TY - JOUR

T1 - Stochastic velocity inversion of seismic reflection/refraction traveltime data for rift structure of the southwest Barents Sea

AU - Clark, Stephen A.

AU - Faleide, Jan Inge

AU - Hauser, Juerg

AU - Ritzmann, Oliver

AU - Mjelde, Rolf

AU - Ebbing, Jörg

AU - Thybo, Hans

AU - Flüh, Ernst

PY - 2013

Y1 - 2013

N2 - 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, from Proterozoic craton to Paleozoic to early Cenozoic rift basins; and volcanics related to Eocene continental breakup with Greenland. Our analyses indicate a complex architecture of the crystalline crust along the profile, with crystalline crustal thicknesses ranging from 43 km beneath the Varanger Peninsula to 12 km beneath 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.

AB - 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, from Proterozoic craton to Paleozoic to early Cenozoic rift basins; and volcanics related to Eocene continental breakup with Greenland. Our analyses indicate a complex architecture of the crystalline crust along the profile, with crystalline crustal thicknesses ranging from 43 km beneath the Varanger Peninsula to 12 km beneath 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.

KW - Faculty of Science

KW - Barents Sea

KW - Stretching and thinning factors

KW - Transform margin

KW - Continental rifting

KW - Crustal structure

KW - Reflection refraction velocity modeling

KW - Barents Sea

KW - Transform margin

KW - Continental rifting

KW - Crustal structure

KW - Reflection refraction velocity modeling

KW - Stretching and thinning factors

U2 - 10.1016/j.tecto.2013.02.033

DO - 10.1016/j.tecto.2013.02.033

M3 - Journal article

VL - 593

SP - 135

EP - 150

JO - Tectonophysics

JF - Tectonophysics

SN - 0040-1951

ER -