Deformable Plate Modelling Provides a New Perspective on the Hyper-extended Basins of the Norwegian Margin
A new deformable plate model for the North Atlantic between NO and Greenland has been developed using seismic and well data provided by Idemitsu Petroleum Norge. The relative movement of Greenland to the Barents Shelf can be modelled accurately during this period of major transtension on the De Geer Megashear. Our deformable plate modelling provides evidence for very high beta factors along the NE Greenland – Barents Sea margin in the period Early Eocene to Early Miocene when large areas of the outer margin have beta values of greater than 2 just for this period. These high levels of extension were superimposed on earlier extension in the Mesozoic and Carboniferous, resulting in the hyper-extended margin we see today. Paleocene magnetic anomalies in the North Atlantic and Labrador Sea (chrons C27-C24) provide reasonable control for calculation of Euler poles of rotation defining the relative movement of Greenland and NO. Using these Euler poles to model the plate movement of Greenland relative to the Vøring-Lofoten margin in combination with maps of total crustal thinning from 2D flexural backstripping and gravity inversion modelling, we have estimated the amount of mid-late Paleocene pre-breakup extension (~57 to 54 Ma) that occurred across the margin. With the subsequent removal of the effects of this late-stage extension and the restoration of the pre-volcanic basin geometry, the 57 Ma plate tectonic reconstruction in our study provides us with a more accurate picture of the margin at that time. The mid-Paleocene reconstruction clearly shows for the first time the relative position of the Danmarkshavn Ridge on trend with the NE part of the Vøring Marginal High. The amount and direction of earlier Paleocene and Mesozoic stretching has also been calculated and the effects incrementally removed to produce a series of reconstructions to 150 Ma. The deformable model shows that the axis of stretching migrates towards the COB, from rifting to continental break-up, with large amounts of stretching at the continental margin immediately prior to breakup. In the deepest part of the Bjørnøya Basin beta factors of over 3 are produced by a Late Jurassic (150 Ma) rift event. This contrasts with beta factors of about 2 in the Hammerfest and Nordkapp basins to the east which are typical of a normal rift basin. The high beta values in the axis of the Bjørnøya Basin are therefore interpreted to be a hyper-extended basin that formed in the Late Jurassic - Early Cretaceous. The hyper-extension basins stretch from the West Orphan Basin in Newfoundland to the Bjørnøya Basin, passing through the Vøring Basin and Thetis Basin in NE Greenland. The Late Jurassic reconstruction shows the relative position of the Barents Sea and NE Greenland margins prior to the basins being hyper-extended. The Veslemøy High and Danmarkshavn Ridge are aligned in the Late Jurassic which leads us to believe that they have a shared tectonic evolution.
AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013