Surface magnetic anomaly study on the eastern part of the Forlandsundet Graben

Abstract

A surface magnetic survey was carried out by use of a proton magnetometer over wide strandflats along the eastern coast of Forlandsundet, western Spitsbergen, to decipher subsurface structures and lithologies. Distinctive linear high-anomaly segments and zones were recognised on the magnetic anomaly maps. These zones coincide well with the eastern marginal fault of the Tertiary Forlandsundet Graben and associated faults north of St Jonsfjorden, while they reflect bedrock lithologies in the south. The high-anomaly segments, which constitute the zones, are locally aligned in a left-stepping, en echelon arrangement within the zones, indicating a dextral transpressional stress regime on the eastern marginal fault of the graben during a certain time. Sudden termination and bends of the segments define a later transverse fault system.