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首页> 外文期刊>Geochemistry, geophysics, geosystems >Major influence of plume-ridge interaction, lithosphere thickness variations, and global mantle flow on hotspot volcanism-The example of Tristan
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Major influence of plume-ridge interaction, lithosphere thickness variations, and global mantle flow on hotspot volcanism-The example of Tristan

机译：羽-脊相互作用，岩石圈厚度变化和全球地幔流动对热点火山作用的主要影响-以特里斯坦为例

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Hotspot tracks are thought to originate when mantle plumes impinge moving plates. However, many observed cases close to mid-ocean ridges do not form a single age-progressive line, but vary in width, are separated into several volcanic chains, or are distributed over different plates. Here we study plume-ridge interaction at the example of the Tristan plume, which features all of these complexities. Additionally, the South Atlantic formed close to where plume volcanism began, opening from the south and progressing northward with a notable decrease in magmatism across the Florianopolis Fracture Zone. We study the full evolution of the Tristan plume in a series of three-dimensional regional models created with the convection code ASPECT. We then compute crustal thickness maps and compare them to seismic profiles and the topography of the South Atlantic. We find that the separation of volcanism into the Tristan and Gough chain can be explained by the position of the plume relative to the ridge and the influence of the global flow field. Plume material below the off-ridge track can flow toward the ridge and regions of thinner lithosphere, where decompression melting leads to the development of a second volcanic chain resembling the Tristan and Gough hotspot tracks. Agreement with the observations is best for a small plume buoyancy flux of 500 kg/s or a low excess temperature of 150 K. The model explains the distribution of syn-rift magmatism by hot plume material that flows into the rift and increases melt generation.
机译：热点轨迹被认为是地幔柱撞击移动板块的起点。但是，许多观察到的靠近海洋中脊的案例并未形成单一的年龄渐进线，而是宽度不同，被分成几条火山链或分布在不同的板块上。在这里，我们以特里斯坦羽状流为例研究羽状-岭状相互作用，它具有所有这些复杂性。此外，南大西洋形成于靠近火山爆发的地方，从南部开始向北发展，整个弗洛里亚诺波利斯断裂带的岩浆活动明显减少。我们在用对流代码ASPECT创建的一系列三维区域模型中研究Tristan羽的完整演化。然后，我们计算地壳厚度图，并将其与地震剖面和南大西洋的地形进行比较。我们发现，火山作用分离为Tristan和Gough链条可以通过羽相对于山脊的位置以及全球流场的影响来解释。脊外轨道下方的羽状物质可以流向脊和较薄岩石圈的区域，在那里减压融化导致形成类似于Tristan和Gough热点轨道的第二条火山链。对于较小的羽流浮力为500 kg / s或较低的过高温度为150 K，与观测值一致是最佳的。该模型解释了流入裂谷并增加熔体生成的热羽状物质对同裂谷岩浆的分布。

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