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Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variations in the formation of oceanic lithosphere

Enrico Bonatti; Marco Ligi; Daniele Brunelli; Anna Cipriani; Paola Fabretti; Valentina Ferrante; Luca Gasperini; Luisa Ottolini

Title:
Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variations in the formation of oceanic lithosphere
Author(s):
Bonatti, Enrico
Ligi, Marco
Brunelli, Daniele
Cipriani, Anna
Fabretti, Paola
Ferrante, Valentina
Gasperini, Luca
Ottolini, Luisa
Date:
Type:
Articles
Department:
Lamont-Doherty Earth Observatory
Volume:
423
Permanent URL:
Book/Journal Title:
Nature
Abstract:
A 20-Myr record of creation of oceanic lithosphere is exposed along a segment of the central Mid-Atlantic Ridge on an uplifted sliver of lithosphere. The degree of melting of the mantle that is upwelling below the ridge, estimated from the chemistry of the exposed mantle rocks, as well as crustal thickness inferred from gravity measurements, show oscillations of 3–4 Myr superimposed on a longer-term steady increase with time. The time lag between oscillations of mantle melting and crustal thickness indicates that the mantle is upwelling at an average rate of 25 mm yr-1, but this appears to vary through time. Slow-spreading lithosphere seems to form through dynamic pulses of mantle upwelling and melting, leading not only to along-axis segmentation but also to across-axis structural variability. Also, the central Mid-Atlantic Ridge appears to have become steadily hotter over the past 20 Myr, possibly owing to north–south mantle flow.
Subject(s):
Marine geology
Publisher DOI:
http://dx.doi.org/10.1038/nature01594
Item views:
63
Metadata:
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