Continents in the Mantle Transition Zone? Sediment Recycling and the Geochemical Fertilization of the Deep Mantle

由于其固有的组成浮力，传统上认为大陆地壳在密度较大的下地幔中是不可俯冲的。然而，一些海洋岛屿玄武岩在其地幔深处的羽流源中带有循环大陆物质的地球化学特征。这个项目将通过高压实验来解决这个矛盾，高压实验将模拟大陆沉积物俯冲到地幔深处。这些实验将为沉积物衍生流体在地幔交代作用中的作用、富含经济价值的钾质岩浆的起源以及最终到达洋岛玄武岩羽源的超难熔大陆成分的性质提供第一个经验约束。

Because of its intrinsic compositional buoyancy, continental crust has traditionally been considered to be unsubductable in the denser underlying mantle. Yet some ocean island basalts carry a geochemical signature of recycled continental material in their plume source in the deep mantle. This project will reconcile this paradox through high-pressure experiments that will simulate subduction of continental sediments into the deep mantle. These experiments will provide the first empirical constraints on the role of sediment-derived fluids in mantle metasomatism and the origin of economically-rich potassic magmas, and the nature of the ultrarefractory continental component that ultimately reaches the plume source for ocean-island basalts.