What lies beneath - p229

doi:10.1038/ngeo1448

The mid-ocean ridges mark the lines along which the Earth is turning itself inside out through the process of plate tectonics. Advances in technology are helping to reveal the intricate details of the magma systems that feed the rifting process.

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Plate tectonics: Piecing together rifts - pp235-236

Douglas R. Toomey

doi:10.1038/ngeo1435

Earth's crust is formed where tectonic plates rift apart and upwelling magma solidifies. Disparate observations from rifts beneath the oceans and on land provide insights into the dynamics of rifting and opportunities for synthesis.

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Geophysical constraints on the dynamics of spreading centres from rifting episodes on land - pp242-250

Tim J. Wright, Freysteinn Sigmundsson, Carolina Pagli, Manahloh Belachew, Ian J. Hamling, Bryndís Brandsdóttir, Derek Keir, Rikke Pedersen, Atalay Ayele, Cindy Ebinger, Páll Einarsson, Elias Lewi & Eric Calais

Most of Earth's crust is created at mid-ocean ridges that are submerged deep beneath the oceans. Analyses of geodetic and seismic data from rare sections of ridges that are exposed on land in Iceland and the Afar region in east Africa demonstrate that rifting episodes at these sites operate with remarkably similar mechanisms.

doi:10.1038/ngeo1428

Protracted timescales of lower crustal growth at the fast-spreading East Pacific Rise - pp275-278

Matthew Rioux, C. Johan Lissenberg, Noah M. McLean, Samuel A. Bowring, Christopher J. MacLeod, Eric Hellebrand & Nobumichi Shimizu

doi:10.1038/ngeo1378

Rates of crust formation at mid-ocean ridges are expected to vary with rates of plate spreading. U-Pb dating of zircon minerals from the fast-spreading East Pacific Rise reveals protracted formation of gabbroic rocks over timescales comparable with slow-spreading mid-ocean ridges, suggesting similar timescales of magmatic processes at slow- and fast-spreading ridges.

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Network of off-axis melt bodies at the East Pacific Rise - pp279-283

J. P. Canales, H. Carton, S. M. Carbotte, J. C. Mutter, M. R. Nedimović, M. Xu, O. Aghaei, M. Marjanović & K. Newman

doi:10.1038/ngeo1377

At faster-spreading mid-ocean ridges, the creation of new oceanic crust through magmatism usually occurs within a narrow zone on the ridge axis. Three-dimensional seismic images of the fast-spreading East Pacific Rise reveal a network of magmatic bodies 4–8 km away from the ridge axis that seem to be connected to the axial magma chamber.

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Shallow axial magma chamber at the slow-spreading Erta Ale Ridge - pp284-288

Carolina Pagli, Tim J. Wright, Cynthia J. Ebinger, Sang-Ho Yun, Johnson R. Cann, Talfan Barnie & Atalay Ayele

doi:10.1038/ngeo1414

Thermal models predict that spreading velocity at mid-ocean rifts should influence the geometry of the underlying magma chamber. InSAR data from the slow-spreading Ethiopian Rift identify a shallow, elongated magma chamber — a feature usually associated with fast-spreading rifts — beneath the Erta Ale segment, implying that spreading velocity may not be so important after all.

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Initiation of the western branch of the East African Rift coeval with the eastern branch - p289-294

E. M. Roberts, N. J. Stevens, P. M. O'Connor, P. H. G. M. Dirks, M. D. Gottfried, W. C. Clyde, R. A. Armstrong, A. I. S. Kemp & S. Hemming

doi:10.1038/ngeo1432

Rifting of the eastern part of the East African Rift System was thought to have begun several million years before its western counterpart. Reconstructions of drainage development, combined with dating of rift-related volcanic activity, suggest that rifting in the western branch may instead have begun at the same time as in the eastern branch.

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