Full-fit reconstruction of the Labrador Sea and Baffin Bay

• Published in: Solid Earth
• Main Authors: Hosseinpour, M, Muller, RD, Williams, SE, Whittaker, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: COPERNICUS GESELLSCHAFT MBH 2013
• Subjects: Earth Sciences; Geology; Tectonics; Baffin Bay; Greenland; Baffin; Davis Strait; Labrador Sea
• Online Access: https://doi.org/10.5194/se-4-461-2013; http://ecite.utas.edu.au/88445

Reconstructing the opening of the Labrador Seaand Baffin Bay between Greenland and North America remainscontroversial. Recent seismic data suggest that magneticlineations along the margins of the Labrador Sea, originallyinterpreted as seafloor spreading anomalies, may liewithin the crust of the continentocean transition. Thesedata also suggest a more seaward extent of continental crustwithin the Greenland margin near Davis Strait than assumedin previous full-fit reconstructions. Our study focuses on reconstructingthe full-fit configuration of Greenland and NorthAmerica using an approach that considers continental deformationin a quantitative manner. We use gravity inversionto map crustal thickness across the conjugate margins, andassimilate observations from available seismic profiles andpotential field data to constrain the likely extent of differentcrustal types. We derive end-member continental marginrestorations following alternative interpretations of publishedseismic profiles. The boundaries between continentaland oceanic crust (COB) are restored to their pre-stretchinglocations along small circle motion paths across the regionof Cretaceous extension. Restored COBs are fitted quantitativelyto compute alternative total-fit reconstructions. A preferredfull-fit model is chosen based on the strongest compatibilitywith geological and geophysical data. Our preferredmodel suggests that (i) the COB lies oceanward of magneticlineations interpreted as magnetic anomaly 31 (70 Ma)in the Labrador Sea, (ii) all previously identified magneticlineations landward of anomaly 27 reflect intrusions intocontinental crust and (iii) the Ungava fault zone in DavisStrait acted as a leaky transform fault during rifting. This robustplate reconstruction reduces gaps and overlaps in DavisStrait and suggests that there is no need for alternative modelsproposed for reconstructions of this area including additionalplate boundaries in North America or Greenland.Our favoured model implies that break-up and formation ofcontinentocean transition (COT) first started in the southernLabrador Sea and Davis Strait around 88Ma and thenpropagated north and southwards up to the onset of realseafloor spreading at 63 Ma in the Labrador Sea. In BaffinBay, continental stretching lasted longer and actual break-upand seafloor spreading started around 61 Ma (chron 26).