view Anomaly Cluster Details reports.

Advice on how to use the report, and associated information, is presented in the opening screen, as shown on the right (click to enlarge).

The report has been carefully formatted for letter-size printing, using red, bold and underlining to highlight anomalous values.

By clicking on the "Find" icon in the report (a magnifying glass near the top left corner), Anomaly Clusters may be queried by any combination of input variables. Use the "help" facility on the Report page (the button with a question mark near the top left corner) to find out more about how to use this very powerful querying feature.

For example, you can search for all Anomaly Clusters which have Ni_INA_ppm >= 260 and Zn_AAS_ppm >= 2200, as illustrated in the figure on the right (click to enlarge).

 

The first cluster satisfying your query should be Cluster No 1085, which is also anomalous in Ba and Mo  -  as shown in the figure on the right (click to enlarge).

                                                                Contact geology@gov.yk.ca with questions or comments about this web site.
                                                                                                                  Copyright 2004 Georeference Online Ltd
                                                                                                                                              Last modified: 11/10/04