Rift to drift Evolution of the Jan Mayen Micro-continent and Conjugate Rifted Margins: Implication of New Aeromagnetic Surveys in the Norwegian-Greenland Sea

Laurent Gernigon

We re-evaluate the structure and spreading evolution of the Norwegian-Greenland Sea and surrounding volcanic (rifted) margins based on new high-resolution aeromagnetic surveys. The new dataset combined with seismic and gravity data allowed us to understand better the structure and evolution of the Nordic conjugate margin system from the rifting to the drifting stage. We particularly focus on the new JAS-12 aeromagnetic survey acquired between the Aegir Ridge and the Jan Mayen micro-continent, which was initially part of the Møre-Vøring-Greenland rift system. Combined with the previous NB-07 and JAS-05 surveys, our final compilation fully covers the continent-ocean transition and the whole oceanic spreading system from the Møre margin to the Jan Mayen micro-continent with high quality, high resolution and reliable magnetic data. The new dataset allowed us to get a new, consistent and precise interpretation of the magnetic polarity chrons and oceanic fractures, providing us now with the basis for more accurate rotation poles estimation, and a better basin and petroleum system reconstructions between NO, Greenland and the Jan Mayen micro-continent. The detailed fabric of the spreading system revealed by the new data indicates that two distinct tectonic phases have reshaped the Norwegian-Greenland Sea before progressive reorganisation of seafloor spreading and abortion of the Aegir Ridge in the Late Oligocene. After the continental breakup, which was dominated by severe magmatism, two major phases of spreading influenced the NO Basin. Phase I (from C24 to C21r, ~52 to 49 Ma) marks the earliest phase of spreading, probably initiated in the central and outer part of the Møre Basin. During this period, competing oceanic segments led to the formation of overlapping systems and pseudo-fault development suggesting the presence of additional micro-plates in the Norwegian-Greenland Sea. We observed also a significant change in the oceanic spreading system in the late Early Eocene and, based on observations from the surrounding areas, we suggest that this supports a major and distinct tectonic event in the Norwegian-Greenland Sea at around C21r (49-47.9 Ma). During Phase II, from C21r-C10 ? (48-28 ? Ma) of the NO Basin development, spreading rates decreased, spreading direction changed, and the number of faults with large displacements increased leading to the formation of unexpected N-S oriented oceanic fracture zones. The fan-shaped development of the spreading system initiated around C21r (~49-47.9 Ma), instead of C18-C17 (~40-38 Ma) or C24 (53.3-52.3 Ma) as previously proposed. These new observations were used to re-evaluate the tectonic evolution of the Norwegian-Greenland Sea and discuss the syn- and post-breakup basin and stratigraphic development of the surrounding continental margins and related micro-continent.

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