Abstract
BARENTS50, a new 3-D geophysical model of the crust in the Barents
Sea Region has been developed by the University of Oslo, NORSAR and
the U.S. Geological Survey. The target region comprises northern
Norway and Finland, parts of the Kola Peninsula and the East European
lowlands. Novaya Zemlya, the Kara Sea and Franz-Josef Land terminate
the region to the east, while the Norwegian-Greenland Sea marks the
western boundary. In total, 680 1-D seismic velocity profiles were
compiled, mostly by sampling 2-D seismic velocity transects, from
seismic refraction profiles. Seismic reflection data in the western
Barents Sea were further used for density modelling and subsequent
density-to-velocity conversion. Velocities from these profiles were
binned into two sedimentary and three crystalline crustal layers.
The first step of the compilation comprised the layer-wise interpolation
of the velocities and thicknesses. Within the different geological
provinces of the study region, linear relationships between the thickness
of the sedimentary rocks and the thickness of the remaining crystalline
crust are observed. We therefore used the separately compiled (area-wide)
sediment thickness data to adjust the total crystalline crustal thickness
according to the total sedimentary thickness where no constraints
from 1-D velocity profiles existed. The BARENTS50 model is based
on an equidistant hexagonal grid with a node spacing of 50 km. The
P-wave velocity model was used for gravity modelling to obtain 3-D
density structure. A better fit to the observed gravity was achieved
using a grid search algorithm which focussed on the density contrast
of the sediment-basement interface. An improvement compared to older
geophysical models is the high resolution of 50 km. Velocity transects
through the 3-D model illustrate geological features of the European
Arctic. The possible petrology of the crystalline basement in western
and eastern Barents Sea is discussed on the basis of the observed
seismic velocity structure.
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