Paleogene sequence stratigraphic framework of the Faeroe Basin

Abstract

During Paleogene times up to 15 000 ft (4570 m) of clastic sediment was deposited in the Faeroe Basin, north of the Shetland Islands. A sequence stratigraphic study has shown that the Paleogene deposition in the Faeroe Basin was cyclic with prominent basinward and landward shifts in sedimentation. The correlation of major unconformity surfaces allowed the section to be subdivided into genetically related packages. The sequence stratigraphic study utilized approximately 5000 km of seismic data with a line density of approximately 10 × 20 km. Available well control was integrated into the study by means of synthetic seismograms. Limited palaeontological control utilizing largely dinocysts and radiolaria allowed the identification of 11 Paleocene/Eocene bioevents. The section was subdivided into nine Paleocene and six Eocene sequences, each separated by Type 1 unconformities. Four of the Paleocene and one of the Eocene packages had evidence of multiple Type 1 unconformities and these are described as sequence sets. Sequence development has been related to the tectonic subsidence history of the basin. Early in Paleocene times, rapid subsidence resulted in the deposition of thick sequences with distinct shelf, slope and basinal systems. Nine sequences were deposited with a combined maximum thickness of 12000 ft (3660 m). The following period, late Paleocene to early Eocene, was marked by slower subsidence; thin sequences and ramp systems with seven sequences were deposited with a maximum thickness of 2400 ft (730 m). More rapid subsidence during the late Eocene resulted in five sequences with distinct shelf, slope and basinal systems with a thickness of up to 3500 ft (1070 m). The periods of slower subsidence in the Faeroe Basin may have occurred in response to active rifting in other adjacent basins along the Atlantic margin. The distinct basinal systems which developed during times of more rapid subsidence were more likely to develop sand-prone basin floor deposits.