Rheological controls on slab delamination

俯冲洋岩石圈表现出一系列复杂的行为，包括侵入下地幔，在过渡带停滞，在660 km地震不连续处或恰好在660 km地震不连续处沉积，以及这些端元之间的中间行为。在更精细的尺度上，MORB组分被认为与板状岩心机械分离，在下地幔中产生地震散射体，并在核幔边界和过渡带底部形成富含OIB物质的潜在储层。板块及其不同组成部分的确切行为将取决于它们相对于彼此和周围地幔的密度和强度。虽然地幔中各种岩石和矿物的密度是众所周知的，但我们对它们的强度所知甚少；地球动力学模拟显示了一系列依赖于这些属性的板的行为。我们将测量构成板块的主要岩石（洋中脊玄武岩和贫化橄榄岩）在俯冲板块至~1000 km深度的压力和温度条件下的相对强度。这将使我们能够评估沿板块地热的两种成分的哪个相组合显示了主要的流变对比，从而更好地理解板块变形和分层的过程。

Subducted oceanic lithosphere displays a range of complex behaviours including penetration into the lower mantle, stagnation in the transition zone and ponding at, or just below, the 660 km seismic discontinuity, and intermediate behaviour between these end-members. At a finer scale, the MORB component is thought to mechanically decouple from the slab core to produce seismic scatterers in the lower mantle and potential reservoirs for enriched OIB material at the core-mantle boundary and the base of the transition zone. The exact behaviour of the slab and its different components will depend on their densities and strengths relative to each other and the surrounding mantle. While the densities of the various rocks and minerals in the mantle are well known our knowledge of their strengths is very poor; geodynamical simulations show a range of slab behaviours dependent on these properties. We will measure the relative strength of the main rocks which comprise the slab (mid-ocean-ridge basalt and depleted peridotite) under the range of pressure and temperature conditions of the subducting slab to ~1000 km depth. This will allow us to assess which phase assemblages of the two compositions along the slab geotherm show the main rheological contrasts and hence better understand the processes of slab deformation and delamination.