Objective domain boundaries detection in new caledonian nickel laterite from spectra using quadrant scan

Abstract

Modelling of 3D domain boundaries using information from drill holes is a standard pro-cedure in mineral exploration and mining. Manual logging of drill holes can be difficult to exploit as the results may not be comparable between holes due to the subjective nature of geological log-ging. Exploration and mining companies commonly collect geochemical or mineralogical data from diamond drill core or drill chips; however, manual interpretation of multivariate data can be slow and challenging; therefore, automation of any of the steps in the interpretation process would be valuable. Hyperspectral analysis of drill chips provides a relatively inexpensive method of collect-ing very detailed information rapidly and consistently. However, the challenge of such data is the high dimensionality of the data’s variables in comparison to the number of samples. Hyperspectral data is usually processed to produce mineral abundances generally involving a range of assump-tions. This paper presents the results of testing a new fast and objective methodology to identify the lithological boundaries from high dimensional hyperspectral data. This method applies a quadrant scan analysis to recurrence plots. The results, applied to nickel laterite deposits from New Caledo-nia, demonstrate that this method can identify transitions in the downhole data. These are inter-preted as reflecting mineralogical changes that can be used as an aid in geological logging to im-prove boundary detection.