T323 Structure and Evolution of the North Atlantic–Arctic Realm

Wednesday, 25 October 2017
8:00 AM - 12:00 PM
Yakima 1

HOW DID THE CONTINENTS BREAK APART IN THE NORWEGIAN-GREENLAND-SEA?

Paper number: T323-9
Program: Technical Sessions
Time: 10:10 AM – 10:30 AM

Authors

Abstract

The Norwegian-Greenland-Sea features a range of settings including microcontinents and conjugate volcanic margins ‘bridged’ to the south by the Greenland-Iceland-Faeroes Ridge. The latter is traditionally interpreted as a swath of thick oceanic crust left in the wake of the controversial Icelandic 'hotspot'. New aeromagnetic data combined with seismic data allow us to revisit the complex rift-to drift evolution of the Norwegian-Greenland Sea. The long period of rifting, structural style and significant amount of breakup-magmatism and seaward dipping reflectors (SDRs) clearly distinguish the conjugate volcanic (rifted) margins from magma-poor margins. We favour a tectonic scenario before the onset of breakup, where a thick sedimentary basin developed during a drastic thinning of the continental crust associated with progressive exhumation of high-grade metamorphic rocks. We interpret the crust close to the SDRs as a mixture of preserved continental crust drastically intruded by breakup-related magma. No zone of syn-rift exhumed and serpentinized continental mantle can be identified clearly near the SDR. The new aeromagnetic data suggest the onset of breakup was also a diachronic process with initial overlapping spreading centres. The volcanic margins and early spreading system developed differently and progressively along different margin segments. Inherited tectonic buffers affected early spreading ridge development leading progressively to microcontinent formation. The new magnetic data also show that an important mid-Eocene kinematic event at around chron C21r influenced the Norwegian-Greenland Sea. This event coincides with the onset of dyking and increase of rift activity (and possibly oceanic accretion?) between the so-called Jan Mayen microcontinent (or microplate complex) and the conjugate East Greenland margin. It led to ultimate lithospheric breakup of the Norwegian-Greenland Sea in the Late Oligocene. The origin(s) of microcontinent formation, in general, is/are still unclear but recent receiver function analysis indicates that the presence of an old inherited sub-crustal slab may have had a significant influence in the late reorganisation of the Norwegian-Greenland Sea.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-301150

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