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Crustal structure of the French Guiana margin, West Equatorial Atlantic

Greenroyd, C.; Peirce, C.; Rodger, M.; Watts, A.B.; Hobbs, R.W.

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C. Greenroyd

M. Rodger

A.B. Watts

R.W. Hobbs


Geophysical data from the Amazon Cone Experiment are used to determine the structure and evolution of the French Guiana and Northeast Brazil continental margin, and to better understand the origin and development of along-margin segmentation. A 427-km-long combined multichannel reflection and wide-angle refraction seismic profile acquired across the southern French Guiana margin is interpreted, where plate reconstructions suggest a rift-type setting. The resulting model shows a crustal structure in which 35–37-km-thick pre-rift continental crust is thinned by a factor of 6.4 over a distance of ∼70 km associated with continental break-up and the initiation and establishment of seafloor spreading. The ocean–continent boundary is a transition zone up to 45 km in width, in which the two-layered oceanic-type crustal structure develops. Although relatively thin at 3.5–5.0 km, such thin oceanic crust appears characteristic of the margin as a whole. There is no evidence of rift-related magmatism, either as seaward-dipping sequences in the reflection data or as a high velocity region in the lower crust in the P-wave velocity model, and as a such the margin is identified as non-volcanic in type. However, there is also no evidence of the rotated fault block and graben structures characteristic of rifted margins. Consequently, the thin oceanic crust, the rapidity of continental crustal thinning and the absence of characteristic rift-related structures leads to the conclusion that the southern French Guiana margin has instead developed in an oblique rift setting, in which transform motion also played a significant role in the evolution of the resulting crustal structure and along-margin segmentation in structural style.


Greenroyd, C., Peirce, C., Rodger, M., Watts, A., & Hobbs, R. (2007). Crustal structure of the French Guiana margin, West Equatorial Atlantic. Geophysical Journal International, 169(3), 964-987.

Journal Article Type Article
Publication Date 2007-06
Deposit Date Aug 1, 2008
Publicly Available Date Jul 30, 2010
Journal Geophysical Journal International
Print ISSN 0956-540X
Electronic ISSN 1365-246X
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 169
Issue 3
Pages 964-987
Keywords Continental margins, Crustal structure, Oceanic crust, Seismic structure.


Published Journal Article (2.9 Mb)

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