Temperature fluctuation of the Iceland mantle plume through time
Temperature fluctuation of the Iceland mantle plume through time
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DOI：
10.1002/2015gc006059
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发表时间：
2016-02
期刊：
影响因子：
3.7
通讯作者：
Holly E. Spice;J. Fitton;L. Kirstein
中科院分区：
文献类型：
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作者：
Holly E. Spice;J. Fitton;L. Kirstein
新开发的橄榄石铝地温计被用来确定跨越北大西洋火成岩省（NAIP）时空范围的一套苦铁矿的橄榄石-铬尖晶石结晶温度，这被广泛认为是深层地幔柱的结果。我们的数据证实，启动羽流与大空间区域上的异常热地幔脉冲有关，然后集中成狭窄的上升流。我们发现，巴芬岛/西格陵兰岛和不列颠群岛两侧直径约 2000 公里的地区，约 61 Ma 的热异常是均匀的，橄榄石中铝的温度比平均洋中脊玄武岩 (MORB) 原始岩浆温度高约 300°C。此外，通过将我们的结果与地球化学数据以及现有的地球物理和测深观测相结合，我们为冰岛地幔柱温度的长期（>107年）波动提供了令人信服的证据。我们发现羽流温度从启动阶段的最初高值降至约 35 Ma 的最低值，并且冰岛下方的地幔温度目前正在上升。
The newly developed Al‐in‐olivine geothermometer was used to find the olivine‐Cr‐spinel crystallization temperatures of a suite of picrites spanning the spatial and temporal extent of the North Atlantic Igneous Province (NAIP), which is widely considered to be the result of a deep‐seated mantle plume. Our data confirm that start‐up plumes are associated with a pulse of anomalously hot mantle over a large spatial area before becoming focused into a narrow upwelling. We find that the thermal anomaly on both sides of the province at Baffin Island/West Greenland and the British Isles at ∼61 Ma across an area ∼2000 km in diameter was uniform, with Al‐in‐olivine temperatures up to ∼300°C above that of average mid‐ocean ridge basalt (MORB) primitive magma. Furthermore, by combining our results with geochemical data and existing geophysical and bathymetric observations, we present compelling evidence for long‐term (>107 year) fluctuations in the temperature of the Iceland mantle plume. We show that the plume temperature fell from its initial high value during the start‐up phase to a minimum at about 35 Ma, and that the mantle temperature beneath Iceland is currently increasing.