Yeo, Isobel A., Devey, Colin W. , LeBas, T.B., Augustin, Nico and Steinführer, Anja (2016) Segment-scale volcanic episodicity: Evidence from the North Kolbeinsey Ridge, Atlantic. Earth and Planetary Science Letters, 439 . pp. 81-87. DOI 10.1016/j.epsl.2016.01.029.

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Abstract

The upper oceanic crust is produced by magmatism at mid-ocean ridges, a process thought to be characterized by cyclic bouts of intense magmatic activity, separated by periods when faulting accommodates most or even all of the plate motion. It is not known whether there is a distinct periodicity to such magmatic–tectonic cycles. Here we present high-resolution sidescan sonar data from the neovolcanic zone of the North Kolbeinsey Ridge, a shallow slow-spreading ridge where high glacial and steady post-glacial sedimentation rates allow relative flow ages to be determined with a resolution of around 2 kyrusing backscatter amplitude as a proxy for sediment thickness and hence age. We identify 18 lava flow fields covering 40% of the area surveyed. A group of 7 flowfields showing the highest (and similar) backscatter intensity are scattered along 75 km of axial valley surveyed, suggesting that at least this length of the segment was magmatically active within a 1.2 kyrtime window. Based on conservative age estimates for all datable flows and estimated eruption volumes, the post-glacial volcanic activity imaged is insufficient to maintain crustal thickness, implying that episode(s) of enhanced activity must have preceded the volcanism we image.

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