AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin

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The Olga Basin (northern Barents Sea) – a Caledonian or Timanian affinity?

Abstract

The epicontinental Barents Sea experienced multiple stress regime changes including Paleozoic continental collision, multi-stage late Paleozoic to Mesozoic rifting and late Cenozoic uplift and erosion. While the SW Norwegian Barents Sea is well covered by academic as well as industry-driven studies the tectonic evolution of the NE Norwegian Barents Sea is only known from sparse seismic data and geological data from the Svalbard and Franz Josef Land archipelagos. Magnetic data reveal a NNW-SSE trend in the NW Barents Sea which appears to line up with N-S striking structures on Svalbard. A second NE-SW striking Caledonian arm is assumed to run through this region crosscutting almost perpendicular important structural elements such as the Olga Basin. We acquired geophysical and geological data in the wider area of the Olga Basin southeast of Svalbard in 2015 in order to reconstruct the basin evolution with regard to inherited structures. The obtained data include ~1750 km of 2D multi-channel seismic lines, ~350 km of wide angle seismic lines by means of sonobuoys, sediment echosounder data, multi-beam data and potential field data. Interpretation of the seismic profiles reveal a post-Caledonian Olga Basin which developed as W-E striking halfgraben bounded by a W-E trending normal fault in the north. By additional analysis and interpretation of potential field data and vintage seismic lines (BGR74, BGR76) we suggest a Paleozoic basin system. Interestingly, the basin system is characterized by unusual positive magnetic and gravitational anomalies. The correlation of the earliest subsidence phase and magnetic and gravity anomalies with the preservation of Cretaceous sediments indicates that deeper inherited structures again influenced the Cenozoic basin inversion. The basin axis neither fits the assumed Caledonian trends nor to the striking of Carboniferous rifting for that region. We speculate whether this Paleozoic basin system developed entirely independent from proposed Caledonian structures or whether this region has even a Timanian affinity.