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Compressional deformation north of Easter microplate : a manned submersible and seafloor gravity investigation

Searle, R.C.; Francheteau, J.; Armijo, R.

Compressional deformation north of Easter microplate : a manned submersible and seafloor gravity investigation Thumbnail


Authors

R.C. Searle

J. Francheteau

R. Armijo



Abstract

We have investigated an E-W compressional ridge in 0.9 Ma lithosphere of the Nazca Plate, just north of the Easter microplate on the East Pacific Rise, using a combination of visual observation and seabed gravity measurements from four manned submersible dives. Three of the dives made a 26 km long traverse across the ridge during which 14 gravity measurements were made. The observations confirm the presence of active thrust faulting on the 1.1 km high south face of the ridge. However, the gravity precludes the existence of a simple low angle thrust, and is only compatible with significant crustal shortening and thickening if the block to the south of the thrust has a lower density than the overriding block. Visual and sonar observations of pervasive fine-scale tectonism in this area lend some support to this idea. Alternatively there could be oblique thrusting on a high-angle fault with relatively little crustal shortening. In addition, a small degree of crustal shortening may take place in the form of buckling of an elastic or plastic lithosphere, though this cannot explain the strong asymmetry of the ridge, which we believe must imply faulting.

Citation

Searle, R., Francheteau, J., & Armijo, R. (2006). Compressional deformation north of Easter microplate : a manned submersible and seafloor gravity investigation. Geophysical Journal International, 164(2), 359-369. https://doi.org/10.1111/j.1365-246x.2005.02812.x

Journal Article Type Article
Publication Date 2006-02
Deposit Date Feb 16, 2007
Publicly Available Date Mar 28, 2024
Journal Geophysical Journal International
Print ISSN 0956-540X
Electronic ISSN 1365-246X
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 164
Issue 2
Pages 359-369
DOI https://doi.org/10.1111/j.1365-246x.2005.02812.x.
Keywords Compression, Gravity anomalies, Lithospheric deformation, Mid-ocean ridges, Oceanic lithosphere, Plate convergence.

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