Crustal structure of the Barents Sea from seismic data

In 1976, the Institute of Physics of the Earth and the Institute of Oceanology, the U.S.S.R. Academy of Sciences, carried out deep seismic soundings in the Barents Sea along a profile 700 km long northeast of Murmansk. A system of reversed and overlapping traveltime curves from 200 to 400 km long has been obtained. The wave correlation was effected by several independent approaches, which identified on the records the refracted and reflected waves from boundaries in the Earth's crust and the upper mantle. Different methods were applied for the solution of the inverse problem: the isochrone method, the intercept-time method, and the iteration method.The use of these different methods gives an indication of the general applicability of the interpretation and of the most reliable elements in the seismic model.All the interpretations and representations of the section positively establish an essentially horizontal inhomogeneity of the Earth's crust in the Barents Sea. On the whole the structure is similar to that of deep sedimentary basins of the East European platform. The thickness of the sedimentary layer varies from 8 to 17 km, the average crustal thickness is about 35–40 km; the velocities in the upper part of the consolidated crust are 5.8–6.4 km/s; in the lower crust they are 6.8–7.0 km/s and higher.     

Peculiarities in the deep structure of the Sakhalin-Hokkaido-Primorye zone

The results of detailed seismic crustal investigations in the marginal part of the transition zone from the Asian continent to the Pacific Ocean are discussed. The observations were carried out during 1963 and 1964 by expeditions of the Institute of Physics of the Earth of the U.S.S.R. Academy of Sciences and the Sakhalin Complex Research Institute, Siberian Division of the U.S.S.R. Academy of Sciences. The results of these measurements have been described in detail in a monograph, by Zverev and Tulina, entitled Deep Seismic Sounding of the Earth's Crust in the Sakhalin-Hokkaido-Primorye Zone (1971).

The distribution of seismic crustal characteristics is studied and schematic maps of the surface of presumably Cretaceous and Meso-Paleozoic (or pre-Paleozoic) sediments near Sakhalin Island as well as of the mantle surface in the Sakhalin-Hokkaido-Primorye zone are presented.