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Karen A. Leever, University of Oslo (Norway)
Roy H. Gabrielsen, University of Oslo (Norway)
Jan Inge Faleide, University of Oslo (Norway)
Ivar Grunnaleite, IRIS (Norway)
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The late Mesozoic-Cenozoic tectonic evolution of the southwestern Barents Sea is influenced by several stages of extension and transtension that probably can be correlated to the regional plate tectonic reorganization in the North Atlantic and Arctic. Prior to, during and after the early Tertiary rifting and breakup of the northern North Atlantic, the western margin of the Barents Sea was subject to tectonic inversion, apparently involving elements of shortening in NE-SW and NW-SE directions. Several mechanisms responsible for the inversion have been suggested, including secondary effects of the uplift of Iceland and local transpression associated with the geometry and configuration of the plate boundary itself.
Solving the problem of inversion taking place in a generally extensional regime requires detailed knowledge on the geometry of the fault systems, constraints on kinematics and dating of the different episodes of deformation. By detailed seismic interpretation of inversion structures along selected basement-involved fault zones that are characterized by (multiple) inversion and of different orientation, the regional kinematics of each structure is analyzed. For the latest episode of inversion, time constraints are not directly available, because the syn-tectonic sediments have effectively been removed by glacial erosion. Still, from stratigraphic information and seismic correlation in the hangingwall fault-blocks, these movements can be dated to later than the earliest Tertiary. Improved constraints on the kinematics of inversion will allow inferences on timing, to place the event in the regional (plate) tectonic framework, and to give insight in the late Mesozoic - Cenozoic dynamics of the northern North Atlantic. Information from numerical and analogue models is used in testing the various primary tectonic configurations, the relation between this configuration and the secondary structuring, and the possible effect of strain-partition.
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