Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/86884
Title: Episodic kinematics in continental rifts modulated by changes in mantle melt fraction
Authors: Moore, James Daniel Paul
Smith, Euan
Stern, Tim
Lamb, Simon
Keywords: Geodynamics
Geophysics
Issue Date: 2017
Source: Lamb, S., Moore, J. D. P., Smith, E., & Stern, T. (2017). Episodic kinematics in continental rifts modulated by changes in mantle melt fraction. Nature, 547, 84-88.
Series/Report no.: Nature
Abstract: Oceanic crust is created by the extraction of molten rock from underlying mantle at the seafloor ‘spreading centres’ found between diverging tectonic plates. Modelling studies have suggested that mantle melting can occur through decompression as the mantle flows upwards beneath spreading centres1, but direct observation of this process is difficult beneath the oceans. Continental rifts, however—which are also associated with mantle melt production—are amenable to detailed measurements of their short-term kinematics using geodetic techniques. Here we show that such data can provide evidence for an upwelling mantle flow, as well as information on the dimensions and timescale of mantle melting. For North Island, New Zealand, around ten years of campaign and continuous GPS measurements in the continental rift system known as the Taupo volcanic zone reveal that it is extending at a rate of 6–15 millimetres per year. However, a roughly 70-kilometre-long segment of the rift axis is associated with strong horizontal contraction and rapid subsidence, and is flanked by regions of extension and uplift. These features fit a simple model that involves flexure of an elastic upper crust, which is pulled downwards or pushed upwards along the rift axis by a driving force located at a depth greater than 15 kilometres. We propose that flexure is caused by melt-induced episodic changes in the vertical flow forces that are generated by upwelling mantle beneath the rift axis, triggering a transient lower-crustal flow. A drop in the melt fraction owing to melt extraction raises the mantle flow viscosity and drives subsidence, whereas melt accumulation reduces viscosity and allows uplift—processes that are also likely to occur in oceanic spreading centres.
URI: https://hdl.handle.net/10356/86884
http://hdl.handle.net/10220/44212
ISSN: 0028-0836
DOI: http://dx.doi.org/10.1038/nature22962
Rights: © 2017 Macmillan Publishers Limited, part of Springer Nature. This is the author created version of a work that has been peer reviewed and accepted for publication by Nature, Macmillan Publishers Limited, part of Springer Nature. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1038/nature22962].
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:EOS Journal Articles

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