Multiscale hierarchical domaining and compression of drill hole data

• Geochemical analyses have been collected from mineral exploration drill holes.
• A wavelet transform is applied to the data in order to detect lithological boundaries.
• A rectangular tessellation is applied to the scale–space plot of the transform.
• The tessellation can be filtered to remove noise and unwanted variation.
• The filtered tessellation provides a multiscale lithochemical log.

New drilling methods, currently under development for minerals exploration, combined with rapid data collection by a range of sensors means that the end-user is confronted with increasingly large data sets. In order to reduce the stream of data into objects which represent meaningful geological features we need to incorporate spatial information into the analysis. Boundary detection incorporating multiscale considerations has previously been carried out using a scale–space plot from a wavelet transform. We present a method which applies a rectangular tessellation to the wavelet transform, this has the advantage of being easier to interpret, as it resembles a geological log. In addition, the tessellation records hierarchical information for different scale objects. The tessellation can be filtered in order to remove unwanted variation (including noise) from the results. When applied to geochemical data, the resulting tessellation provides a basis for classification of lithochemical units that is more reliable than classification by considering individual samples without spatial context.

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