2-D and 3-D Trend Analysis - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 273

Fig. 7.33 Crest-lines for selected phase maps of copper and gold occurrences (Source: Agterberg
1974 , Fig. 82)

of the chi-square distribution with four degrees of freedom (cf. Agterberg and
Fabbri 1973 ). A similar procedure was followed for gold deposits in the same
area. Relatively large P -values (with period

20 miles) at some distance from the
origin were selected and marked as dots in Fig. 7.32a, b . Most of these are
accompanied by a contoured maximum. Directionally, these dots form small
clusters of which there are three for copper and two for gold. The crest-lines of
the three (N-S, E-W and SE-NW) copper clusters and the large (SW-NE) gold
cluster are shown in Fig. 7.33b . These sets of lines tend to intersect at the same
points. Agterberg and Fabbri ( 1973 ) speculated that patterns of lines indicating
larger concentrations of copper and gold deposits may be useful for extrapolation
into parts of the Abitibi area where bedrock is hidden because of relatively thick
glacial cover.

References

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Agterberg FP (1966) Trend surfaces with autocorrelated residuals. In: Proceedings of the sympo-
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University , pp 764-785
Agterberg FP (1968) Application of trend analysis in the evaluation of the Whalesback Mine,
Newfoundland. Can Inst Min Metall 9:77-88
Agterberg FP (1969) Interpolation of a really distributed data. Q Colo Sch Mines 64(3):217-237
Agterberg FP (1970) Autocorrelation functions in geology. In: Merriam DF (ed) Geostatistics.
Plenum, New York, pp 113-142
Agterberg FP (1974) Geomathematics. Elsevier, Amsterdam
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models. Reidel, Dordrecht, pp 147-171