A New Scheme for the Opening of the North Atlantic and Eurasian Basin

Andrew Zayonchek

Cenozoic plate tectonic evolution of the North Atlantic and Arctic basin and its connection with deformation of Eurasia have been studied by numerous authors based on marine/airborne magnetic and bathymetric data from the Arctic and North Atlantic oceans (e.g. Karasik, 1968; Pitman & Talwani 1972; Talwani & Eldholm 1977; Srivastava & Tapscott 1986; Lawver et al. 1990; Gaina et al. 2002, 2009; Brozena et al. 2003; Glebovsky et al. 2006; Engen et al. 2008). According to these studies the seafloor spreading in the Eurasia Basin and the Norwegian-Greenland Sea was established by the earliest Eocene. Greenland was a separate Plate until magnetic anomaly 13 (33 Ma) when it become a permanent part of North American Plate. The tectonic interpretation was based on the identification of magnetic anomalies and calculations of the poles of rotations. A comparison of all existing Eurasia–North America Plate finite rotation poles for the anomalies from 6 to 24 shows the difference in their geographical positions. For that reason, we re-identified the magnetic anomalies for the Eurasia Basin (the Gakkel Ridge) and the Norwegian-Greenland Sea (the Mohns Ridge). We picked up young and old lineation for the chrons number 6, 7, 13, 18, 20, 21, 22, 23 and 24 that are well suited for constructing a detailed plate motion model. The bend in the Gakkel Ridge could easily be seen in the sequence of magnetic lineations. This allowed us to conduct a careful merging of the same magnetic chrons situated from the different sides of the ridge. In our study the finite rotations poles for the chrons 13-24 are located very close to the 134 meridian and migrated to the North. According to the reconstruction for chron 24 the segment of the Lomonosov Ridge located next to the Franz Josef Land was still a part of the Eurasian continental margin. However, in both sides away from this location the Lomonosov Ridge was already separated from that margin by the incipient formation of normal spreading crust. We agree with Brozena et al. (2003) suggesting the existence of chron 25 which implies that the spreading here started earlier than in the Norwegian-Greenland Sea (Mohns Ridge), i.e. at around 60 – 58 Ma. Reconstruction of the Eurasia plate for chron 13 using the pole of rotation defined for the Eurasia Basin shows some misfit which implies that Greenland became a part of the North American Plate later than 33 Ma.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013