2-D and 3-D Trend Analysis - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 267

Fig. 7.26 Manually contoured map of moving-average data for gold in inch-dwt (After
unpublished map by Prof. D.G. Krige; also Fig. 1 in Whitten 1966 ). Each value of 50-ft. grid is
average for enclosing 100 100 ft. cell; outline for subarea selected for harmonic analysis
(Source: Agterberg 1974 , Fig. 75)

7.4.2 Whalesback Copper Deposit Exploration Example

Figure 7.28 shows a longitudinal cross-section of the Whalesback deposit, New-
foundland. It contains the intersection points of 188 underground drill-holes with
the central part of the ore zone. The average copper value was calculated for each
hole over the width of the orebody. This value was multiplied by horizontal width
yielding so-called percent-foot values contoured by mining staff. The central part of
this diagram shows a relatively rich copper zone that dips about 45 downward to
the west. The mining grid was previously used for location in Figs. 7.8 and 7.9 .
The array of Table 7.4 , which was based on Fig. 7.28 , was enlarged to size
(32 32). 2-D autocorrelation function and power spectrum are shown in

Figs. 7.29 and 7.30 . Both diagrams illustrate the strong zoning in the deposit. The
central copper zone is flanked by two elongated minima and at about 460 ft. from it
there occur two other relatively copper-rich zones, although their maxima are not as
high as that for the central zone. The following experiment indicates that harmonic
analysis can be an excellent exploration tool in a situation of this type.
Development of the Whalesback copper deposit was performed in two different
stages. Copper percent-foot values from the first surface boreholes are shown in
Fig. 7.31b . There are only 20 exploration values, which are irregularly distributed.
The question can be asked of how the pattern of Fig. 7.28 , which is based on 188 more