Beach sands and alluvial deposits are well known targets in the exploration of heavy minerals. NPA have used both Landsat and radar satellites to map not only present day drainage patterns but also palaeo-drainage and shorelines.

Using Landsat ETM data NPA have mapped several palaeo-shorelines around lake Chad in Central Africa.

Mapping Kimberlite Pipes

Kimberlite pipes are often represented topographically by shallow circular depressions. These are rarely apparent at ground level but are clearly noticeable when viewed on satellite imagery where the drainage system is likely to have a curvilinear form. They are also often associated with the intersection of extensional fault systems or on the bend of strike-slip fault systems. Although diamonds are rarely found in kimberlites the drainage systems dissipating from them can be mapped using satellite imagery.

Mapping Using RADAR

A Landsat ETM image alongside a radar image. The radar image clearly shows moisture variation related to dry river courses compared to the ETM imagery. Ancient dried up river channels (wadis), often covered by a layer of sand, are delineated much more clearly on the radar imagery. Identification of river channels helps to locate palaeo-river channels and river systems and therefore the possible location of placer deposits.

Download the pdf of this section (3.4Mb)