Gold exploration using till at Petäjälehto, northern Finland

Abstract

ABSTRACT Till geochemistry, ground geophysics, heavy mineral studies and diamond drilling have been used for gold exploration at the Petajalehto target, northern Finland. Geochemical anomalies of gold and its pathfinders Cu, Bi, Co and Te in detailed till sampling have encouraged further exploration at the target scale. In addition, tens of Au nuggets in heavy mineral concentrates of basal till and in pre-Quaternary regolith indicate significant Au mineralization in the target area. Preliminary lithological studies based on the outcrop observations and drill-cores proved the hydrothermally altered, brecciated shear zones in granite gneiss and amphibolite host rocks to be suitable for Au mineralization. The source for Au nuggets seems to be the quartz–carbonate and magnetite–pyrite–quartz veins. This research also strengthens the concept of effectiveness of surficial geological methods for tracing potential sources of mineralized debris and rock fragments in glaciated terrains.