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Continental breakup and the onset of ultraslow seafloor spreading off Flemish Cap on the Newfoundland rifted margin.
- Source :
-
Geology . Jan2004, Vol. 32 Issue 1, p93-96. 4p. 2 Graphs. - Publication Year :
- 2004
-
Abstract
- Prestack depth-migrated seismic reflection data collected off Flemish Cap on the Newfoundland margin show a structure of abruptly thinning continental crust that leads into an oceanic accretion system. Within continental crust, there is no clear evidence for detachment surfaces analogous to the S reflection off the conjugate Galicia Bank margin, demonstrating a first-order asymmetry in final rift development. Anomalously thin (3-4 km), magmatically produced oceanic crust abuts very thin continental crust and is highly tectonized. This indicates that initial accretion of the oceanic crust was in a magma-limited setting similar to presentday ultraslow spreading environments. Seaward, oceanic crust thins to <1.3 km and exhibits an unusual, highly reflective layering. We propose that a period of magma starvation led to exhumation of mantle in an oceanic core complex that was subsequently buried by deep-marine sheet flows to form this layering. Subsequent seafloor spreading formed normal, ∼6-km-thick oceanic crust. This interpretation implies large fluctuations in the available melt supply during the early stages of seafloor spreading before a more typical slow-spreading system was established. Keywords: continental margin; seafloor spreading; extension tectonics; continental breakup. [ABSTRACT FROM AUTHOR]
- Subjects :
- *SEISMIC reflection method
*OCEAN
*GEOLOGY
*EARTH sciences
Subjects
Details
- Language :
- English
- ISSN :
- 00917613
- Volume :
- 32
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Geology
- Publication Type :
- Academic Journal
- Accession number :
- 12385596
- Full Text :
- https://doi.org/10.1130/G19694.1