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Sensitivity of seafloor bathymetry to climate-driven fluctuations in mid-ocean ridge magma supply

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Science  16 Oct 2015:
Vol. 350, Issue 6258, pp. 310-313
DOI: 10.1126/science.aad0715

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Understanding abyssal hill spacing

The most prominent topographic features on Earth are abyssal hills found on the bottom of the ocean floor. Olive et al. wanted to understand the spacing and size of these hills. They used a model that combines magma supply and the mechanical response of the crust. The model explains observations of hill spacing around mid-ocean ridges. Crustal topography appears to be a poor recorder of changes in magma supply. However, magma supply changes may be faithfully recorded at the base of the crust.

Science, this issue p. 310

Abstract

Recent studies have proposed that the bathymetric fabric of the seafloor formed at mid-ocean ridges records rapid (23,000 to 100,000 years) fluctuations in ridge magma supply caused by sealevel changes that modulate melt production in the underlying mantle. Using quantitative models of faulting and magma emplacement, we demonstrate that, in fact, seafloor-shaping processes act as a low-pass filter on variations in magma supply, strongly damping fluctuations shorter than about 100,000 years. We show that the systematic decrease in dominant seafloor wavelengths with increasing spreading rate is best explained by a model of fault growth and abandonment under a steady magma input. This provides a robust framework for deciphering the footprint of mantle melting in the fabric of abyssal hills, the most common topographic feature on Earth.

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