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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 9N 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. 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 9N East Pacific Rise Journal of Geophysical Research, 108, (B10), art. 2464. (doi:10.1029/2002JB002163).

Record type: Article


We present a three-dimensional upper crustal model of the 9degrees03'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 similar to 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 ( similar to 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 similar to 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

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Published date: 2003
Keywords: overlapping spreading center, magma supply, ridge segmentation, ridge propagation, crustal evolution, oceanic crust.


Local EPrints ID: 1305
ISSN: 0148-0227
PURE UUID: 2b13e4f2-4701-4af0-87d3-d0e308464277

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Date deposited: 16 Apr 2004
Last modified: 17 Jul 2017 17:17

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

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