Acquisition, processing and interpretation of snow-streamer seismic profiles in Masi and Sennalandet, Finnmark, northern Norway
Two snow-streamer profiles were acquired by the University of Bergen in March and April 2012 within the programme ‘Mineral Resources in Northern Norway - MINN’. The two profiles are located in the Masi and Sennlandet areas in the Kautokeino and Hammerfest municipalities. The data were acquired using a combination of snow-streamer and autonomous nodes. The obtained reflectors can be traced to a depth of 4-5 km. P-wave velocities are obtained from travel-time tomography of manually picked first breaks. The velocities can be resolved down to a few hundred meters depth. We have included two interpretation examples of the Masi profile in the current acquisition and processing report. The regional c. 4-5 km wide Mierojávri-Sværholt shear zone is represented by several reflectors dipping at an angle of c. 40-50° to the southeast below the northwestern margin of the Jergul Gneiss Complex. The migrated seismic profile shows that the dip of the western and eastern segments of the Masi fault system (within the Stuoragurra fault complex) is 52° and 65°, respectively. The two postglacial fault segments seem to merge at a depth of c. 500 m. The present study proves that snow-streamer technology is an efficient way to carry out seismic profiling in snow-covered and relatively flat terrain. Using detonating cord as a seismic source has left no permanent footprint on the sparse vegetation in the Arctic, which is an advantage. We conclude that the reflection seismic data are of high quality and that the obtained reflectors can be interpreted in terms of regional geological structures continuing to a depth of 3-4 km. We suggest that the western part of the reprocessed Masi profile, and the Sennalandet profile, should be interpreted in a similar integrated way as the examples shown in the present report.