Cratonic root beneath North America shifted by basal drag from the convecting mantle
Cratonic root beneath North America shifted by basal drag from the convecting mantle
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DOI：
10.1038/ngeo2525
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发表时间：
2015-10
影响因子：
18.3
通讯作者：
M. Kaban;W. Mooney;A. Petrunin
中科院分区：
文献类型：
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作者：
M. Kaban;W. Mooney;A. Petrunin
稳定的大陆克拉通是地球上最古老的地质特征。它们经历了38到25亿年的地球演化。克拉通得以保存的关键在于其坚固而厚实的岩石圈根，相对于周围的地幔，这些岩石圈根具有中性或正浮力。大多数这些太古宙克拉通根被认为自形成以来一直保持稳定，并且太粘而不受地幔对流的影响，，。在这里，我们结合了重力、地形、地壳结构和地震层析成像数据，表明北美苏必利尔省下方克拉通根的最深处相对于克拉通中心向西南偏西方向移动了约850公里。我们利用数值模拟表明，这种移动可能是由地幔流动引起的基底阻力引起的，这意味着地幔流动可以改变克拉通的结构。我们的观察结果与传统观点相矛盾，传统观点认为克拉通是静态的，非演化的地质特征。我们得出结论，深层大陆根与对流地幔之间可能存在显著的相互作用。
Stable continental cratons are the oldest geologic features on the planet. They have survived 3.8 to 2.5 billion years of Earth’s evolution,. The key to the preservation of cratons lies in their strong and thick lithospheric roots, which are neutrally or positively buoyant with respect to surrounding mantle,. Most of these Archaean-aged cratonic roots are thought to have remained stable since their formation and to be too viscous to be affected by mantle convection,,. Here we use a combination of gravity, topography, crustal structure and seismic tomography data to show that the deepest part of the craton root beneath the North American Superior Province has shifted about 850 km to the west–southwest relative to the centre of the craton. We use numerical model simulations to show that this shift could have been caused by basal drag induced by mantle flow, implying that mantle flow can alter craton structure. Our observations contradict the conventional view of cratons as static, non-evolving geologic features. We conclude that there could be significant interaction between deep continental roots and the convecting mantle.