Mafic intrusions east of Svalbard imaged by active-source seismic tomography

• Published in: Tectonophysics
• Main Authors: Minakov, Alexander, Mjelde, Rolf, Faleide, Jan Inge, Flueh, Ernst R., Dannowski, Anke, Keers, Henk
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2012
• Subjects: Amerasia Basin; Arctic; Barents Sea; Svalbard
• Online Access: https://oceanrep.geomar.de/id/eprint/13317/; https://oceanrep.geomar.de/id/eprint/13317/2/minakovetal-2012.pdf; https://doi.org/10.1016/j.tecto.2011.11.015

A seismic refraction and reflection tomography experiment was performed across the igneous province east of Svalbard which is a part of the Cretaceous High Arctic Large Igneous Province. Seismic travel times from 12 ocean bottom seismometers/hydrophones deployed along a 170 km line are inverted to produce smooth 2D images of the crustal P-wave velocity and geometry of the acoustic basement and Moho. The inversion of travel times was complemented by forward elastic wave propagation modeling. Integration with onshore geology as well as multichannel seismic, magnetic and gravity data have provide additional constraints used in the geological interpretation. The seismic P-wave velocity increases rapidly with depth, starting with 3 km/s at the sea floor and reaching 5.5 km/s at the bottom of the upper sedimentary layer. The thickness of this layer increases eastward from 2 km to 3.5 km. On average the P-wave velocity in the crystalline crust increases with depth from 5.5 km/s to 6.8 km/s. The crustal thickness is typical for continental shelf regions (30–34 km). Finger-shaped high-velocity anomalies, one reaching 12% and two of 4–6% velocity perturbation, are obtained. These velocity anomalies are concomitant with Lower Cretaceous basaltic lava flows and sills in the shallow sediments and elongated gravity and magnetic highs, traced towards the northern Barents Sea passive continental margin. We interpret the obtained velocity anomalies as signatures of dikes emplaced in the basement during breakup and subsequent spreading in the Arctic Amerasia Basin.