Temporal and spatial cyclicity of accretion at slow-spreading ridges - evidence from the Reykjanes Ridge

Peirce, C.; Gardiner, A.; Sinha, M.C.

Abstract

A unifying model of oceanic crustal development at slow spreading rates is presented in which accretion follows a cyclic pattern of magmatic construction and tectonic destruction, controlled by along-axis variation in melt supply and coupled to along-axis variation in spreading rate and across-axis asymmetry in spreading. This study focuses on the Reykjanes Ridge, Mid-Atlantic Ridge south of Iceland, which is divided along its entire length into numerous axial volcanic ridges (AVR). Five adjacent AVRs have been analysed, located between 57°30'N and 58°30'N and south of any strong Iceland hotspot influence. The seabed morphology of each AVR is investigated using sidescan sonar data to determine relative age and eruptive history. Along-axis gravity profiles for each AVR are modelled relative to a seismically derived crustal reference model, to reveal the underlying crustal thickness and density structure. Correlating these models with seabed features, crustal structure, ridge segment morphology and relative ages, a model of cyclic ridge segmentation is developed in which accretion results in adjacent AVRs with a range of crustal features which, when viewed collectively, reveal that second-order segments on the Reykjanes Ridge have an along-axis length of 70 km and comprise several adjacent AVRs which, in turn, reflect the pattern of third-order segmentation. Tectono-magmatic accretion is shown to operate on the scale of individual AVRs, as well as on the scale of the second-order segment as a whole.

Citation

Peirce, C., Gardiner, A., & Sinha, M. (2005). Temporal and spatial cyclicity of accretion at slow-spreading ridges - evidence from the Reykjanes Ridge. Geophysical Journal International, 163(1), 56-78. https://doi.org/10.1111/j.1365-246x.2005.02738.x

• Journal Article Type: Article
• Publication Date: 2005-10
• Deposit Date: Jul 9, 2007
• Publicly Available Date: Jul 30, 2010
• Journal: Geophysical Journal International
• Print ISSN: 0956-540X
• Electronic ISSN: 1365-246X
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 163
• Issue: 1
• Pages: 56-78
• DOI: https://doi.org/10.1111/j.1365-246x.2005.02738.x
• Keywords: Crustal accretion, Crustal structure, Gravity anomalies, Mid-ocean ridges, Oceanic crust, Residual mantle Bouguer anomaly.
• Public URL: https://durham-repository.worktribe.com/output/1596638