Satellite Image Analysis in Mineral Exploration in Complicated Structural Terranes, Great Northern Peninsula, Newfoundland

Abstract

In April 1975, the government of Newfoundland opened large areas of crown land in northern Newfoundland to staking. Philips Management Inc., in competition with other companies, sought to establish criteria for staking. The common objective was bedded sphalerite of the Daniel's Harbour type. The sphalerite in the Northern Peninsula is associated with algal dolostones of the Upper Ordovician St. George Group. These are mostly horizontal and overlain by repetitive unmineralized limestones of the Table Head Formation. The objective of the pre-exploration program was to locate the hitherto unknown contact of the two and to stake the upper St. George Group. Landsat images at a scale of 1:1,000,000 were used in the initial rapid analysis and interpretation of a large incompletely mapped area. Four approaches were used in differentiating patterns: (1) structural where major units could be separated by outlining lineaments; (2) botanic where vegetation and snow cover were indicative of soil and rock differences; (3) geomorphic where erosional and depositional features related to relief, structure, and geology; and (4) a combination of 1, 2, and 3 where no single approach could explain a pattern or lack of pattern. The results show that the analysis of satellite images supplemented with aerial photography and existing geologic data provides for rapid and inexpensive exploration. A second more detailed image analysis using color composites (channels 4, 5, and 7) at 1:1,000,000 and 1:250,000 black and white images (channels 5 and 6) and conventional color photographs at 1:250,000 color infrared at 1:31,000 and black and white infrared at 1:15,500 was able to divide the Cambrian-Ordovician terrane into three structural regions and tentatively to reconstruct the events that had led to the formation of the Great Northern Peninsula.