| 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 swellEPSL, 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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Nedimovic, M.R., S.M. Carbotte, J.B. diebold, A. Harding, J.P. Canales, and G.M. Kent, Upper crustal evolution across the Juan de Fuca ridge flanks, Geochem., Geophys., Geosyst. 9, Q09006 doi:10.1029/2008GC002085, 2008
Abstract
Recent P wave velocity compilations of the oceanic crust indicate that the velocity of the uppermost layer 2A doubles or reaches 4.3 km/s found in mature crust in <10 Ma after crustal formation. This velocity change is commonly attributed to precipitation of low-temperature alteration minerals within the extrusive rocks associated with ridge-flank hydrothermal circulation. Sediment blanketing, acting as a thermal insulator, has been proposed to further accelerate layer 2A evolution by enhancing mineral precipitation. We carried out 1-D traveltime modeling on common midpoint supergathers from our 2002 Juan de Fuca ridge multichannel seismic data to determine upper crustal structure at 3 km intervals along 300 km long transects crossing the Endeavor, Northern Symmetric, and Cleft ridge segments. Our results show a regional correlation between upper crustal velocity and crustal age. The measured velocity increase with crustal age is not uniform across the investigated ridge flanks. For the ridge flanks blanketed with a sealing sedimentary cover, the velocity increase is double that observ
ed on the sparsely and discontinuously sedimented flanks (60% increase versus 28%) over the same crustal age range of 5–9 Ma. Extrapolation of velocity-age gradients indicates that layer 2A velocity reaches 4.3 km/s by 8 Ma on the sediment blanketed flanks compared to 16 Ma on the flanks with thin and discontinuous sediment cover. The computed thickness gradients show that layer 2A does not thin and disappear in the Juan de Fuca region with increasing crustal age or sediment blanketing but persists as a relatively low seismic velocity layer capping the deeper oceanic crust. However, layer 2A on the fully sedimented ridgeflank sectionsis on average thinner than on the sparsely and discontinuously sedimented flanks (330 ± 80 versus 430 ± 80 m). The change in thickness occurs over a 10–20km distance coincident with the onset of sediment burial. Our results also suggest that propagator wakes can have a typical layer 2A thickness and velocity. Impact of propagator wakes is evident in the chemical signature of the fluids sampled by ODP drill holes along the east Endeavor transect, providing further indication that these crustal discontinuities may be sites of localized fluid flow and alteration.
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