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

由于其固有的成分浮力，大陆地壳传统上被认为在密度更高的下地幔中是不可俯冲的。然而，一些大洋岛玄武岩在其地幔深处的羽流来源中带有回收大陆物质的地球化学特征。该项目将通过模拟大陆沉积物向地幔深处俯冲的高压实验来调和这一悖论。这些实验将首次对沉积流体在地幔交代中的作用、经济丰富的钾质岩浆的起源以及最终到达洋岛玄武岩羽流来源的超难熔大陆成分的性质提供经验约束。

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.