African cratonic lithosphere carved by mantle plumes
African cratonic lithosphere carved by mantle plumes
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DOI：
10.1038/s41467-019-13871-2
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发表时间：
2020-01-03
影响因子：
16.6
通讯作者：
Gaina, Carmen
中科院分区：
文献类型：
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作者：
Celli, Nicolas Luca;Lebedev, Sergei;Gaina, Carmen
克拉通是大陆的古老核心，自2.5Ga前形成以来，它们是如何演化的，人们对此存在争议。地震层析成像可以绘制厚厚的克拉通岩石圈的地图，但在采样稀少的大陆上，其分辨率较低。在这里，我们使用波形层析成像和新获得的大型数据集显示，非洲克拉通岩石圈比以前看到的更加复杂和支离破碎。大多数已知的含钻石的金伯利岩，表明喷发时岩石圈很厚，是今天岩石圈很薄的地方，这意味着在过去200 Ma，岩石圈的侵蚀令人惊讶地广泛。在岩石圈丧失的同时或之前，被归因于深部地幔热柱的大型火成岩省被部署在所有岩石圈丧失地点附近。这表明，克拉通根部一旦被地幔热柱改造就会下沉。我们的结果表明，自太古宙形成以来，克拉通岩石圈的总体积已经减少，每个克拉通的命运取决于它相对于羽流的运动。
How cratons, the ancient cores of continents, evolved since their formation over 2.5 Ga ago is debated. Seismic tomography can map the thick lithosphere of cratons, but its resolution is low in sparsely sampled continents. Here we show, using waveform tomography with a large, newly available dataset, that cratonic lithosphere beneath Africa is more complex and fragmented than seen previously. Most known diamondiferous kimberlites, indicative of thick lithosphere at the time of eruption, are where the lithosphere is thin today, implying surprisingly widespread lithospheric erosion over the last 200 Ma. Large igneous provinces, attributed to deep-mantle plumes, were emplaced near all lithosphere-loss locations, concurrently with or preceding the loss. This suggests that the cratonic roots foundered once modified by mantle plumes. Our results imply that the total volume of cratonic lithosphere has decreased since its Archean formation, with the fate of each craton depending on its movements relative to plumes.