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The influence of ridge migration on the magmatic segmentation of mid-ocean ridges

Abstract

The Earth's mid-ocean ridges display systematic changes in depth and shape, which subdivide the ridges into discrete spreading segments bounded by transform faults and smaller non-transform offsets of the axis1,2,3. These morphological changes have been attributed to spatial variations in the supply of magma from the mantle, although the origin of the variations is poorly understood1,4,5. Here we show that magmatic segmentation of ridges with fast and intermediate spreading rates is directly related to the migration velocity of the spreading axis over the mantle. For over 9,500 km of mid-ocean ridge examined, leading ridge segments in the ‘hotspot’ reference frame coincide with the shallow magmatically robust segments across 86 per cent of all transform faults and 73 per cent of all second-order discontinuities. We attribute this relationship to asymmetric mantle upwelling and melt production due to ridge migration, with focusing of melt towards ridge segments across discontinuities. The model is consistent with variations in crustal structure across discontinuities of the East Pacific Rise, and may explain variations in depth of melting and the distribution of enriched lavas.

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Acknowledgements

We thank R. Katz, M. Spiegelman, R. Buck and W.B.F. Ryan for discussions during the development of these ideas. Special thanks are due to W. Haxby for GeoMapApp, which greatly aided the data analysis. This work was supported by the US National Science Foundation, the Palisades Geophysical Institute, and the Doherty Foundation.

Author information

Correspondence to S. M. Carbotte.

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The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Figure 1

This figure shows bathymetry and axial depth profiles for the Southern East Pacific Rise and Pacific-Antarctic Rise. (PDF 738 kb)

Supplementary Figure 2

This figure shows bathymetry and axial depth profiles for the Explorer-Juan de Fuca-Gorda Ridges and South East Indian Ridge. (PDF 1339 kb)

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Further reading

Figure 1: Bathymetry map and axial depth profile along the NEPR.
Figure 2: Change in axial depth verses offset length at ridge-axis discontinuities.
Figure 3: Schematic diagram illustrating asymmetric mantle upwelling beneath a migrating MOR offset at a transform fault and OSC.
Figure 4: Axial depth and chemical parameters of zero-age lavas along the NEPR.

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