Combined magnetic, electromagnetic and resistivity study over a highly conductive formation in Orrivaara, Northern Sweden.

ABSTRACT Different geophysical methods were used to determine the characteristics of a highly conductive structure in Northern Sweden, first discovered on airborne data. Airborne electromagnetic (very low frequency) data indicate a high conductivity structure coincident with low magnetic patterns. The airborne data were processed in different ways to enhance various structures/features. In particular we introduce a new transformation to current density that is suitable for delineating conductive structures. Ground measurements of the total magnetic field, radiomagnetotelluric measurements and resistivity imaging provided valuable information that was used in the compilation of a new bedrock map over the area. The results of our measurements indicate that the conducting structure consists of metasedimentary rocks containing thin horizons of pyrrhotite and graphite. [ABSTRACT FROM AUTHOR]