Residual gravity anomalies reveal basement grain and structural elements of the Vøring Margin, off Norway

Berndt, Christian. 2002 Residual gravity anomalies reveal basement grain and structural elements of the Vøring Margin, off Norway. Norwegian Journal of Geology, 82. 283-288.

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Abstract/Summary

Free-air gravity data from satellite altimetry and ship-track derived bathymetry data are used to calculate a residual Bouguer gravity anomaly map for the mid-Norwegian Margin. The anomalies were corrected for a density difference between basin sediments and water of 1400 kg m-3 and filtered for wavelengths between 10 and 190 km. A comparison of seismic and magnetic information about the crustal structure corroborates previously identified structural elements and reveals some additional complexity in the margin structure. The strongest negative anomalies relate to the Hel Graben and the Rås Basin indicating that these synclines are deep sedimentary basins. The strongest positive anomalies occur on the Sandflesa High, and the Utgard High and on two segments of the Gjallar Ridge. They relate to metamorphic core complexes and/or basement highs. The gravity anomalies show two regional strike directions, which are presumably associated with Tertiary extension and older weakness zones in the basement. Within the investigated wavelength, residual Bouguer gravity anomaly maps derived from satellite altimetry and ship-track bathymetry are as suitable for investigating regional trends as maps derived from ship-track gravity measurements. Thus, these residual gravity maps provide a powerful aid for seismic interpretation of deep crustal structures.