A deep seismic investigation of the Flemish Cap margin: implications for the origin of deep reflectivity and evidence for asymmetric break-up between Newfoundland and Iberia
Hopper, John R.
Tucholke, Brian E.
Louden, Keith E.
Holbrook, W. Steven
Larsen, Hans Christian
MetadataShow full item record
Seismic reflection and refraction data were acquired along the southeast margin of Flemish Cap at a position conjugate to drilling and geophysical surveys across the Galicia Bank margin. The data document first-order asymmetry during final break-up between Newfoundland and Iberia. An abrupt necking profile of continental crust observed off Flemish Cap contrasts strongly with gradual tapering on the conjugate margin. There is no evidence beneath Flemish Cap for a final phase of continental extension that resulted in thin continental crust underlain by a strong 'S'-like reflection, which indicates that this mode of extension occurred only on the Galicia Bank margin. Compelling evidence for a broad zone of exhumed mantle or for peridotite ridges is also lacking along the Flemish Cap margin. Instead, anomalously thin, 3–4-km-thick oceanic crust is observed. This crust is highly tectonized and broken up by high-angle normal faulting. The thin crust and rift structures that resemble the abandoned spreading centre in the Labrador sea suggest that initial seafloor spreading was affected by processes observed in present-day ultra-slow spreading environments. Landwards, Flemish Cap is underlain by a highly reflective lower crust. The reflectivity most likely originates from older Palaeozoic orogenic structures that are unrelated to extension and break-up tectonics.
Author Posting. © Blacwell, 2006. This article is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 164 (2006): 501–515, doi:10.1111/j.1365-246X.2006.02800.x.
Suggested CitationGeophysical Journal International 164 (2006): 501–515
Showing items related by title, author, creator and subject.
Continental interior and edge breakup at convergent margins induced by subduction direction reversal: a numerical modeling study applied to the South China Sea margin Li, Fucheng; Sun, Zhen; Yang, Hongfeng; Lin, Jian; Stock, Joann M.; Zhao, Zhongxiang; Xu, Hehua; Sun, Longtao (American Geophysical Union, 2020-10-06)The dynamics of continental breakup at convergent margins has been described as the results of backarc opening caused by slab rollback or drag force induced by subduction direction reversal. Although the rollback hypothesis ...
Greene, John A.; Tominaga, Masako; Miller, Nathaniel C. (American Geophysical Union, 2020-11-16)We model the magnetic signature of rift‐related volcanism to understand the distribution and volume of magmatic activity that occurred during the breakup of Pangaea and early Atlantic opening at the Eastern North American ...
Characterization of sills associated with the U reflection on the Newfoundland margin : evidence for widespread early post-rift magmatism on a magma-poor rifted margin Peron-Pinvidic, Gwenn; Shillington, Donna J.; Tucholke, Brian E. (John Wiley & Sons, 2010-05-25)Drilling during ODP Leg 210 penetrated two post-rift sills (dated as ∼105.3 and ∼97.8 Ma) in the deep sediments overlying basement of the continent–ocean transition zone on the magma-poor Newfoundland margin. The sill ...