Temporal and spatial cyclicity of accretion at slow-spreading ridges: evidence from the Reykjanes Ridge
Peirce, C., Gardiner, A. and 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. (doi:10.1111/j.1365-246X.2005.02738.x).
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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.
|Keywords:||crustal accretion, crustal structure, gravity anomalies, mid-ocean ridges, oceanic crust, residual mantle bouguer anomaly|
|Subjects:||Q Science > QE Geology
G Geography. Anthropology. Recreation > GC Oceanography
|Divisions:||University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
|Date Deposited:||28 Sep 2005|
|Last Modified:||28 Jun 2012 09:40|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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