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

被引:104
作者
Bonatti, E
Ligi, M
Brunelli, D
Cipriani, A
Fabretti, P
Ferrante, V
Gasperini, L
Ottolini, L
机构
[1] CNR, Ist Sci Marine, I-40129 Bologna, Italy
[2] Univ Roma La Sapienza, Dipartimento Sci Terra, I-00187 Rome, Italy
[3] Columbia Univ, Lamont Doherty Earth Observ, Dept Earth & Environm Sci, Palisades, NY 10964 USA
[4] CNR, Ist Geosci & Georisorse, Sez Pavia, I-27100 Pavia, Italy
基金
美国国家科学基金会;
关键词
D O I
10.1038/nature01594
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
A 20-Myr record of creation of oceanic lithosphere at a segment of the central Mid-Atlantic-Ridge is exposed along 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 similar to3-4 Myr superimposed on a longer-term steady increase with time. The time lag between oscillations of mantle melting and crustal thickness indicates that the solid mantle is upwelling at an average rate of similar to25 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.
引用
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页码:499 / 505
页数:7
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