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| Titel |
Full-fit reconstruction of the Labrador Sea and Baffin Bay |
| VerfasserIn |
M. Hosseinpour, R. D. Müller, S. E. Williams, J. M. Whittaker |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 4, no. 2 ; Nr. 4, no. 2 (2013-11-26), S.461-479 |
| Datensatznummer |
250084945
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| Publikation (Nr.) |
 copernicus.org/se-4-461-2013.pdf |
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| Zusammenfassung |
| Reconstructing the opening of the Labrador Sea and Baffin Bay between
Greenland and North America remains controversial. Recent seismic data
suggest that magnetic lineations along the margins of the Labrador Sea,
originally interpreted as seafloor spreading anomalies, may lie within the
crust of the continent–ocean transition. These data also suggest a more
seaward extent of continental crust within the Greenland margin near
Davis Strait than assumed in previous full-fit reconstructions. Our study
focuses on reconstructing the full-fit configuration of Greenland and North
America using an approach that considers continental deformation in a
quantitative manner. We use gravity inversion to map crustal thickness across
the conjugate margins, and assimilate observations from available seismic
profiles and potential field data to constrain the likely extent of different
crustal types. We derive end-member continental margin restorations following
alternative interpretations of published seismic profiles. The boundaries
between continental and oceanic crust (COB) are restored to their
pre-stretching locations along small circle motion paths across the region of
Cretaceous extension. Restored COBs are fitted quantitatively to compute
alternative total-fit reconstructions. A preferred full-fit model is chosen
based on the strongest compatibility with geological and geophysical data.
Our preferred model suggests that (i) the COB lies oceanward of magnetic
lineations interpreted as magnetic anomaly 31 (70 Ma) in the Labrador Sea,
(ii) all previously identified magnetic lineations landward of anomaly 27
reflect intrusions into continental crust and (iii) the Ungava fault zone in
Davis Strait acted as a leaky transform fault during rifting. This robust
plate reconstruction reduces gaps and overlaps in Davis Strait and
suggests that there is no need for alternative models proposed for
reconstructions of this area including additional plate boundaries in North
America or Greenland. Our favoured model implies that break-up and formation
of continent–ocean transition (COT) first started in the southern Labrador
Sea and Davis Strait around 88 Ma and then propagated north and southwards
up to the onset of real seafloor spreading at 63 Ma in the Labrador Sea. In
Baffin Bay, continental stretching lasted longer and actual break-up and
seafloor spreading started around 61 Ma (chron 26). |
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