Crustal structure of the ocean-continent transition at Flemish Cap : seismic refraction results

View/ Open
Date
2003-11-19Author
Funck, Thomas
Concept link
Hopper, John R.
Concept link
Larsen, Hans Christian
Concept link
Louden, Keith E.
Concept link
Tucholke, Brian E.
Concept link
Holbrook, W. Steven
Concept link
Metadata
Show full item recordCitable URI
https://hdl.handle.net/1912/3555As published
https://doi.org/10.1029/2003JB002434DOI
10.1029/2003JB002434Abstract
We conducted a seismic refraction experiment across Flemish Cap and into the deep basin east of Newfoundland, Canada, and developed a velocity model for the crust and mantle from forward and inverse modeling of data from 25 ocean bottom seismometers and dense air gun shots. The continental crust at Flemish Cap is 30 km thick and is divided into three layers with P wave velocities of 6.0–6.7 km/s. Across the southeast Flemish Cap margin, the continental crust thins over a 90-km-wide zone to only 1.2 km. The ocean-continent boundary is near the base of Flemish Cap and is marked by a fault between thinned continental crust and 3-km-thick crust with velocities of 4.7–7.0 km/s interpreted as crust from magma-starved oceanic accretion. This thin crust continues seaward for 55 km and thins locally to ~1.5 km. Below a sediment cover (1.9–3.1 km/s), oceanic layer 2 (4.7–4.9 km/s) is ~1.5 km thick, while layer 3 (6.9 km/s) seems to disappear in the thinnest segment of the oceanic crust. At the seawardmost end of the line the crust thickens to ~6 km. Mantle with velocities of 7.6–8.0 km/s underlies both the thin continental and thin oceanic crust in an 80-km-wide zone. A gradual downward increase to normal mantle velocities is interpreted to reflect decreasing degree of serpentinization with depth. Normal mantle velocities of 8.0 km/s are observed ~6 km below basement. There are major differences compared to the conjugate Galicia Bank margin, which has a wide zone of extended continental crust, more faulting, and prominent detachment faults. Crust formed by seafloor spreading appears symmetric, however, with 30-km-wide zones of oceanic crust accreted on both margins beginning about 4.5 m.y. before formation of magnetic anomaly M0 (~118 Ma).
Description
Author Posting. © American Geophysical Union, 2003. 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 108, B11 (2003): 2531, doi:10.1029/2003JB002434.
Collections
Suggested Citation
Journal of Geophysical Research 108, B11 (2003): 2531Related items
Showing items related by title, author, creator and subject.
-
Lower crustal variability and the crust/mantle transition at the Atlantis Massif oceanic core complex
Blackman, Donna K.; Collins, John A. (American Geophysical Union, 2010-12-18)Seismic refraction data provide new constraints on the structure of the lower oceanic crust and its variability across the Atlantis Massif oceanic core complex, ∼30°N on the Mid-Atlantic Ridge. A 40 km-long spreading-parallel ... -
Data adaptive velocity/depth spectra estimation in seismic wide angle reflection analysis
Leverette, Steven John (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1977-07)In studying the earth with reflection seismics, one of the major unknowns is the velocity structure of the medium. Techniques used to determine the velocity structure commonly involve multi-channel arrays which measure ... -
Crustal structure across the Grand Banks–Newfoundland Basin Continental Margin – I. Results from a seismic refraction profile
Lau, K. W. Helen; Louden, Keith E.; Funck, Thomas; Tucholke, Brian E.; Holbrook, W. Steven; Hopper, John R.; Larsen, Hans Christian (2006-03-03)A P-wave velocity model along a 565-km-long profile across the Grand Banks/Newfoundland basin rifted margin is presented. Continental crust ~36-kmthick beneath the Grand Banks is divided into upper (5.8-6.25 km/s), middle ...