Oceanography The Official Magazine of
The Oceanography Society
Volume 20 Issue 01

View Issue TOC
Volume 20, No. 1
Pages 90 - 101


Ultraslow-Spreading Ridges: Rapid Paradigm Changes

By Jonathan E. Snow  and Henrietta N. Edmonds 
Jump to
Citation Copyright & Usage
First Paragraph

Ultraslow-spreading ridges (< 20 mm yr–1 full rate) represent a major departure from the style of crustal accretion seen in the rest of the ocean basins. Since the 1960s, observations of fast- and slow-spreading mid-ocean ridges of the Pacific and Atlantic Oceans, combined with those of ophiolites (pieces of oceanic crust that have been thrust onto land through plate-tectonic processes), were used to define the conceptual structural, tectonic, and hydrothermal architecture of oceanic crust. Over the last 15 years, studies of ultraslow-spreading ridges have identified several anomalies that cannot be explained by the standard model of oceanic crustal formation. Thus, in recent years, ultraslow-spreading ridges have become recognized as a class unto themselves. Their “anomalous” characteristics in fact provide key information about many of the underlying processes that govern crustal accretion at all spreading rates. Ultraslow ridges include the Southwest Indian Ridge (between Africa and Antarctica), the Gakkel Ridge (which bisects the Arctic Ocean), and several smaller ridges (Figure 1).


Snow, J.E., and H.N. Edmonds. 2007. Ultraslow-spreading ridges: Rapid paradigm changes. Oceanography 20(1):90–101, https://doi.org/10.5670/oceanog.2007.83.

Copyright & Usage

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.