Linking onshore-offshore basement rock architecture and brittle faults on the submerged strandflat along the SW Barents Sea margin, using high-resolution (5 x 5 m) bathymetry data
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High-resolution bathymetry data reveal astonishingly detailed and complex morphology on the shallow offshore shelf (strandflat) along the SW Barents Sea margin, outboard Troms, northern Norway. The features are compared with, and interpreted based on, known onshore geology, including Precambrian basement structures of the West Troms Basement Complex, Caledonian thrust nappes and post-Caledonian passive-margin brittle structures. The study reveals that Precambrian basement structures commonly observed onshore, such as a generally steep gneiss foliation, steeply plunging tight to isoclinal intrafolial folds, upright macro-fold limbs, duplexes and high-strain ductile shear zones are also present on the strandflat, including possible offshore continuations of Precambrian metasupracrustal belts. The results suggest that the strandflat outboard Troms is largely composed of rocks of West Troms Basement Complex affinity. A contact with Caledonian thrust nappes is interpreted to trend NW–SE within a sound in the northern parts of the study area, where it overlaps with the Late Palaeozoic–Mesozoic Fugløya transfer zone, a possible reactivated portion of a Proterozoic–Palaeozoic basement-seated fault complex. A set of linear NNE–SSW- to ENE–WSW-trending trenches truncate the ductile fabrics and are interpreted as post-Caledonian brittle faults that formed due to multiple rifting events in the Late Palaeozoic– Mesozoic as parts of the evolution of the passive continental margin of the SW Barents Sea. Aspect analysis reveals a strong correlation between the present-day landscape and tectonic elements, which indicate a pervasive tectonic influence on the present-day coastal landscape of western Troms and the outboard strandflat. Kjetil Indrevær, Department of Geology, University of Tromsø, N–9037 Tromsø, Norway. DONG E&P Norge

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