Stochastic velocity inversion of seismic reflection/refraction traveltime data for rift structure of the southwest Barents Sea

We present results from an active-source, onshore–offshore seismic reflection/refraction transect acquired as part of the PETROBAR project (Petroleum-related studies of the Barents Sea region). The 700 km-long profile is oriented NW–SE, coincident with previously published multichannel seismic refle...

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Bibliographic Details
Published in:Tectonophysics
Main Authors: Clark, Stephen A., Faleide, Jan Inge, Hauser, Juerg, Ritzmann, Oliver, Mjelde, Rolf, Ebbing, Jörg, Thybo, Hans, Flüh, Ernst
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2013
Subjects:
Barents Sea
Bjørnøya
Greenland
Varanger
Online Access:https://oceanrep.geomar.de/id/eprint/21224/
https://oceanrep.geomar.de/id/eprint/21224/1/Clarketal.2013.pdf
https://doi.org/10.1016/j.tecto.2013.02.033
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Summary:We present results from an active-source, onshore–offshore seismic reflection/refraction transect acquired as part of the PETROBAR project (Petroleum-related studies of the Barents Sea region). The 700 km-long profile is oriented NW–SE, coincident with previously published multichannel seismic reflection profiles. We utilize layer-based raytracing in a Markov Chain Monte Carlo (MCMC) inversion to determine a probabilistic velocity model constraining the sedimentary rocks, crystalline crust, and uppermost mantle in a complex tectonic regime. The profile images a wide range of crustal types and ages, fromProterozoic craton to Paleozoic to early Cenozoic rift basins; and volcanics related to Eocene continental breakupwith Greenland. Our analyses indicate a complex architecture of the crystalline crust along the profile,with crystalline crustal thicknesses ranging from43 kmbeneath the Varanger Peninsula to 12 kmbeneath the Bjørnøya Basin. Assuming an original, post-Caledonide crustal thickness of 35 km in the offshore area, we calculate the cumulative thinning (β) factors along the entire profile. The average β factor along the profile is 1.7 ± 0.1, suggesting 211–243 km of extension, consistent with the amount of overlap derived from published plate reconstructions. Local β factors approach 3, where Bjørnøya Basin reaches a depth of more than 13 km. Volcanics, carbonates, salt, diagenesis and metamorphism make deep sedimentary basin fill difficult to distinguish from original, pre-rift crystalline crust, and thus actual stretching may in places exceed our estimates.

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