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Influence of enhanced melt supply on upper crustal structure at a mid-ocean ridge discontinuity: A three-dimensional seismic tomographic study of 9°N East Pacific Rise

Tong, C.H.; Barton, P.J.; White, R.S.; Sinha, M.C.; Singh, S.C.; Pye, J.W.; Hobbs, R.W.; Bazin, S.; Harding, A.J.; Kent, G.M.; Orcutt, J.A.

Influence of enhanced melt supply on upper crustal structure at a mid-ocean ridge discontinuity: A three-dimensional seismic tomographic study of 9°N East Pacific Rise Thumbnail


Authors

C.H. Tong

P.J. Barton

R.S. White

M.C. Sinha

S.C. Singh

J.W. Pye

R.W. Hobbs

S. Bazin

A.J. Harding

G.M. Kent

J.A. Orcutt



Abstract

We present a three-dimensional upper crustal model of the 9°03′N overlapping spreading center (OSC) on the East Pacific Rise that assists in understanding the relationship between melt sills and upper crustal structure at a ridge discontinuity with enhanced melt supply at crustal levels. Our P wave velocity model obtained from tomographic inversion of ∼70,000 crustal first arrival travel times suggests that the geometry of extrusive emplacement are significantly different beneath the overlapping spreading limbs. Extrusive volcanic rocks above the western melt sill are inferred to be thin (∼250 m). More extensive accumulation of extrusives is inferred to the west than to the east of the western melt sill. The extrusive layer inferred above the eastern melt sill thickens from ∼350 (at the neovolcanic axis) to 550 m (to the west of the melt sill). Volcanic construction is likely to be significant in the formation of ridge crest morphology at the OSC, particularly at the tip of the eastern limb. On the basis of our interpretation of the velocity model, we propose that enhanced magma supply at crustal levels at the OSC may provide an effective mechanism for the migration of ridge discontinuities. This “dynamic magma supply model” may explain the commonly observed nonsteady migration pattern of ridge discontinuities by attributing this to the temporal fluctuations in melt availability to the overlapping spreading limbs.

Citation

Tong, C., Barton, P., White, R., Sinha, M., Singh, S., Pye, J., …Orcutt, J. (2003). Influence of enhanced melt supply on upper crustal structure at a mid-ocean ridge discontinuity: A three-dimensional seismic tomographic study of 9°N East Pacific Rise. Journal of Geophysical Research, 108(B10), 2464-2473. https://doi.org/10.1029/2002jb002163

Journal Article Type Article
Publication Date Oct 9, 2003
Deposit Date Aug 17, 2015
Publicly Available Date Mar 28, 2024
Journal Journal of Geophysical Research. Solid Earth
Print ISSN 0148-0227
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 108
Issue B10
Pages 2464-2473
DOI https://doi.org/10.1029/2002jb002163
Keywords Overlapping spreading center, Magma supply, Ridge segmentation, Ridge propagation, Crustal evolution, Oceanic crust.

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Copyright Statement
Tong, C. H., Barton, P. J., White, R. S., Sinha, M. C., Singh, S. C., Pye, J. W., Hobbs, R. W., Bazin, S., Harding, A. J., Kent, G. M. and Orcutt, J. A., (2003), Influence of enhanced melt supply on upper crustal structure at a mid-ocean ridge discontinuity: A three-dimensional seismic tomographic study of 9°N East Pacific Rise, Journal of Geophysical Research: Solid Earth (1978–2012), 108(B10), 2464-2473, 10.1029/2002JB002163 (DOI). To view the published open abstract, go to http://dx.doi.org and enter the DOI.




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