Interpretation of geophysical data from Spitsbergen: Structure of the basement and implication for regional geology.

New Arctic aeromagnetic data from Spitsbergen, Svalbard Archipelago, have been interpreted. The depths to the top of the magnetic source rocks have been interpreted using profile data, and the interpretation shows that the magnetic basement is deeper than 3 km below sea level over large areas. A picture of basement horsts and grabens emerges from this map. A deep N-S trending trough, more than 8 km deep, exists beneath Isfjorden. It has a graben structure and is bordered to the east by a southward extensions of the Billefjorden Fault Zone. Model Calculations show that steep east-dipping structures in the pre- Devonian Hecla Hoek basement rocks can explain anomalies above the Bille- fjorden Fault Zone. The Billefjorden Fault Zone is Interpreted to extend from the shelf north of Spitsbergen to south of Isfjorden and may extend southwards into the Barents Sea. A new aeromagnetic map covering Spitsbergen and the Adjacent northern Barents Sea has been compiled which shows that struc tures on Spitsbergen continue far into the Barents Sea. Some of the anomalies that originate within the crystalline basement occur near the boundaries to younger sedimentary basins and suggest that basement tectonics have influenced basin formation.

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