The application of till geochemistry in exploration in the Rogen moraine area at Petajavaara, northern Finland

An incoherent hydrothermally altered Cu- and Au-bearing shear zone has been discovered as a result of till geochemical exploration in the Petajavaara site, northern Finland. Aerial photo interpretation, tractor excavations wi th sampling and analysis of earlier percussion drilling samples are the met hods used in the study of Quaternary geology and till geochemistry. The bed rock in the Petajavaara site is composed of quartzite, basic volcanic rocks and diabase dykes as part of the Perapohja Schist Belt. particular moraini c landform types are ground, cover and Rogen moraines, of which the Rogen m oraines take the form of a series of N-S ridges containing two separate til l beds. A generalized model for the Au distribution in till at the Rogen mo raine area is presented. Surficial parts of Rogen moraine ridges are the mo st significant for ore exploration. The local provenance of the material an d high Au contents in the C horizon of the upper till bed are characteristi c. (C) 2000 Elsevier Science B.V. All rights reserved.