An introduction to the interpretation of data from central Baffin Island, district of Franklin

Abstract

Results from Jake sediment and water geochemical survey of 26 000 km2 of Baffin Island are shown on 1:2 000 000 colour maps, accompanied by discussions on lithology, minerai deposits, and surface environment. The maps are supplemented by maps of bedrock geology, metamorphic geology, glacial geology, gravity, and aeromagnetics. The area, part of Foxe Fold Belt, comprises Aphebian supracrustal rocks, bounded to the north and south by Archean terranes. Within the Foxe Fold Belt there are strong base metal and arsenic anomalies in Jake sediments. The base metal anomalies are the product of high element contents in some lower Piling metasediments (quartzite, marble, dolomite, sulphidic schist, iron-formation, mafic volcanics) and favourable present-day conditions for anomaly formation. The schist and iron-formation have high metal contents, presumably from volcanic-exhalative activity. Recent oxidation of sulphidic schists produces acidic water that dissolves base metals, which are then precipitated in Jake sediments. Where water passes from acidic schist to alkaline marble and dolomite, there is strong precipation of base metals. The mineral potential of these metalliferous metasediments is unknown. They are correlated with rocks hosting the Sorte Engel lead-zinc deposit on West Greenland. Upper Piling turbidites that form the axial portion of the fold belt host intense lake sediment anomalies for arsenic. Because of the gold-arsenic-turbidite-association, further investigation is warranted. Archean granite-gneiss terrane north of the fold belt has been subdivided into blacks based on geochemical variation in lake sediments. Base metal anomalies probably relate to metamorphosed volcanics. Hudsonian granitoids and Archean gneiss along the northern boundary of the fold belt form a strongly anomalous zone for uranium.