Western US volcanism due to intruding oceanic mantle driven by ancient Farallon slabs
Western US volcanism due to intruding oceanic mantle driven by ancient Farallon slabs
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DOI：
10.1038/s41561-017-0035-y
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发表时间：
2018-04
影响因子：
18.3
通讯作者：
Quan Zhou;Lijun Liu;Jiashun Hu
中科院分区：
文献类型：
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作者：
Quan Zhou;Lijun Liu;Jiashun Hu
美国西部晚新生代板内火山作用的起源是有争议的。一个重要的原因是缺乏对这一火山历史中地幔动力学的清晰理解。在这里，我们重建地幔热状态下北美自2000万年前使用混合逆地球动力学模型与数据同化。该模型同时满足过去俯冲运动学、现今地幔层析成像和火山活动历史。我们发现，在黄石火山省和盆地和山脉省的火山活动对应于一个类似的向东侵入地幔来自太平洋下方，主要是由下沉的Farallon板低于美国中东部。形成哥伦比亚河泛滥玄武岩和随后的黄石-纽贝里热点轨迹的热地幔首先通过胡安·德富卡板块内的裂缝进入美国西部。随后，向西的软流层流以上的撤退胡安德富卡板和向东传播的地幔超出弧后地区的共存再现分叉热点链。一个类似的，但较弱的热源侵入盆地和山脉的南部边缘周围的板，并可以解释在这个地区的扩散玄武质火山作用。根据我们的模型，假定的黄石火山柱对黄石火山区的形成贡献不大。
The origin of late Cenozoic intraplate volcanism over the western United States is debated. One important reason is the lack of a clear understanding of the mantle dynamics during this volcanic history. Here we reconstruct the mantle thermal states beneath North America since 20 million years ago using a hybrid inverse geodynamic model with data assimilation. The model simultaneously satisfies the past subduction kinematics, present mantle tomographic image and the volcanic history. We find that volcanism in both the Yellowstone volcanic province and the Basin and Range province corresponds to a similar eastward-intruding mantle derived from beneath the Pacific Ocean and driven mostly by the sinking Farallon slab below the central-eastern United States. The hot mantle that forms the Columbia River flood basalt and subsequent Yellowstone–Newberry hotspot tracks first enters the western United States through tears within the Juan de Fuca slab. Subsequent coexistence of the westward asthenospheric flow above the retreating Juan de Fuca slab and eastward-propagating mantle beyond the back-arc region reproduces the bifurcating hotspot chains. A similar but weaker heat source intrudes below the Basin and Range around the southern edge of the slab, and can explain the diffuse basaltic volcanism in this region. According to our models, the putative Yellowstone plume contributes little to the formation of the Yellowstone volcanic province.