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TitleRift zones underlying the continental margin offshore central Labrador, Canada
AuthorKeen, C E; Dickie, K; Dafoe, LORCID logo
Source5th Atlantic Conjugate Margins Conference; 2017.
Alt SeriesNatural Resources Canada, Contribution Series 20170180
Meeting5th Atlantic Conjugate Margins Conference; Porto de Galinhas, Pernambuco; BR; August 23-25, 2017
File formatpdf
ProvinceEastern offshore region
AreaLabrador Margin
Subjectsstructural geology; general geology; seismic reflection surveys; basement geology; tectonic evolution; basin evolution; structural basins; structural interpretations
ProgramGEM2: Geo-mapping for Energy and Minerals Baffin Petroleum Systems
Released2017 01 01
AbstractNew 2D seismic reflection data across the Labrador margin provides us with an improved image of its deep basement structure and further insight into the evolution of non-volcanic margins globally. Over the last several decades a number of studies have investigated the nature of the continent-ocean transition zone on this margin, as well as on its conjugate, off West Greenland. We describe some of the new seismic data and related potential field data, in relation to earlier studies which include a deep velocity profile.
The seismic data crosses three major structural and compositional zones defined by earlier studies as: 1) extended continental crust, including a hyper-extended region, partly underlain by serpentinised mantle; 2) exhumed and serpentinised continental mantle; and 3) oceanic crust. In this study, we extend these zones laterally to over 200 km along the margin.
The continental crust is hyper-extended over tens of kilometres landward of the breakup location, where normal faults and possible low angle detachment surfaces are present. Some of these are near or at the base of the crust. Further seaward, a zone of serpentinised mantle underlies the sediments and the seismic character of these rocks is very different from that of continental crust.
Within the oceanic zone we define a further sub-division into a 'proto- oceanic' domain with thin, variable oceanic crust and ages of about 70-65 Ma (magnetic chrons 27 to 31) and a steady-state sea floor spreading region further seaward.
We compare these results to earlier studies of the West Greenland conjugate margin and to other well-studied magma-poor margins and find they are remarkably similar to those off Iberia and Newfoundland.
Summary(Plain Language Summary, not published)
Offshore of Labrador, new industry seismic reflection data provides enhanced images of the deep basement structure where the rocks of the continental margin thin and transition into oceanic crust underlying the central part of the Labrador Sea. This transition is important to understand in regional basin studies as it provides tectonic context and age constraints for the overlying sediments and their petroleum potential. Three previous major structural zones are described and extrapolated laterally along the margin for over 200 km. We show the seismic and potential field characteristics of these zones and further define a 'proto-oceanic' domain of early, thin oceanic crust. The results are compared to the conjugate West Greenland margin and other regions with notable similarities to those off Iberia and Newfoundland.

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