Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variations in the formation of oceanic lithosphere
Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variations in the formation of oceanic lithosphere
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DOI：
10.1038/nature01594
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发表时间：
2003-05-29
期刊：
影响因子：
64.8
通讯作者：
Ottolini, L
中科院分区：
文献类型：
--
作者：
Bonatti, E;Ligi, M;Ottolini, L
一个20万年前的海洋岩石圈的创建记录，在中央大西洋中脊的一段暴露沿着上升的岩石圈的一条。从暴露的地幔岩石的化学成分估计的海岭下上涌地幔的熔融程度，以及从重力测量推断的地壳厚度，显示出类似于3 -4百万年的振荡叠加在一个长期稳定的增加随时间。地幔熔融和地壳厚度的振荡之间的时间滞后表明，固体地幔上涌的平均速率约为25毫米/年，但这似乎随时间而变化。缓慢扩张的岩石圈似乎是通过地幔上涌和熔融的动态脉冲形成的，不仅导致沿轴向的分段，而且导致轴向的结构变化。此外，在过去的2000万年里，大西洋中脊中部似乎变得越来越热，这可能是由于南北地幔流动。
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.