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

• 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: 2013
• Subjects: /dk/atira/pure/core/keywords/TheFacultyOfScience; Faculty of Science; Barents Sea; Stretching and thinning factors; Transform margin; Continental rifting; Crustal structure; Reflection refraction velocity modeling; Bjørnøya; Greenland; Varanger
• Online Access: https://curis.ku.dk/portal/da/publications/stochastic-velocity-inversion-of-seismic-reflectionrefraction-traveltime-data-for-rift-structure-of-the-southwest-barents-sea(e8acdb63-8e2f-45b5-b6e6-7ca2de55174d).html; https://doi.org/10.1016/j.tecto.2013.02.033

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 from 43 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. 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 ...