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Woods Hole Oceanographic Institution

Juan Pablo Canales

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Publications
»41. R2K Advances in Seismic Imaging
Oceanography, 2012

»40. R2K Seismic Studies
Oceanography, 2012

»39. Melt bodies off the EPR
Nature Geoscience, 2012

»38. JdF Plate: Gravity structure
G-cubed, 2011

»37. JdF Plate: Layer 2B structure
G-cubed, 2011

»36. Kane waveform tomography
GRL, 2010

»35. Kane Oceanic Core Complex
G-cubed, 2009

»34. Geophysical signatures of oceanic core complexes
GJI, 2009

»33. Accretion of the lower crust
Nature, 2009

»32. Faulting of the Juan de Fuca plate
EPSL, 2009

»31. Axial topography os the Galapagos Spreading Center
G-cubed, 2008

»30. Juan de Fuca Ridge flanks
G-cubed, 2008

»29. Seismic structure of oceanic core complexes
G-cubed, 2008

»28. Juan de Fuca Ridge: structure and hotspots
G-cubed, 2008

»27. Structure of the TAG segment, Mid-Atlantic Ridge
G-cubed, 2007

»26. Detachment faulting at TAG, Mid-Atlantic Ridge
Geology, 2007

»25. Structure of the Endeavour segment, Juan de Fuca Ridge
JGR, 2007

»24. Magma beneath Lucky Strike Hydrothermal Field
Nature, 2006

»23. Magma chamber of the Cleft segment, Juan de Fuca Ridge
EPSL, 2006

»22. Topography and magmatism at the Juan de Fuca Ridge
Geology, 2006

»21. Structure of the southern Juan de Fuca Ridge
JGR, 2005

»20. Sub-crustal magma lenses
Nature, 2005

»19. Constructing the crust at the Galapagos Spreading Center
JGR, 2004

»18. Atlantis core complex
EPSL, 2004

»17. Morphology of the Galapagos Spreading Center
G-cubed, 2003

»16. Crustal structure of the East Pacific Rise
GJI, 2003
»15. Plume-ridge interaction along the Galapagos Spreading Center
G-cubed, 2002

»14. Compensation of the Galapagos swell
EPSL, 2002

»13. Structure of Tenerife, Canary Islands
JVGR, 2000

»12. Underplating in the Canary Islands
JVGR, 2000

»11. Structure of the Mid-Atlantic Ridge (MARK, 23?20'N)
JGR, 2000

»10. Structure of the Mid-Atlantic Ridge (35?N)
JGR, 2000

»9. Structure of Gran Canaria, Canary Islands
J. Geodyn., 1999

»8. Structure of overlapping spreading centers in the MELT area
GRL, 1998

»7. Crustal thickness in the MELT area
Science, 1998

»6. The MELT experiment
Science, 1998

»5. The Canary Islands swell
GJI, 1998

»4. Morphology of the Galapagos Spreading Center
JGR, 1997

»3. Faulting of slow-spreading oceanic crust
Geology, 1997

»2. Flexure beneath Tenerife, Canary Islands
EPSL, 1997

»1. Elastic thickness in the Canary Islands
GRL, 1994



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Canales, J.P., R.S. Detrick, D.R. Toomey and W.D.S. Wilcock, Segment-scale variations in the crustal structure of 150-300 kyr old fast spreading oceanic crust (East Pacific Rise, 8?15'N-10?5'N) from wide-angle seismic refraction profiles, Geophys. J. Int., 152, 766-794, 2003

[PDF]

Abstract

We have simultaneously inverted seismic refraction and wide-angle Moho reflection travel times for the two-dimensional crustal thickness and velocity structure of 150- to 300-k.y.-old crust along the East Pacific Rise (EPR) between the Siqueiros and Clipperton fracture zones (FZ). Our results show a strong correlation between ridge segmentation and upper- and mid-crustal seismic velocities, with higher velocities near segment centers and lower velocities near segment ends. Low crustal velocities at the Clipperton and Siqueiros FZ are interpreted as fracturing resulting from brittle deformation of the crust in the transform domain. A relict overlap basin left on the Pacific plate by the 9?03'N overlapping spreading center (OSC) as it propagated southward is associated with a large (~1 km/s), negative upper- and mid-crustal velocity anomaly. This anomaly is consistent with the presence of an unusually thick extrusive section within the basin and with tectonic alteration, fracturing, and shearing due to rotation of the basin as it was formed. The discordant zone left by this OSC on the Cocos plate is characterized by moderately low crustal velocities, probably due to crustal fracturing as the OSC propagated into older crust. Higher crustal velocities near segment centers may reflect a higher ratio of dikes to extrusives in the upper crust, and lower intensity tectonic alteration of the crust, than near segment ends.

The mean crustal thickness along the EPR between the Siqueiros and Clipperton FZs is 6.7-6.8 km. The thickest crust is found beneath the Lamont seamounts (~9 km), and in a southward-pointing, V-shaped band located just north of the off-axis trace of the 9?03'N OSC (7.3-7.8 km). The thinnest crust (<6 km) is found proximal to the Clipperton and Siqueiros FZ. The crust associated with the off-axis trace of the 9?03'N OSC is not anomalously thin, suggesting that magma supply beneath the OSC is similar to that of the northern and southern segments. We see a similar pattern of crustal thickness variation to that determined using multichannel reflection data, including a gradual thickening of the crust from north to south along the northern ridge segment, and the location of the thickest crust just north of the 9?03?N OSC. However, the magnitude of along-axis crustal thickness variation we observe along the northern ridge segment between 9?50?N and the 9?15?N OSC (~1.3-1.8 km, excluding the Lamont seamounts) is significantly less than the 2.3 km of variation previously reported, weakening the case for the existence of a low density mantle diapir at 9?50'N inferred from gravity data. The band of thick crust located just north of the off-axis trace of the 9?03'N OSC suggests a close genetic link between this feature and the OSC. Thus we attribute the pattern of crustal thickness variations along the northern segment to the kinematics of the southward-propagating 9?03?N OSC over the past 0.5 My, and not to along-axis melt migration away from a mantle diapir as previously proposed.

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