**6.1 Integrated interpretation of geophysical data**

### *6.1.1 Fast pseudo-geological mapping*

Geophysical surveys are essential for fast geological mapping in mineral exploration programs. Nevertheless, there is not necessarily a one-to-one correlation between geophysical responses and contrasts in lithotypes because the rockforming minerals do not entirely control geophysical properties. For example, in magnetic surveys, most magnetic anomalies are only related to the distribution of rock-forming magnetite inside the rocks. Therefore, a "geological" map created using geophysical data sets should be referred to as a "pseudo-geological" map [16]. However, the integrated interpretation of multiple data types, for example, magnetic, radiometric, conductivity, and so on, helps reduce uncertainty and acquire a more reliable geological model. SFE2D provides such an integration tool for explorations. A geological map of the exemplified region indicates a very complex geological setting along with complex structural faults and fractures (**Figure 12**).

The geophysical survey of the area is part of a regional program that aims to complete the geological mapping of the southwestern part of James Bay at a scale of 1: 50,000. The region's rocks are mainly of Archean age and belong to the Superior Province, which forms the heart of the Canadian Shield, one of the largest Precambrian cratons exposed from the terrestrial globe. There are also a number of dykes of Neoarchean to Paleoproterozoic diabase [18]. The region is subdivided into five sub-provinces, and the boundaries between the different sub-provinces are based on lithological contrasts, metamorphic, structural, and geophysical information.

However, the geological compilation is subject to varying interpretations due to intrinsic uncertainties in geoscientific data sets. This section provides an example of feature extraction for integrated geophysical interpretation through a PCA and ICA-based color image segmentation by *k*-means clustering on three sources of geophysical data sets.

*SFE2D: A Hybrid Tool for Spatial and Spectral Feature Extraction DOI: http://dx.doi.org/10.5772/intechopen.101363*

*Geology of the region. (a) Geological sub-provinces and structural features. (b) General geological map of the region. Geological data are compiled from SIGEOM [17].*

### *Mining Technology*

GGMplus Bouguer gravity data sets [19], high-resolution airborne magnetic data sets, and digital elevation model exerted from SIGEOM [17] are used as inputs for integrated feature extraction and segmentation (**Figure 13**).

The program can perform an image segmentation based on the *k*-means algorithm over the RGB-merged independent components. Unlike traditional segmentation methods, the integrated *k*-means segmentation algorithm helps calculate segments based on principal or independent components of the original data sets. The results are pseudo-geological maps that integrate extracted features from the three sources of data sets (**Figure 14a** and **b**).
