NEWS

Landsat TM data can be processed in a number of different ways in order to highlight different features of interest. In geological and mineral exploration applications for example, it is important to be able to discriminate individual rock types (lithology) as well as zones where the primary lithology has been altered during the formation of ore deposits. In such instances, Landsat TM data can be processed to enhance areas of anomalously high clay and iton oxide content.

	Lithology RGB Algorithm
	Clay-Iron Ratio RGB Algorithm
	Clay Anomalism Index
	Clay Anomalism Index with Iron Oxide Threshold Anomalism (coral)

AGARSS specialises in the processing of remote spectral data, both satellite and airborne, and the production of digital indices which measure the relative content of important materials such as clay, iron oxides and vegetation. Thematic image maps, as shown, may use any one or all of these indices in combinations of red, green and blue (RGB) as specific algorithms or may density slice individual indices to display relative anomalism in a colour contoured form. AGARSS selects only those values significantly anomalous which have values greater than a threshold value. In the case shown here, Pierina, a major gold discovery in Peru, is seen to be ringed by an arc of anomalous clay and iron oxide rich material. The remainder of the area studied is relatively low in either one or the other index. This imaging technique can therefore be seen to be particularly valuable in localising areas of interest and focussing exploration effort in a regional sense. Other, more advanced spectral unmixing and classifiacation techniques can also be applied to assist in advanced exploration projects.