Structural Interpretation of Territories

Map of Structural Interpretation
in Northern Ontario

Structural interpretation of remote sensing data (satellite images, airborne photo images, or a combination of both) is very useful for the determination of single kimberlites/lamproites or their clusters within local areas, which are already selected either by an ‘Area Selection’ process or from other data (i.e., finds of diamonds or indicator minerals).

In the first stage, all lineaments, within the selected area, are identified, grouped, classified by their orientation, relative age, and their role in the   kimberlite emplacement. The lineaments can be identified by boundaries of polygonal lake depressions, chains of lakes, sharp changes in photo-tone, step bends and benches on slopes, scarps and joints in bedrock massifs and narrow, extended shaded features visible in the photos.  As a result, the most favourable for kimberlite/lamproite/lamprophyre zones and lineaments are identified.

At the second stage, we use our original programs for compiling special maps, such as Lineament (jointing) Density Map, Tensile Stress Concentrators Map and others.  Lineament (jointing) density is directly proportional to the permeability of the Earth’s crust, i.e. to the ability of kimberlites to penetrate the Earth’s crust through to the surface.  We estimate the lineament density using a square grid with grid intersections spaced ~1 km apart.  The initial matrix can be counted as ‘lineaments per one square kilometer’.  Having done this, we obtain the lineament density distribution in any study area. We usually compile additional maps, such as rose-diagram distribution map and others, if necessary.

Kimberlitic pipes (dark spots)
in airborne photo image

Sometimes, kimberlite pipes can be identified in   airborne photo images. According to our experience in Russia, approximately 7 % of identified kimberlites in the Siberian Province were found using conventional airborne photo images at 1:60,000 – 1:20,000 scales (Kaminsky et al., 1999).

As a result, local areas (or individual kimberlites/lamproites) are identified and classed by their prospectivity for kimberlite pipes. Combined with the results of geophysical interpretation (or independently of them), our results will help to localise drill targets.