The Gertrud Graben, in the Danish Central Graben, was formed during the Early Volgian by extensional block rotation. The basin was bounded by series of NW-SE trending normal faults, the resultant bathymetry of which controlled the depocenters of Volgian-Ryazanian turbidites in the Farsund Formation. Seismic correlation to basin marginal locations in the Jeppe-1 and Gwen-2 wells suggests that high amplitude horizons and high acoustic impedance values in the depocenters of the turbidites probably reflect accumulation of sand-rich turbidites. The high amplitude and impedance values, calculated from seismic inversion, are locally concentrated below minor closures. A short horizontal impedance horizon within the turbidite depocenter and below a closure possibly indicates hydrocarbon accumulation, adjacent to a well-known Jurassic source-rock the 'Hot Unit' (Bo member) in the Central Graben area. The turbidites seem to have been transported mainly from the north, possibly from positive areas in the southern Norwegian Central Graben area. Subsequent Late Ryazanian block faulting and local compressional tectonics caused erosional truncation of upper parts of the turbidites on footwall blocks, but preserved parts of the basin-axial turbidites from erosion in the hangingwall positions. (C) 2000 Elsevier Science Ltd. All rights reserved.
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