Abstract
Visual inspection and comparison of lithological, topographical, geochemical and geophysical maps is a necessary (and often successful) way of interpreting geological features across poorly exposed or poorly explored areas. In mineral exploration, geochemical and geophysical maps are used to visually identify anomalies believed to reflect mineral occurrences. Outcropping mineral occurrences of a certain size can produce elevated concentrations of elements in stream sediment samples, or create magnetic or radioactive signals retrievable by airborne surveys. However, if the regional data are widely spaced, and if the occurrences are small or poorly exposed, the anomalies created may be too subtle to be recognised visually. In such cases, statistical data analyses may help identify deviations from background variations and trends in the data. Furthermore, visually based correlation between distribution patterns on maps is often limited to a few parameters, and multi-variable relationships are easily overlooked or not possible to deduce. Gold occurrences in Greenland occur in specific host rocks as a result of mineralising processes, e.g. hydrothermal activity, that have affected a larger area. Thus, the favourable environment for a gold occurrence may be reflected in regional scale survey data as subtle changes in certain geochemical and geophysical properties. If such changes, i.e. a multi-parameter signature for gold mineralisation, can be identified, the regional data can be searched for areas that might hold the same signature. This paper presents results gained in the application of a statistical spatial analysis method to investigate how known gold showings are expressed in a range of regional datasets from the Nuuk region, southern West Greenland. The main objective is to identify new areas with gold potential, and to quantify the signatures of the showings. The first tests based on this approach were reported in Nielsen et al. (2004) and Steensgaard et al. (2006).
Highlights
Visual inspection and comparison of lithological, topographical, geochemical and geophysical maps is a necessary way of interpreting geological features across poorly exposed or poorly explored areas
Gold occurrences in Greenland occur in specific host rocks as a result of mineralising processes, e.g. hydrothermal activity, that have affected a larger area
This paper presents results gained in the application of a statistical spatial analysis method to investigate how known gold showings are expressed in a range of regional datasets from the Nuuk region, southern West Greenland
Summary
The Nuuk region is underlain by early to late Archaean rocks dominated by quartzofeldspathic orthogneisses, but with a significant proportion of supracrustal belts, some of which contain greenstones (Fig. 1). The belts represent remnants of Archaean volcanic and associated intrusive rocks, with subordinate chemical and clastic sediments. Recent studies have revealed that the belts represent a number of individual successions formed at different locations and ages. The most common rock type is amphibolite of tholeiitic to komatiitic composition, but andesitic compositions have been recognised in some belts (Hollis et al 2005, 2006, this volume). The supracrustal rocks host several gold occurrences in association with hydrothermal alteration (Fig. 1; Appel et al 2005). At Qingaaq and Aappalaartoq on Storø (Q and A, Fig. 1) are currently targets for commercial drilling by NunaMinerals A/S
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