Publication Date:
2022-05-25
Description:
Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): B09402, doi:10.1029/2005JB003981.
Description:
Prestack depth migrations of seismic reflection data collected around the Ocean
Drilling Program (ODP) Leg 210 transect on the Newfoundland nonvolcanic margin
delineate three domains: (1) extended continental crust, (2) transitional basement, and (3) apparent slow spreading oceanic basement beyond anomaly M3 and indicate first-order differences between this margin and its well-studied conjugate, the Iberia margin. Extended continental crust thins abruptly with few observed faults, in stark contrast with the system of seaward dipping normal faults and detachments imaged within
continental crust off Iberia. Transition zone basement typically appears featureless in
seismic reflection profiles, but where its character can be discerned, it does not resemble most images of exhumed peridotite off Iberia. Seismic observations allow three explanations for transitional basement: (1) slow spreading oceanic basement produced by unstable early seafloor spreading, (2) exhumed, serpentinized mantle with different properties from that off Iberia, and (3) thinned continental crust, likely emplaced by one or more detachment or rolling-hinge faults. Although we cannot definitively discriminate between these possibilities, seismic reflection profiles together with coincident wide-angle seismic refraction data tentatively suggest that the majority of transitional basement is thinned
continental crust emplaced during the late stages of rifting. Finally, seismic profiles image abundant faults and significant basement topography in apparent oceanic basement. These observations, together with magnetic anomaly interpretations and the recovery of mantle peridotites at ODP Site 1277, appear to be best explained by the interplay of extension and
magmatism during the transition from nonvolcanic rifting to a slow spreading oceanic accretion system.
Description:
The SCREECH program was funded by
U.S. National Science Foundation grant OCE-9819053 to Woods Hole Oceanographic Institution, by the Danish Research Foundation (Danmarks Grundforskningsfond), and by the Natural Science and Engineering Council of Canada. D. Shillington was also supported by NSF grant OCE-0241940
and by the University of Wyoming Graduate School. B. Tucholke acknowledges
additional support from NSF grant OCE-0326714 and the Henry Bryant Bigelow Chair in Oceanography at Woods Hole Oceanographic
Institution.
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
11295345 bytes
Format:
application/pdf
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