High mantle temperatures following rifting caused by continental insulation
High mantle temperatures following rifting caused by continental insulation
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DOI：
10.1038/ngeo1758
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发表时间：
2013-05-01
影响因子：
18.3
通讯作者：
Haase, Karsten M.
中科院分区：
文献类型：
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作者：
Brandl, Philipp A.;Regelous, Marcel;Haase, Karsten M.
大陆的分布被认为会影响下面地幔的温度。在地质时间尺度上，隔热效应产生热量积聚，可能导致岩浆活动增加（1-4），如洪水玄武岩火山活动（5，6），并最终使大陆断裂，导致它们分裂，形成新的海洋盆地。在这里，我们使用的主要元素地球化学分析的熔岩样本收集的大洋地壳在大西洋和太平洋的量化大陆绝缘的影响。熔岩形成于大洋中脊，伴随着大陆裂谷和断裂，并保存了过去1.7亿年的上地幔温度记录。我们发现，来自太平洋的样本-距离最近的大陆边缘超过2,000公里-没有记录地幔温度升高。相比之下，在大陆边缘附近形成的大西洋样本显示，大陆裂谷后的上地幔温度比现在的平均温度高出150摄氏度;地幔温度保持在6000万至7000万年的高位。我们的结论是，大西洋的热异常是由大陆绝缘，并坚持在地幔下的大西洋大陆碎片分散后很久。
The distribution of continents is thought to influence the temperature of the underlying mantle. Over geological timescales, insulation effects generate a build-up of heat that may cause increased magmatism(1-4), such as flood basalt volcanism(5,6), and ultimately rift the continents, causing them to break apart and new ocean basins to form. Here we use analyses of the major element geochemistry of lava samples collected from oceanic crust in the Atlantic and Pacific oceans to quantify the effect of continental insulation. The lavas formed at mid-ocean ridges following continental rifting and break up, and preserve a record of upper mantle temperatures over the past 170 Myr. We find that samples from the Pacific Ocean-formed more than 2,000 km from the nearest continental margin-do not record raised mantle temperatures. In contrast, samples from the Atlantic Ocean that formed close to the margin of the rifted continent reveal an upper mantle temperature immediately after continental rifting that was up to 150 degrees C higher than the present-day average; mantle temperatures remained high for 60-70 Myr. We conclude that the Atlantic thermal anomaly was created by continental insulation, and persisted in the mantle beneath the Atlantic Ocean long after the continental fragments had dispersed.