Abstract
As part of large integrated prospecting program of the Pajala district in the northeast of Sweden a regional geochemical survey was carried out during the 1973–1974 seasons. Subsequent to the initial, fundamental studies this is the first large-scale programme by the Geological Survey of Sweden, where the technique of using organic stream sediments instead of inorganic stream sediments as a sampling medium, has been fully applied. The surveyed area totals about 8000 km 2. Mires and low productive forestland are predominant in this flat lying area (at the Arctic Circle) of the Baltic Shield. More than 10,000 samples of organic stream sediments were collected along all minor drainage channels at intervals of about 300 m. Metal contents for 25 elements were determined by X-ray and optic spectrographs on the ashed samples. The influence of the organic, Fe, Mn contents on the total metal content of each sample were corrected by stepwise regression analysis. Regionally the anomalous patterns indicate a general association of base metals to areas underlain by greenstone rocks relative to surrounding granite and gneisses. U and Mo enhancements are all located to areas underlain by formations of the Lina granite type. However, only one of the many gabbro intrusions within the area is distinguished by relatively high Cr, Ni and Co contents. In detail all of the previously known base metal occurrences have been outlined. However, as a direct result of the present survey increased prospecting attention will be focused on several new areas, where detailed follow-up studies now are planned. Of particular interest are certain graphite-bearing sections of the greenstones which display strong correlation to Cu and Ni enhancements in the organic stream sediments. A follow-up technique using bog margin samples is presented. Bog margin surveys can easily be carried out during winter and thus be of great help in maintaining continuity of work for sampling crews and laboratory personnel.
Published Version
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