Sedimentary and crustal velocities in the Norwegian‐Greenland Sea

Abstract

Refraction and wide‐angle reflection velocities from the oceanic crust and the overlying sediments in the Norwegian‐Greenland Sea have been analyzed. There is a relatively rapid increase in velocity with depth in the uppermost sediments, whereas a low constant gradient is representative of the main sediment sequence. Two regions, the northeastern Greenland Sea and the oldest parts of the basins, have particularly high velocity gradients, 0.71 and 0.85 s−1 respectively. The high gradient in the northeastern Greenland Sea is associated with the shear‐rifted margin off Svalbard. Relatively high sea floor sediment sound velocities are typical of the Norwegian‐Greenland Sea. The crustal velocities fit the Houtz‐Ewing model which divides layer 2 into layers 2A, 2B and 2C. Average velocities in the Norwegian‐Greenland Sea are: 3.88(2A), 5.18(2B), 6.05(2C), 6.66(3), and 7.80(4) km/s. Layer 2A is age dependent and has not been observed on crust older than 36 m.y. The model is not representative of the uppermost crust near the active spreading axis where one has to introduce additional layers or assume continuous velocity changes with depth.