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Geostatistical investigation of the Kutcho Creek chrysotile deposit, Northern British Columbia

  • A. J. Sinclair
  • L. J. Werner
Article
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Abstract

The Kutcho Creek asbestos deposit, owned by Cassiar Asbestos Corporation Ltd., has been sampled by two major exploratory programs that have provided two sets of grade data—one from the horizontal direction (wall readings) and one from the vertical direction (diamond drill cores). These data (percentage chrysotile by volume) were divided into well-defined groups on the basis of location and sample continuity, and experimental variograms for percentage of fiber content were calculated for each group. Horizontal data were all oriented in directions roughly parallel to the trend of an elongate serpentinite zone containing local centers rich in chrysotile veinlets. Spherical variogram models fitted to horizontal and vertical data sets are as follows: Vertical:
$$\begin{gathered} \gamma (h) = 0.27 m^2 + 0.44 m^2 [(3h/70) - (h^3 /85,750)] h \leqslant a \hfill \\ \gamma (h) = 0.71 m^2 h \geqslant a \hfill \\ \end{gathered}$$
Horizontal:
$$\begin{gathered} \gamma (h) = 0.27 m^2 + 1.20 m^2 [(h/60) - (h^3 /729,000)] h \leqslant a \hfill \\ \gamma (h) = 1.47 m^2 h \geqslant a \hfill \\ \end{gathered}$$
Wherem is the mean value of data used in the construction of a variogram,h is a lag (sample spacing), anda is the range over which the grade is autocorrelated. These two one-dimensional models can be combined to a two-dimensional model with the form γ(h)=γ(r)+γ(x) where γ(r) is an isotropic component (equivalent to the vertical model above) and γ(x) is a zonal component in the horizontal direction (equivalent to the difference between the horizontal and vertical models above). This general model describes data throughout the entire serpentinite zone in a satisfactory manner but, of course, does not contain information in the third dimension, and, thus, cannot be used as a basis for grade and tonnage calculations and corresponding error estimates. Nevertheless, the analysis has illustrated the potential of variogram analysis for such tonnage and grade calculations. Furthermore, the study has provided limiting two-dimensional information on the geometry of chrysotile-rich zones within the serpentinite belt, information that can be used to advantage in planning future exploratory drilling.

Key words

geostatistics mining geology 

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References

  1. David, M., 1977, Geostatistical ore reserve estimation; Developments in Geomathematics 2, Elsevier, Amsterdam, 364 p.Google Scholar
  2. Gabrielse, H., 1962, Cry Lake Map Sheet 104 I, Geological Survey of Canada, Map 29.Google Scholar
  3. Huijbregts, C., 1971, Reconstitution du variogramme ponctuel a partir d'un variogramme experimental régularisé, Report N-244, Centre de Morphologie Mathématique, Fontainebleau, 22 p. and three graphs.Google Scholar
  4. Serra, J., 1968, Les structures gigogne: morphologie mathématique et interpretation metallogenique; Mineral. Deposita, v. 3, p. 135–154.Google Scholar
  5. Sinclair, A. J., and Deraisme, J. R., 1974, A geostatistical study of the Eagle copper vein, Northern British Columbia, Bulletin of the Canadian Institute of Minerology and Metallurgy v. 67, p. 131–142.Google Scholar

Copyright information

© Plenum Publishing Corporation 1978

Authors and Affiliations

  • A. J. Sinclair
    • 1
  • L. J. Werner
    • 1
  1. 1.Department of Geological SciencesUniversity of British ColumbiaVancouverCanada

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