Basin structure on the Norwegian Margin from analysis of digitally recorded sonobuoys

Abstract

During R/V Robert D. Conrad cruise 21 a large number of sonobuoys were recorded in the Vøring, Møre, and adjacent basins at the margin off Norway. The digital sonobuoy data have been transformed into the domain of intercept time tau and ray parameter p and inverted by the tau‐sum method. To obtain better definition of the near‐seafloor velocities, using also the precritical energy, a move‐out correction has been applied to the tau‐p data. Conventional analyses of the x‐t data were also performed. In general, the various types of analyses complement each other and should be used interactively together with forward modeling to obtain the optimal velocity‐depth function. The sonobuoy results have outlined, in a regional sense, the pre‐Cenozoic sedimentary basin at the margin. This basin attains a maximum sediment thickness of 8–10 km of which only the upper half is defined by seismic reflection profiling. At the outer margin the marginal escarpments form major discontinuities in the lateral velocity distribution. The survey has proven that sonobuoy profiles recorded during standard seismic reflection profiling in major marginal basins may provide important new information, particularly about the deeper parts of the basins, that is not directly available from the reflection profiles.