Tab. 1. Listing of BGR seismic refraction results off West Spitsbergen

Three main depositional sequences have been determined in the seismic records taken off West Spitsbergen(1) a Plio-Pleistocene sequence SPI-I with velocities of 1.7 to 2.8 km/sec;(2) a Pliocene allochthonous sequence SPI-II with velocities of 2.4 to 2.8 km/sec underlying unconformity U1;(3) a pre-Middle Oligocene sequence SPI-III with velocities of 2.9 to 4.8 km/sec underlying a distinct unconformity (U2) and deposited in front of the downfaulted Spitsbergen Platform indicating some opening of the Greenland Sea already before tbe time of magnetic anomaly 13 (36 m.y.b.p.).A marked change in the seismic configuration of the oceanic basement has been observed about 30 to 40 km east of the central Knipovich graben.

The transition from the oceanic crust of the Knipovich Ridge to the strongly faulted, continental substratum of the Spitsbergen Platform occurs over a narrow zone and is associated with a pre-Middle Oligocene depocenter.